Crocodile Lake National Wildlife Refuge Comprehensive Conservation Plan

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Comprehensive Conservation Plan
Crocodile Lake Wildlife Refuge
Crocodile Lake National Wildlife Refuge
P.O. Box 370
Key Largo, FL 33037
Telephone(305) 451-4223
FAX: (305) 451-1508
E-mail: crocodilelake@fws.gov
Website: http://southeast.fws.gov/CrocodileLake
U.S. Fish & Wildlife Service
1 800/344 WILD
http://www.fws.gov
U.S. Fish & Wildlife Service
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Comprehensive Conservation Plan
Crocodile Lake
National Wildlife Refuge
Crocodile
Photo provided by
bigfoto.com
Crocodile Lake National Wildlife Refuge
Comprehensive Conservation Plan
U.S. Department of the Interior
Fish and Wildlife Service
Southeast Region
February 2006
CROCODILE LAKE NATIONAL WILDLIFE REFUGE
COMPREHENSIVE CONSERVATION PLAN
U.S. Department of the Interior
Fish and Wildlife Service
Southeast Region
1875 Century Boulevard
Atlanta, Georgia 30345
February 2006
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TABLE OF CONTENTS
SECTION A. COMPREHENSIVE CONSERVATION PLAN
I. BACKGROUND .................................................................................................................................1
Introduction..................................................................................................................................1
Purpose and Need for Plan ..........................................................................................................2
U.S. Fish and Wildlife Service ......................................................................................................2
National Wildlife Refuge System ..................................................................................................3
Legal Policy Context.....................................................................................................................3
Relationship to State Partners......................................................................................................4
Ecosystem Context.......................................................................................................................5
Ecological Threats and Problems.................................................................................................5
Exotics................................................................................................................................5
Public Use ...........................................................................................................................5
Wetland Protection..............................................................................................................6
Water Quality ......................................................................................................................6
Contaminants ......................................................................................................................6
Habitat Loss ........................................................................................................................6
Coastal Impacts ..................................................................................................................6
Lack of Knowledge..............................................................................................................7
Air Quality...........................................................................................................................7
Land Use............................................................................................................................7
Law Enforcement ................................................................................................................7
Conservation Priorities .................................................................................................................7
II. REFUGE DESCRIPTION...................................................................................................................9
Introduction..................................................................................................................................9
Refuge Location ...........................................................................................................................9
Refuge Purposes.........................................................................................................................9
Role of Crocodile Lake National Wildlife Refuge........................................................................11
Refuge Environment...................................................................................................................11
Fish and Wildlife Populations, Including Federally Listed Species ...................................11
Topography......................................................................................................................12
Geology............................................................................................................................12
Soils .................................................................................................................................12
Minerals............................................................................................................................12
Hydrology ..........................................................................................................................12
Air and Water Quality ........................................................................................................13
Habitats .............................................................................................................................13
Invasive Species ...............................................................................................................16
Cultural Resources............................................................................................................16
Partnerships and Coordination ...................................................................................................17
Recreational and Commercial Use on the Refuge .....................................................................17
Current Management Practices..................................................................................................17
Facilities and Structures .............................................................................................................18
Wilderness Review .....................................................................................................................19
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III. PLAN DEVELOPMENT ..................................................................................................................21
Public Involvement and the Planning Process ...........................................................................21
Issues and Concerns .................................................................................................................21
Wildlife and Habitat Conservation.....................................................................................22
Land Protection and Conservation ...................................................................................22
Education and Visitor Services .........................................................................................22
Refuge Administration ......................................................................................................22
IV. MANAGEMENT DIRECTION.........................................................................................................23
Introduction ...............................................................................................................................23
Vision ........................................................................................................................................23
Management Plan Summary......................................................................................................23
Goals, Objectives, and Strategies..............................................................................................24
Goal 1 ...............................................................................................................................24
Goal 2 ...............................................................................................................................34
Goal 3 ...............................................................................................................................36
V. PLAN IMPLEMENTATION.............................................................................................................37
Introduction ...............................................................................................................................37
Proposed Projects......................................................................................................................37
Project 1: Invasive Exotic Plant Control ...........................................................................37
Project 2: Invasive Exotic Pest Control ............................................................................37
Project 3: Feral And Free-Roaming Cat Control ..............................................................37
Project 4: Crocodile Nesting Berm Replenishment..........................................................38
Project 5: Habitat Restoration..........................................................................................38
Project 6: Woodrat Artificial Nest Sites ............................................................................38
Project 7: Schaus Swallowtail Butterfly Plants.................................................................38
Project 8: Monitoring and Population Surveys .................................................................38
Project 9: Land Acquisition ..............................................................................................38
Project 10: Volunteer program.........................................................................................39
Project 11: Butterfly Garden and Interpretive Materials ...................................................39
Staffing Needs...........................................................................................................................40
Step-Down Plans........................................................................................................................40
Partnership Opportunities ..........................................................................................................40
Monitoring and Adaptive Management.......................................................................................40
VI. CONSULTATION AND COORDINATION......................................................................................43
Introduction ...............................................................................................................................43
Core Planning Team.........................................................................................................43
Biological Review Team....................................................................................................43
SECTION B. APPENDICES
I. GLOSSARY....................................................................................................................................45
II. REFERENCES ...............................................................................................................................51
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III. RELEVANT LEGAL MANDATES....................................................................................................53
National Wildlife Refuge System Authorities ..............................................................................53
Key Legislation/Policies for Plan Implementation.......................................................................53
IV. PUBLIC INVOLVEMENT................................................................................................................59
Public Scoping...........................................................................................................................59
V. COMPATIBILITY DETERMINATIONS ............................................................................................61
Introduction................................................................................................................................61
VI. SECTION 7 INTRA-SERVICE CONSULTATION...........................................................................65
VII. REFUGE BIOTA...........................................................................................................................71
VIII. LIST OF PREPARERS...............................................................................................................115
IX. SUMMARY OF PUBLIC COMMENTS AND THE SERVICE’S RESPONSES ............................117
X. FINDING OF NO SIGNIFICANT IMPACT ....................................................................................121
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LIST OF FIGURES
Figure 1. Crocodile Lake National Wildlife Refuge location................................................................10
Figure 2. Crocodile Lake National Wildlife Refuge habitat .................................................................14
Coordinate research with proposed habitat management programs and activities to
determine impacts on threatened and endangered species................................................34
Figure 3. Crocodile Lake National Wildlife Refuge land ownership....................................................35
LIST OF TABLES
Table 1. Cost summary of projects .....................................................................................................39
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SECTION A. COMPREHENSIVE CONSERVATION PLAN
I. Background
INTRODUCTION
Crocodile Lake National Wildlife Refuge, operating as a satellite of the National Key Deer Refuge, is
on upper Key Largo in Monroe County, Florida. The refuge was established in April 1980 under the
authorities of the Endangered Species Act of 1973 (as amended), and the Land and Water
Conservation Fund Act of 1965 (as amended in 1976). It currently covers 6,700 acres, including 650
acres of open water. It contains a mosaic of habitat types, including tropical hardwood hammock,
mangrove forest, and salt marsh. These habitats are vital for hundreds of plants and animals,
including six federally listed species.
Crocodile Lake Refuge is unusual in that not all of the critical habitat areas are in a pristine,
undisturbed condition. A large portion of the refuge was slated to become a residential development,
complete with canals for boating access. The organic peat dredge-spoil from the canal system was
piled up in berms on the banks of the canals and became an important nesting area for the federally
listed American crocodile. Crocodiles are fairly wide-spread throughout the tropics with American
crocodiles somewhat widely distributed in the American tropics. In the United States, crocodiles are
only found in south Florida and the Keys.
The refuge protects one of the largest remaining tracts of tropical hardwood hammock, which is a
globally threatened habitat type. These diverse forests are home to hundreds of plants and animals,
including the federally listed Key Largo woodrat, Key Largo cotton mouse, Schaus swallowtail
butterfly, Stock Island tree snail, and eastern indigo snake. These species require hammocks in
order to survive. Unfortunately, most of the hammocks in Key Largo have been eliminated by
development, which has lead to considerable population declines in these already imperiled species.
Management initiatives on the refuge include exotic plant removal and habitat protection. The refuge
is closed to public access to protect critical habitat. A casual visitor might think that Key Largo is little
more than a highly developed, tourist-oriented island. However, much of north Key Largo has been
set aside as a natural area for the protection of threatened and endangered species and their
habitats. Acre-for-acre, few places on earth harbor more threatened and endangered plants and
animals than Crocodile Lake Refuge and the adjacent Dagny Johnson Key Largo Hammock
Botanical State Park.
The mix of pristine natural areas and disturbed areas on the refuge creates many management
challenges. Natural areas are important to a multitude of species, as are the disturbed areas.
Typically, habitat management strives to restore disturbed habitats to a pre-disturbance state. At the
refuge, federally listed species, such as the American crocodile and the Key Largo woodrat, thrive in
disturbed areas. Thus, management of the refuge must undertake actions that seem contradictory to
the maintenance of ecological integrity.
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PURPOSE AND NEED FOR PLAN
The National Wildlife Refuge System Improvement Act of 1997 established a clear legislative mission
of wildlife conservation for the National Wildlife Refuge System. Activities were initiated in 1997 to
complement the direction of this new legislation, including an effort to complete 15-year management
plans (i.e., comprehensive conservation plans) for all refuges. These plans, which are conducted
with full public involvement, help guide the management of refuges, including providing management
direction for natural resources, as well as recreation and education programs.
The Act states that each refuge shall be managed to:
• Fulfill the mission of the Refuge System;
• Fulfill the individual purposes of each refuge;
• Consider the needs of fish and wildlife first;
• Fulfill the requirement of developing a comprehensive conservation plan for each unit of the
Refuge System and fully involve the public in the preparation of these plans;
• Maintain the biological integrity, diversity, and environmental health, cumulatively referred to
as “ecological integrity” of the Refuge System; and
• Recognize that wildlife-dependent recreation activities, including hunting, fishing, wildlife
observation, wildlife photography, and environmental education and interpretation, are
legitimate and priority public uses of national wildlife refuges.
The purpose of this plan is to identify the role the refuge will play in support of the mission of the
National Wildlife Refuge System, and to provide guidance for managing the refuge through the next
15 years. This plan is designed to fulfill the following:
• Provide a clear statement of the desired future condition of the refuge;
• Provide refuge neighbors, visitors, and partners with a clear understanding of the reasons for
management actions on and around the refuge;
• Ensure that management of the refuge is consistent with mandates of the National Wildlife
Refuge System;
• Ensure that refuge management is consistent with other federal, state, and county plans;
• Provide long-term guidance and continuity for refuge management; and
• Provide a basis for operation, maintenance, and capital improvement budget requests.
U.S. FISH AND WILDLIFE SERVICE
The U.S. Fish and Wildlife Service is the primary federal agency responsible for the conservation,
protection, and enhancement of the Nation’s fish and wildlife populations and habitats. Although the
Service shares some conservation responsibilities with other federal, state, tribal, local, and private
entities, it has specific trustee obligations for migratory birds, threatened and endangered species,
anadromous fish, and certain marine mammals.
The mission of the Service is:
“Working with others, to conserve, protect, and enhance fish, wildlife, and plants and
their habitats for the continuing benefit of the American people.”
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NATIONAL WILDLIFE REFUGE SYSTEM
As part of its mission, the Service administers the National Wildlife Refuge System, a national
network of lands and waters for the management and protection of these resources. To date, the
Refuge System encompasses more than 540 national wildlife refuges and more than 3,000 small
waterfowl breeding and nesting sites that protect upwards of 95 million acres. This is the world=s
largest collection of lands and waters specifically managed for conservation of fish and wildlife. The
majority of these lands, 77 million acres, are in Alaska. The remaining acres are spread across the
other 49 states and several island U.S. territories.
The mission of the Refuge System is:
“To administer a national network of lands and waters for the conservation,
management, and where appropriate, restoration of the fish, wildlife and plant
resources and their habitats within the United States for the benefit of present and
future generations of Americans.”
--National Wildlife Refuge System Improvement Act of 1997
The wildlife and habitat vision for national wildlife refuges stresses that wildlife come first; that
ecosystems, biodiversity, and wilderness are vital concepts in refuge management; that the
ecological integrity of refuges is maintained; that the growth of refuges and the Refuge System must
be strategic; and that the Refuge System serves as a model for habitat management with broad
participation from others. This broad participation includes local, state, and federal government
partners; organizations; the local business communities; individuals; and volunteers. Volunteers
continue to be a major contributor to the success of the Refuge System and in 2004, 6,349 volunteers
supported 125 stations and contributed 293,937 hours with a value of more than five million dollars in
the Southeast Region.
The National Wildlife Refuge System hosts more than 35 million annual visitors. Economists found
that these refuge visitors contribute more than $400 million annually to local economies. In 2001, on
conservation lands throughout the nation, approximately 37.8 million people participated in wildlife-related
activities, most to observe wildlife in their natural habitats. These visitors represent nearly 40
percent of the country’s adults who spent $108 billion on wildlife-related pursuits in 2001, according to
the National Survey of Fishing, Hunting, and Wildlife-Associated Recreation (U.S. Department of
Interior, Fish and Wildlife Service and U.S. Department of Commerce, U.S. Census Bureau 2002).
As visitation continues to grow on conservation lands and waters in general, and specifically on
refuges, adjacent local communities are realizing significant economic benefits.
LEGAL POLICY CONTEXT
Administration of national wildlife refuges is guided by the mission and goals of the National Wildlife
Refuge System, Congressional legislation, Presidential executive orders, and international treaties.
Policies for management options of refuges are further refined by administrative guidelines
established by the Secretary of the Interior and by policy guidelines established by the Director of the
Fish and Wildlife Service. Management options are guided by a refuge’s establishing authorities;
Public Law 104, Stat. 2957 ('108, H.R. 3338); and the National Wildlife Refuge System Improvement
Act of 1997. (See Appendix III for more information on legal and policy guidance for the operation of
national wildlife refuges.)
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Key guidance and direction can be found in:
• National Wildlife Refuge System Administration Act of 1966;
• Refuge Recreation Act of 1962;
• Title 50 of the Code of Federal Regulations;
• U.S. Fish and Wildlife Service Manual; and
• National Wildlife Refuge System Improvement Act of 1997.
Since refuges must be managed for wildlife first, the lands and waters within the National Wildlife Refuge
System are closed to public uses unless specifically and legally opened under specified conditions allowing
compatibility with the purposes of the refuges. All programs and uses of a refuge must be evaluated based on
mandates set forth in the National Wildlife Refuge System Improvement Act, including to:
• contribute to ecosystem goals, as well as to refuge purpose(s) and goals;
• conserve, manage, and restore fish, wildlife, and plant resources and their habitats;
• monitor the trends of fish, wildlife, and plants;
• maintain ecological integrity;
• manage and ensure compatible wildlife-dependent visitor uses as those uses which benefit
the conservation of fish and wildlife resources and which contribute to the enjoyment of the
public (these uses include hunting, fishing, wildlife observation, wildlife photography, and
environmental education and interpretation); and
• ensure that visitor activities are compatible with refuge purpose(s).
RELATIONSHIP TO STATE PARTNERS
The Fish and Wildlife Service is committed to encouraging and maintaining partnerships with others to
improve the environmental health of ecosystems and the National Wildlife Refuge System. Partnerships
are recognized by the Service as vital to fulfill its mission and help share advocacy for fish and wildlife
resources. Some current partners include other federal agencies, state and local government agencies,
environmental organizations, outdoor sporting groups, industry, and private landowners.
A provision of the National Wildlife Refuge System Improvement Act of 1997 and subsequent agency
policy provide that the Service shall ensure timely and effective cooperation and collaboration with other
federal agencies and state fish and wildlife agencies during the course of acquiring and managing
refuges. For Crocodile Lake Refuge, state fish and wildlife management is administered by the Florida
Fish and Wildlife Conservation Commission (http://www.myfwc.com/) and the Florida Department of
Environmental Protection (http://www.dep.state.fl.us/). These state agencies are charged with
enforcement responsibilities relating to migratory birds, trust species, and fisheries, as well as with
management of natural resources of the state. Both the Florida Fish and Wildlife Conservation
Commission and the Florida Department of Environmental Protection manage state lands and waters.
The Florida Fish and Wildlife Conservation Commission manages 4.3 million acres of public lands and
220,000 acres of private lands for recreation and conservation purposes. The Florida Department of
Environmental Protection manages 150 state parks covering nearly 600,000 acres and 57 coastal and
aquatic managed areas, totaling over 5 million acres of submerged lands and coastal uplands.
Various agencies within the state have also participated in a mix of refuge projects, including the planning
process to develop this 15-year management plan for the refuge. The state’s participation and
contribution throughout this comprehensive conservation planning process has provided for ongoing
opportunities and open dialogue to improve the ecological conservation of fish and wildlife in Florida. An
integral part of the planning process was to integrate common mission objectives, where appropriate.
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ECOSYSTEM CONTEXT
Comprising one of the 52 ecosystems around the country, the Fish and Wildlife Service’s South
Florida Ecosystem encompasses more than 26,000 square miles, 19 southern Florida counties,
and more than 7 million people. The South Florida Ecosystem has undergone numerous human
disturbances, such as alteration of hydro-period, fire history, and drainage patterns. Developing
and dredging the Everglades canal system and expanding agricultural operations have eliminated
and diminished natural systems. Exotic species, such as Australian pine, Brazilian pepper, and
lead tree, are further contributing to wildlife population and habitat declines. Over the last 50
years, the South Florida Ecosystem has undergone dramatic changes, which are largely
attributed to various human activities and economic growth.
Despite the ongoing landscape alteration and rapidly growing economy, the scrub, hardwood
hammocks, cypress swamps, salt marshes, mangrove islands, coral reefs, and seagrass beds of
south Florida support one of the most ecologically diverse systems on the planet. The majority of the
remaining wildlife and habitats of the South Florida Ecosystem is found on national interest lands,
including sixteen national wildlife refuges, three national parks, one national preserve, and one
national marine sanctuary. Despite tremendous economic development, the South Florida
Ecosystem supports more than 600 rare or imperiled species, where 68 are federally listed as
threatened or endangered, including 8 mammals, 13 birds, 10 reptiles, 2 invertebrates, and 35 plants.
ECOLOGICAL THREATS AND PROBLEMS
The following items were identified by the South Florida Ecosystem Team and published in the
team’s plan in 1998. Not all of these threats and problems affect Crocodile Lake Refuge, however,
these issues affect the South Florida Ecosystem, as a whole, and are included here as a frame of
reference. The following threat topics are taken directly from the 1999 South Florida Ecosystem
Team’s Ecosystem Plan section on Florida Keys issues and do not necessarily all apply to the refuge.
EXOTICS
Species of concern include Brazilian pepper, Old-world climbing fern, Australian pine, Asiatic colubrina, lead
tree, knickerbean, and non-native grasses. In both Great White Heron and Key West Refuges, much of the
affected area is on offshore islands where treatment is difficult. Much of the exotic vegetation on the highway
connecting the Keys lies on private property, which makes treatment problematic. Past survey efforts
concluded that roughly 500 acres of Crocodile Lake Refuge, National Key Deer Refuge, Great White Heron
Refuge, and Key West Refuge lands were infested with exotic vegetation. Feral cats are the primary predators
of the endangered Lower Keys marsh rabbit and may be impacting the Key Largo woodrat and cotton mouse.
Imported fire ants attack young sea turtles and endangered endemic rodents. Black rats may eat the young of
endangered rodents and out-compete them for habitat.
PUBLIC USE
The public use carrying capacity of specific areas needs to be addressed. The high level of public
use throughout all of the Keys (e.g., uplands, Florida Bay, reef tract) is the source of many other
critical issues. Many problems are associated with illegal uses and commercial use, particularly in
the lower backcountry islands. Beach use causes disturbance to shorebirds and damages their
loafing and feeding areas. Personal watercraft use, recreational fishing, parasailing, diving, and
snorkeling continue to be increasing problems. Crocodile Lake Refuge has always been a closed
refuge and does not have problems with illegal public uses. The public uses mentioned above are
primarily of concern elsewhere in the Keys.
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WETLAND PROTECTION
There has been substantial restoration of wetlands, such as the Harrison Tract on Crocodile Lake
Refuge and Port Pine Heights Mitigation Project on National Key Deer Refuge. The potential for
these areas to be hydrologically flushed needs to be restored. Freshwater areas are critical for
mammal species. Saltwater wetlands are important nursery areas for reef fish and feeding and
roosting areas for wading birds. Although restoration of some areas is underway, much more is
needed, such as filling of mosquito ditches and unused canals. Water wells associated with
residential development are lowering the freshwater lens on Big Pine Key, making this water
unavailable to wildlife and subject to saltwater intrusion.
WATER QUALITY
This area is affected by nearshore water quality issues of Florida Bay and the Keys reef tract.
Alterations of historic water flow through this sub-region create water quality problems ranging from
loss of seagrass in Florida Bay to coral die-off in the sensitive reef tract. Hydrologic flushing of this
area needs to be restored. Nearshore water quality is impacted by nutrient loading from upstream
and local sources. Sewage treatment plants, septic tanks, cesspits, and live-aboard vessels
represent the most common and widespread sources of pollution and water quality degradation in the
Florida Keys. Boaters in shallow waters and divers stir up the sediments.
CONTAMINANTS
Mosquito spraying is not allowed on Crocodile Lake Refuge but it may be harming invertebrate
populations in North Key Largo, such as the endangered Schaus swallowtail butterfly and Stock
Island tree snail. Possible water table contamination from a landfill inholding at Crocodile Lake
Refuge may be a problem. Lead from firearm ranges is also a known contaminant.
HABITAT LOSS
The primary threats to upland habitats in the Florida Keys are economic development, fragmentation
by infrastructure, and invasion of exotic vegetation. Wetland restoration is helping to reverse existing
habitat loss. At Crocodile Lake Refuge, loss of adjacent tropical hardwood hammock habitat for
residential purposes is the largest problem. Losses of seagrass in Florida Bay and coral die-off in the
reef tract are also problems associated with commercial and public uses.
COASTAL IMPACTS
Some natural erosion has been exacerbated by human use and boat wakes, particularly on
backcountry islands. Sea level rise could eventually affect wetlands and mangrove forests by
altering tidal and hydrologic cycles.
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LACK OF KNOWLEDGE
More information is needed on the public use carrying capacity for the Florida Keys, particularly for commercial
use. Information is also needed on the extent of exotic plant invasions and the role of fire in pine rocklands in
the lower Keys. Baseline data for water quality and faunal and floral inventories are also needed.
AIR QUALITY
This is not believed to be an issue as there are no major industries.
LAND USE
The primary problem is increased human population growth, with its subsequent residential and
associated commercial development and landfill activities. In the backcountry waters and coral reef
communities, a primary problem is increased competition for support and space between species,
including humans, and the resulting damage and problems.
LAW ENFORCEMENT
The full scope of law enforcement activities should be performed to eliminate the unlawful take of
migratory birds, threatened and endangered species, and other native wildlife and plants. Traffic
enforcement and prevention of illegal feeding of Key deer are critical to the survival of this species.
CONSERVATION PRIORITIES
The South Florida Ecosystem Team’s plan identified seven goals. Each goal was established by
ecosystem team members to accomplish the tasks identified by the Interagency Task Force. The
goals recognize refuges and other national interest lands as cornerstones of an ecosystem approach
to resource conservation and management. Refuge land managers will consider landscapes beyond
their respective boundaries and focus on the overall environmental health and biological integrity of
the ecosystem. The conservation priorities for the South Florida Ecosystem are reflected in the
following seven goals:
1. Protect and manage units of the National Wildlife Refuge System and other national
interest lands.
2. Protect migratory birds and protect, restore, and manage their habitats.
3. Protect, restore, and manage candidate, threatened, and endangered species and their
habitats.
4. Protect, restore, and manage wetlands and other freshwater habitats.
5. Protect, manage, and restore fish and other aquatic species and their habitats.
6. Protect, restore, and enhance coastal and estuarine habitats.
7. Protect, restore, and manage for biodiversity.
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II. Refuge Description
INTRODUCTION
The refuge was established in April 1980 to protect and preserve critical habitat for the American
crocodile. The refuge is also home to five other indigenous species listed as federally threatened and
endangered. The refuge and surrounding waters are habitat for more than 80 other wildlife and plant
species that are listed by federal, state, or county agencies as threatened, endangered, candidate, or
otherwise protected. The refuge was established under the authorities of the Land and Water
Conservation Fund Act of 1965, as amended in 1976 (Public Law 94-422), and the Endangered
Species Act of 1973 (Public Law 93-295, 87 Stat. 884), as amended.
The refuge was established with an initial purchase of 85 acres at a cost of $41,250. Subsequent
land purchases did not begin again until February 1981, at which time purchases proceeded at a
steady pace until 1994 and resulted in an additional 6,475 acres being acquired. Also in 1994, the
Service entered into a 99-year lease agreement with the State of Florida for approximately 125 acres
that exist within the refuge acquisition boundaries. The last purchases, encompassing almost 2
acres, occurred in 1998, placing the total lands under refuge control at 6,688 acres.
The refuge serves as a satellite refuge of National Key Deer Refuge and was not staffed until 1997,
when a refuge manager was hired for the refuge. Over the years, refuge administration and
management have been supplemented by staff from National Key Deer Refuge, as well as interns,
university researchers, and volunteers.
REFUGE LOCATION
Crocodile Lake National Wildlife Refuge is on North Key Largo in Monroe County, Florida,
approximately 40 miles southwest of Miami (Figure 1). The refuge is a satellite of National Key Deer
Refuge located 70 miles southwest on Big Pine Key. It is bordered on the east by County Road 905
and on the south by U.S. Highway 1. Card Sound, Barnes Sound, and North Lake Surprise border
the western shoreline of the refuge. The refuge is part of a complex of environmental protected areas
which include Everglades National Park to the northwest, Key Largo Hammock Botanical State Park
to the east, and Card Sound Aquatic Preserve and Biscayne National Park to the north.
REFUGE PURPOSES
Crocodile Lake National Wildlife Refuge was established under authority of the Endangered Species
Act of 1973 and the Fish and Wildlife Act of 1956. The refuge was created specifically to protect
critical habitat for federally listed species. The primary purposes from the enabling legislation are as
follows:
“... to conserve (A) fish or wildlife which are listed as endangered species or
threatened species .... or (B) plants ... 16 U.S.C. ' 1534 (Endangered Species Act of
1973).”
“... for the development, advancement, management, conservation, and protection of
fish and wildlife resources ...16 U.S.C. ' 742f(a)(4) ... for the benefit of the United
States Fish and Wildlife Service, in performing its activities and services. Such
acceptance may be subject to the terms of any restrictive or affirmative covenant, or
condition of servitude ... 16 U.S.C. ' 742f(b)(1) (Fish and Wildlife Act of 1956).”
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Figure 1. Crocodile Lake National Wildlife Refuge location
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ROLE OF CROCODILE LAKE NATIONAL WILDLIFE REFUGE
Crocodile Lake National Wildlife Refuge protects breeding and nesting habitat for the endangered
American crocodile and other wildlife. The refuge is located in north Key Largo and is currently
comprised of 6,700 acres including 650 acres of open water. It contains a mosaic of habitat types,
including tropical hardwood hammock, mangrove forest, and salt marsh. These habitats are critical
for hundreds of plants and animals, including six federally listed species.
The refuge, in conjunction with adjacent state lands, protects the last large areas of habitat in north
Key Largo. Several hundred acres of habitat could have been lost to economic development if the
refuge was not established. Crocodile Lake Refuge is unique in that it is truly a refuge for wildlife.
REFUGE ENVIRONMENT
FISH AND WILDLIFE POPULATIONS, INCLUDING FEDERALLY LISTED SPECIES
Crocodile Lake Refuge is an important ecological niche to conserve several threatened and
endangered species and habitats. The refuge provides habitat for six federally listed threatened and
endangered species, including the American crocodile, Key Largo woodrat, Key Largo cotton mouse,
Schaus swallowtail butterfly, Stock Island tree snail, and eastern indigo snake. The refuge supports
nearly 25 percent of the existing American crocodile population and is one of only three areas in the
United States that provides nesting habitat for the species. Approximately 40 percent of the Key
Largo woodrat and Key Largo cotton mouse reside on the refuge, with the remaining populations
confined to the adjacent Key Largo Hammock Botanical State Park. The inshore waters and
mangrove creeks in and around the refuge provide habitat for the federally endangered West Indian
manatee and five species of federally listed threatened and endangered sea turtles. The refuge is
also a seasonal home to bald eagles, white-crowned pigeons, and other migratory birds. More than
34 state listed wildlife species also call the refuge home.
The refuge is comprised of two globally endangered ecosystems--mangrove wetlands and tropical
hardwood forests. Within the continental United States, these habitat types are found only in extreme
south Florida and the Florida Keys. The tropical hardwood forests contain more than 120 native trees
and shrubs, making this ecosystem one of the most diverse in the world. Nearly 80 percent of the
plant species on the refuge are of West Indian origin. Many of the plant species are listed as
threatened or endangered by the State of Florida, and are also protected by Monroe County.
The mosaic of habitats at Crocodile Lake Refuge supports the federally threatened eastern indigo
snake, as well as the state listed rim rock crowned snake and the Florida Keys mole skink. The
mole skink is a subspecies restricted in distribution to the Florida Keys, while the rim rock
crowned snake is a species that also occurs in the southern reaches of Dade County. These
species are found in several major habitat types, including mangroves, hammock, and driftwood
and tidal wrack along shorelines and islands.
The mangrove wetlands of the refuge serve as important nursery areas for a diversity of fish and
shellfish, with many having recreational and commercial importance. The mangrove wetlands and
hardwood forests of the refuge also support a large number of migratory bird species, including
wading and water birds, shorebirds, waterfowl, and neotropical migratory songbirds.
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TOPOGRAPHY
The refuge is part of the geographic region of high coral keys with maximum elevations of 10 to 12
feet above mean sea level. The intertidal, tidal, and submerged areas of this tract are less than 2 feet
below mean sea level. Natural solution holes, created by the dissolution of the limestone by rainfall,
form depressions in the limestone and can be more than 5 feet in depth. Some of the topography of
the upland and submerged areas has been altered by human activity, such as dredging of deep
canals and basins, filling wetlands and uplands to create adequate elevations for residential
construction, and installation of roads.
GEOLOGY
The geologic formation of the refuge is Key Largo limestone. Built by coral polyps of ancient reef
formations, these remains are similar to the present living coral reefs offshore. Sea level has fluctuated
over time and the land mass of south Florida has been both exposed and submerged by water.
Approximately 120,000 years ago, sea level dropped close to its present level exposing the coral and
allowing for formation of the islands of the Florida Keys. The ancient coral reefs were very large, as
evidenced by Key Largo limestone as much as 145 feet thick in some areas of the upper Keys.
SOILS
Five soil types have been identified on the refuge. They are Pennekamp gravelly muck, Rock
Outcrop-Tavernier complex, Islamorada muck, Key Largo muck, and Udorthents-Urban land complex.
Pennekamp gravelly muck is found in the upland hammock areas typically at the highest elevations.
It is characterized by a thin layer of organic debris and leaf layer over the limestone rock. Soil in this
unit is well drained. In the low intertidal area, the soil unit is Rock Outcrop-Tavernier complex. In this
soil unit, the mangrove tidal swamps are subject to daily flooding by tides causing the soil to be poorly
drained. The exposed limestone rock has weathered into smooth caprock pitted with solution holes
filled with accumulated marl soil. The submerged shallow bottom in Dispatch Slough consists of fine
mud of organic particles and calcareous sediments known as Islamorada muck. In addition to the
Rock Outcrop-Tavernier complex, both Islamorada muck and Key Largo muck are associated with
mangrove tidal swamps. Udorthents-Urban land complex includes constructed upland areas where
land has been altered by dredging and filling for development.
MINERALS
Other than Key Largo limestone, there are no minerals on the refuge.
HYDROLOGY
The primary natural source of fresh water in the Florida Keys is rain. Historically, early settlers collected rain
water in cisterns or used water from wells and solution holes that tapped the small, shallow freshwater
lenses. These lenses form from fresh water held in the ground above sea level during the rainy season.
Until recently, nearshore freshwater upwelling, an extension of the Biscayne Aquifer, occurred in at least
one location on northern Key Largo. Drainage of the Everglades and subsequent canalization of southeast
Florida (including canals in the Florida Keys) resulted in saltwater intrusion into the Biscayne Aquifer and
changed the regional hydrology. Key Largo islands are composed of limestone that is very porous and
does not lead to freshwater lens formation. However, lower Key islands (e.g., Big Pine Key) are composed
of oolite that is much less porous and retains rain water and forms freshwater lenses.
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AIR AND WATER QUALITY
Air pollutants of major concern in Florida are carbon monoxide, lead, nitrogen dioxide, ozone, particulate
matter and sulfur dioxide (Florida Department of Environmental Protection 1999a). The primary sources
of these pollutants are vehicle emissions, power plants, and industrial activities. In 1999, all areas of
Florida were air quality attainment areas (Florida Department of Environmental Protection 1999a). There
are no major industrial operations in the Florida Keys and air quality is consistently good. On occasion,
air quality is reduced briefly by smoke from wildfires in the Everglades.
Water quality is generally good in the Florida Keys. However, nearshore water quality is affected by
storm water runoff and wastewater. On-site septic systems are abundant in the Keys and older
systems do not effectively remove nitrogen and phosphorus from effluent, which leads to
eutrophication of nearshore waters. Similarly, storm water runoff contributes to nearshore water
quality degradation by flushing fertilizers, pesticides, contaminants, and pet waste into the water
during rain events. Most of these negative contributions are directly associated with economic
development. Crocodile Lake Refuge has an overall beneficial effect for nearshore water quality in
north Key Largo since it protects land from economic development and the natural vegetation
effectively traps nutrients and contaminants.
HABITATS
The refuge contains the following five distinct habitat types (Figure 2), along with ruderal and
developed areas.
Tropical Hardwood Hammock
The rockland forests of the refuge are part of the largest West Indian hardwood hammock in the
continental United States. Despite disturbance from development, early settlers, and the construction
of County Road 905, which bisects north Key Largo and separates Key Largo Hammock Botanical
State Park from the refuge, the majority of the hammock is in relatively good condition. Diversity is
high as a result of many successional stages. Mature wild tamarind (Lysiloma latisiliqua), mahogany
(Swietenia mahagoni), gumbo limbo (Bursera simaruba), poisonwood (Metopium toxiferum), and
strangler fig (Ficus aurea) trees dominate the canopy. Understory trees include two rare species of
stoppers: red stopper (Eugenia rhombea) and redberry stopper (Eugenia confusa), as well as white
stopper (Eugenia axillaris), Spanish stopper (Eugenia foetida), milkbark (Drypetes diversifolia), wild
coffee (Psychotria nervosa), soldierwood (Colubrina elliptica), lignum vitae (Guaiacum sanctum), and
torchwood (Amyris elemifera). Several species of bromeliads and orchids, including dollar orchid
(Encyclia boothiana), butterfly orchid (Encyclia tampensis), common wild pine (Tillandsia fasciculata),
twisted air plant (Tillandsia flexousa), silvery wild pine (Tillandsia paucifolia), reddish wild pine
(Tillandsia polystachia), Spanish moss (Tillandsia usneoides), and giant wild pine (Tillandsia
utriculata) can be found on mature trees throughout the hammock.
A number of solution holes in the hammock retain fresh water except under conditions of drought.
These areas support moisture loving plants such as cabbage palm (Sabal palmetto), pond apple
(Annona glabra), and ferns, including leather fern (Acrostichum aureum). The hammock grades into
a narrow strand of transition vegetation found along the hammock margins in areas of lesser
elevation. The hardwood forests in the refuge are host to several endangered animal species,
including the Key Largo woodrat (Neotoma floridana smalli), Key Largo cotton mouse (Peromyscus
gossypinus allapaticola), Schaus swallowtail butterfly (Papilio aristodemus ponceanus), eastern
indigo snake
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Figure 2. Crocodile Lake National Wildlife Refuge habitat
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(Drymarchon corais couperi), and the threatened Stock Island tree snail (Orthalicus reses reses).
Hammock areas also provide important habitat for the state threatened white-crowned pigeon
(Columba leucocephala).
Coastal Rock Barren
Coastal rock barren is a very rare community, occurring in scattered patches along a few shorelines
in the Florida Keys. On the refuge, the coastal rock barren is in good to excellent condition and
occurs between the rockland hammock and the coastal berm/marine tidal swamp. The substrate is
exposed cap rock pitted with small solution holes.
The coastal rock barren forms a zone of varying width on the Gulf side of the rockland hammock.
Prior to refuge acquisition, more land was cleared at the southern end of the refuge for proposed
development. As a result, the northern end of the refuge has a better developed coastal rock barren
community. However, it occurs in areas that are closer to the marine tidal swamp, and therefore,
during the extreme high tides in October, has been inundated with as much as 6 inches of water.
This periodic inundation does not seem to adversely affect the plant species, which are adapted to
harsh conditions. Plant species found in this community include: joewood (Jacquinia keyensis), black
torch (Erithalis fruticosa), saltwort (Batis maritima), black mangrove (Avicennia germinans), white
mangrove (Laguncularia racemosa), saffron plum (Bumelia celastrina), Key thatch palm (Thrinax
morrisii), Florida thatch palm (Thrinax radiata), wild dilly (Manilkara bahamensis), sea lavender
(Limonium carolinianum var. angustatum), Christmas berry (Lycium carolinianum), prickly pear cactus
(Opuntia stricta), limber caper (Capparis flexuosa), and buttonwood (Conocarpus erectus). Exposed
branches of shrubs and small trees are covered with orchids and bromeliads, including dollar orchid
(Encyclia boothiana), butterfly orchid (Encyclia tampensis), reflexed wild pine (Tillandsia balbisiana),
common wild pine (Tillandsia fasciculata), and silvery wild pine (Tillandsia paucifolia). The coastal
rock barren at Key Largo Hammocks needs to be protected from development, the invasion of exotic
species, and poaching of both plant material and driftwood.
Coastal Berm
A narrow coastal berm parallels the fringe of red mangroves (Rhizophora mangle) along portions of
the shoreline of the Port Bougainville Tract. This berm is characterized by a ridge of storm-deposited
debris that is subjected to an accumulation of flotsam. The substrate is coarse calcareous sand,
which has accumulated to an elevation of 1 to 2 feet. A variety of plant associations develop on this
ridge and include dense thickets of large shrubs, small trees, or sparse shrubby vegetation. Such
species include: blackbead (Pithecellobium guadalupense), prickly pear cactus, Spanish stopper,
poisonwood, sea oxeye (Borrichia arborescens), manchineel (Hippomane mancinella), and indigo
berry (Randia aculeata). Unfortunately, this area has been invaded both in historical times and in
recent times by exotic species, particularly seaside portia (Thespesia populnea) and lather leaf
(Colubrina asiatica).
In the areas where the coastal berm occurs, it grades into coastal rock barren and marine tidal
swamp. Because the coastal rock barren is an ecotonal community, plant species found in that
community may also be present in the coastal berm community.
Mangrove Forest
Mangrove forests at the refuge are in excellent condition. Red mangroves are established along the shoreline
with their prop-roots submerged in the water. Typical species found attached to or living near the red
mangrove prop-roots include: snapper (Lutjanus sp.), mosquitofish (Gambusia affinis), oysters (Isognomon
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alatus), barnacles (Lepas anatifera), mangrove crabs (Cardisoma guanhumi), and fiddler crabs (Uca pugilator).
Black mangroves are landward of red mangroves in the intertidal zone, which is subject to tidal movement. To
cope with saltwater inundation and salinity fluctuations, black mangroves extend pneumatophores above the
surface of the soil to aid in gas exchange. White mangroves are often found in association with black
mangroves, but prefer slightly higher ground that is not inundated by daily tides.
Mangrove wetlands support many species of wading birds, such as woodstork (Mycteria americana), white ibis
(Eudocimus albus), and roseate spoonbill (Ajaia ajaja), which frequent the area, particularly in winter months.
Several species of hawks, particularly osprey (Pandion haliaetus), red-shouldered (Buteo lineatus), and red-tailed
(Buteo jamaicensis), and an occasional bald eagle (Haliaeetus leucocephalus), are seasonally observed
over the wetlands, some of which nest in adjacent high hammock trees.
Ruderal and Developed Areas
Ruderal and developed areas can be found throughout the refuge. Ruderal areas include the
abandoned Nike Missile Facility and the old Card Sound Road bed. Some development had taken
place prior to the closure of the property, including a marina with docks, remnants of a fire station and
a maintenance building, a helicopter pad, and several roads.
INVASIVE SPECIES
Florida Keys habitats are continually affected by invasive exotic species. Brazilian pepper, Australian
pine, and lead tree are of particular concern since these plants are fast-growing and crowd out native
vegetation. Many of the dense stands of exotics have been removed from the refuge, but controlling
reestablishment is an ongoing management requirement.
CULTURAL RESOURCES
North Key Largo, which includes the refuge, has been a rich environment for both pre-historic
peoples and early settlers. Prehistoric sites tend to be located near the water, and are chiefly
composed of shell middens. Historical remains are somewhat more widely distributed and more
diverse. The refuge does not have any identified archaeological sites. North Key Largo has been
populated by diverse ethnic groups, including the Timucuan culture, the Caloosa, and settlers from
the Bahamas prior to the influx of Europeans. Early history of north Key Largo shows that Native
Americans inhabited the area between 1600 BC and 1200 AD. They capitalized on the rich seaside
environment. Activities continued in the area until the mid-18th century, which corresponds to the
arrival of the first European settlers. Cultural remains from the pre-historic period consist chiefly of
Glades II and Glades III artifacts, indicating that this was the period of heaviest activity.
Early formal references to north Key Largo include Bernard Romans, an English cartographer who
visited the area in 1776. He commented on an apparent link of Key Largo to the mainland of Florida,
and tried unsuccessfully to find a passage behind Key Largo into Florida Bay.
Shipwrecks were a common occurrence in Key Largo since ships had to navigate treacherous waters
through the dangerous coral reef line. A lightship was placed out at Carysfort Reef and became one of
the most important navigational lights between St. Augustine and Key West. The lightship master,
Captain John Walton, kept a farm house and a small garden with fruit trees at Garden Cove. Another
early settler was Edward Bell, who operated the Carysfort Lighthouse, which replaced the lightship. He
purchased 700 acres near Basin Hills on north Key Largo. There he maintained crops that included
pineapple, sapodilla, and Key lime, as well as other tropical fruits. A hurricane in 1876 destroyed Bell’s
plantation and others in the area. Today, old cisterns, foundations, and remnants of the old fruit tree
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orchards are scattered throughout the hammock. Exotic vegetation, including species grown primarily for
fiber, such as sisal hemp (Agave sisalana) and bowstring hemp, is evidence of earlier settlement.
PARTNERSHIPS AND COORDINATION
The refuge has a 99-year lease to manage 125 acres of hardwood forests, mangrove wetlands, and
disturbed areas owned by the Florida Department of Environmental Protection and located within the
boundaries of the refuge. The tract is managed in accordance with all applicable Florida statutes and
administrative rules, as well as federal regulations governing management of national wildlife refuges.
While the refuge does not have any other formal agreements or partnerships with any other agency
or private organization, it does work closely with many federal, state, and local agencies, as well as
private organizations and groups to address refuge goals and objectives. For example, research of
refuge wildlife is routinely conducted by the University of Florida, which helps further the Service’s
knowledge of the refuge. Additionally, many projects are conducted in conjunction with the state park
across Route 905 since the landscape level of the habitats crosses jurisdictional boundaries.
RECREATIONAL AND COMMERCIAL USE ON THE REFUGE
The Florida Keys receives 3- to 4-million visitors a year, making it one of the most popular tourist
destinations in the United States. Visitors are attracted to warm weather and the beauty of the natural
resources in the Keys. Crocodile Lake Refuge is a closed refuge due to the extreme sensitivity of the
endangered animals and habitats. However, an interpretive butterfly garden was completed in 2001
adjacent to the refuge headquarters to provide limited public use and environmental interpretation and
education. The butterfly garden serves as an outdoor classroom for local elementary schools as part of a
Monroe County 4-H Butterfly Garden School Program developed by the refuge and refuge volunteers.
CURRENT MANAGEMENT PRACTICES
The refuge was established to preserve, protect, and manage habitat for a wide diversity of endangered
species. Even though most available habitat critical for endangered species is now in public ownership,
some endangered species, including the Key Largo woodrat and Key Largo cotton mouse, continue to
decline for unknown reasons. To ensure the long-term survival of these important resources, the refuge
has implemented programs to reverse habitat loss and degradation through aggressive habitat
restoration, protection, and enhancement and to reduce the secondary effects of fire ants, exotic plants,
introduced black rats, and free-roaming cats. The South Florida Multi-Species Recovery Plan is used as
a guide to develop management programs for the refuge. While management focuses on listed species,
recovery actions and activities also benefit other wildlife and fish species.
Major wildlife management programs and projects completed on the refuge since 1997 include:
• Annual population surveys for the American crocodile, Key Largo woodrat, Key Largo cotton
mouse, Schaus swallowtail butterfly, and Stock Island tree snail.
• The Service and the Florida Department of Environmental Protection purchased the last
remaining tracts of land within the acquisition boundaries of the refuge that could be
subject to development under existing Monroe County land use regulations. These sites
consist of approximately 3 acres and include the abandoned cockfighting arena (Corney
Tract), the Gulfstream Trailer Park, and the Intus property.
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• Approximately ¾-mile of Old Card Sound Road located on the refuge was removed; the area
was restored to mangrove wetland; and two sand berms were constructed in the old road bed
to serve as nesting habitat for American crocodiles.
• Over 1,000 wild lime trees, an important larvae host plant for the Schaus swallowtail butterfly,
were planted on the refuge and Key Largo Hammock Botanical State Park to enhance habitat
for this endangered species. The project is ongoing in cooperation with the University of
Florida and Dr. Tom Emmel.
• All mobile homes, structures, and debris were removed from the Gulfstream Trailer Park, with
more than half of the area being restored to hardwood forest. The remaining cleared area is
the site of the refuge headquarters, shop/equipment area, and interpretive butterfly garden.
• The crocodile barrier fence was removed along approximately 1-mile of Card Sound
Road and Highway 905, and wing fences were installed at each of the crocodile culvert
crossings. Due to the design of the barrier fence, crocodile road kills were a larger
problem than before along these roads. The wing fences were installed to help direct
crocodiles to the crossing culverts and appear to be working.
• An interpretive butterfly garden was constructed adjacent to the refuge headquarters to provide
limited public use and environmental education and interpretation. The garden includes an
access path for the disabled, park benches, interpretive signs, and a display pond and waterfall.
The garden is also used as an outdoor classroom for local elementary schools in the area.
• The abandoned cockfighting arena was demolished and removed, thus allowing
approximately 1 acre of hardwood hammock to recover.
• Remnants of seven small support buildings were demolished and the debris pushed into piles
to serve as nesting sites for woodrats.
• The population of the Stock Island tree snail and its range were expanded through the
establishment of four new populations on refuge and state lands in Key Largo and Plantation Key.
• The three missile storage buildings and associated launch pads at the abandoned Nike
missile site were demolished and removed as part of an effort to restore the entire facility
to hardwood forest. Removal of the three buildings will result in restoration of
approximately 5 acres of hardwood forest.
FACILITIES AND STRUCTURES
The refuge has limited support facilities to carry out daily operations. A double-wide, 3-bedroom
trailer serves as the refuge office. Equipment, tools, and supplies are kept in a secure fenced shop
and equipment yard adjacent to the office. Within this fenced-in yard is the refuge’s intern/research
facility consisting of a 2-bedroom mobile home with small office. All these structures are confined to
less than ½-acre of the old Gulfstream Trailer Park.
Several abandoned structures exist throughout the refuge. On the Port Bougainville Tract, which the
refuge leases from the Florida Department of Environmental Protection, stands the remnants of a 2-
bay maintenance facility, a 15-foot high concrete helicopter pad, and a boat basin with degrading
boat docks. At the abandoned Nike missile site, a missile maintenance building is still standing.
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Monroe County maintains a waste transfer station within the refuge acquisition boundary. This facility
is located on the site of the old Key Largo Dump, which was closed in 1983. The Department of
Environmental Protection monitors several test wells on the site for any contamination. Due to the
presence of trash and other debris, the waste transfer station attracts black rats, feral cats, fire ants,
and exotic plants, all of which are detrimental to native wildlife populations on the refuge.
WILDERNESS REVIEW
Refuge planning policy requires a wilderness review as part of the comprehensive conservation
planning process. The Wilderness Act of 1964 defines a wilderness area as an area of federal land
that retains its primeval character and influence, without permanent improvements or human
inhabitation, and is managed so as to preserve its natural conditions and which:
• Generally appears to have been influenced primarily by the forces of nature, with the imprint
of man’s work substantially unnoticeable;
• Has outstanding opportunities for solitude or primitive and unconfined type of recreation;
• Has at least 5,000 contiguous roadless acres or is of sufficient size to make practicable its
preservation and use in an unimpeded condition, or is a roadless island regardless of size;
• Does not substantially exhibit the effects of logging, farming, grazing, or other extensive
development or alteration of the landscape, or its wilderness character could be restored
through appropriate management at the time of review; and
• May contain ecological, geological, or other features of scientific, educational, scenic, or
historic value.
The lands within Crocodile Lake National Wildlife Refuge were reviewed for their suitability in meeting
the criteria for wilderness, as defined by the Wilderness Act of 1964. No lands in the refuge were
found to meet these criteria. Therefore, the suitability of refuge lands for wilderness designation is
not further analyzed in this plan.
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III. Plan Development
PUBLIC INVOLVEMENT AND THE PLANNING PROCESS
Preplanning activities for the Crocodile Lake National Wildlife Refuge comprehensive conservation plan
began in January 2003, with activities such as gathering data and information, meeting with refuge staff,
meeting with intergovernmental partners, visioning, and preparing for the public scoping phase. The core
planning team identified items such as existing and needed data, refuge resources, issues, concerns,
affected members of the public, vision ideas, and public participation issues. As a group, the team
prioritized the most critical issues to be addressed by the refuge over the 15-year life of the plan.
The core planning team, comprised of Service employees and a state Fish and Wildlife Conservation
Commission representative, was assembled and meetings were held in preparation for conducting
the planning effort in advance of public scoping. A notice announcing that the planning process had
begun was published in the Federal Register on May 9, 2003. A public scoping meeting was held on
September 3, 2003, at the Key Largo Public Library, and was successful for gathering input from the
dozen members of the public in attendance. Additional information about the comprehensive
conservation plan and public scoping was provided through informational flyers, a planning update,
articles in the local newspapers, and postings on Fish and Wildlife Service web sites.
A letter that invited participation in the planning process through a variety of means, including public
meetings, letters, faxes, telephone calls, e-mail messages, and personal visits, was mailed to
individuals and organizations on the refuge mailing list. The invitation announced the time and
location of the public scoping meeting, provided other information, and described the purposes of the
refuge. After the public meeting was held, a refuge planning update newsletter was sent to mailing
list recipients and meeting participants, and was also made available at the refuge headquarters.
Members of the Service’s core planning team met periodically to review public comments, data, and
information collected to write the draft plan. Professional reviews of the refuge were conducted to
determine the status, trends, and conditions of refuge resources and facilities. Experts from the
Service, the State of Florida (including Fish and Wildlife Conservation Commission and Department
of Environmental Protection), the Everglades National Park, and the University of Florida participated
in a biological review of the refuge. The information garnered from this review helped the planning
team analyze and develop recommendations for the draft plan and environmental assessment.
The Service sought comments on the draft plan as the next stage of public involvement.
Adjustments, as necessary, were made to the draft plan in preparation for this final plan.
ISSUES AND CONCERNS
During the preplanning and public scoping phases of plan development, a myriad of issues,
concerns, and opportunities were raised by the public, the Service, and other public agencies. Issue
identification is a major factor in determining management goals and objectives, and which projects
the refuge will adopt. In addition to the general public scoping meeting, a series of meetings were
conducted with federal, state, and local governmental agencies. Coordination with governmental
partners and the public is essential to ensure support for the plan and identified projects. While some
of the issues and concerns raised during scoping are significant to the future of the refuge, many are
not within the Service’s management jurisdiction or authority, and some are completely outside of its
control. Several opportunities raised during scoping are addressed by the Service in this plan. A
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Service planning team evaluated the list of issues raised, identified the most significant issues to be
addressed over the next 15 years, evaluated steps to rectify these issues and resource needs, and
measured the impact of plan implementation. The core planning team then developed a list of goals,
objectives, and strategies to shape the management of the refuge for the 15-year life of the plan.
The significant issues are divided into four categories: wildlife and habitat conservation; land
protection and conservation; education and visitor services; and refuge administration. The following
list is a summary of the comments and suggestions provided by the public at the scoping meeting
and other public comments that were received.
WILDLIFE AND HABITAT CONSERVATION
• Needs of threatened and endangered species should be top priority.
• Control of invasive exotic plants is essential.
• Control of fire ants and feral cats is essential.
• Restoration of habitats should be strengthened.
• Consider habitat manipulation experiments to benefit wildlife.
• Maintain closed status of the refuge.
• Coordinate recovery activities with Service’s South Florida Ecological Services Office.
LAND PROTECTION AND CONSERVATION
• Purchase remaining land inholdings within acquisition boundary.
• Investigate a “land swap” with the State of Florida to trade land within each agency’s
respective boundaries.
• Work with Florida Department of Transportation to minimize environmental impacts from
proposed hurricane evacuation road project.
EDUCATION AND VISITOR SERVICES
• Request assistance from Florida Department of Transportation to provide a recreation path
along e 905.
• Allow only staff-led tours of the refuge, if any at all.
• Investigate the possibility of additional public use at the refuge’s headquarters.
REFUGE ADMINISTRATION
• Add an additional full-time biological technician position.
• Continue and increase volunteer workers to assist with refuge projects.
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IV. Management Direction
INTRODUCTION
The Service manages fish and wildlife habitats with the primary focus being conservation of habitat
and wildlife. Crocodile Lake National Wildlife Refuge was created for the purpose of protecting
habitat for federally listed species. The American crocodile was the impetus; however, the refuge
also harbors the Key Largo woodrat, Key Largo cotton mouse, Schaus swallowtail butterfly, Stock
Island tree snail, and eastern indigo snake. Habitats are managed with these species in mind, as
well as other wildlife species, including migratory birds, wading birds, and other snakes and
butterflies.
The Florida Keys is a global biodiversity hotspot and Crocodile Lake Refuge contains a diverse array
of plant and animal species found nowhere else in the continental United States. This plan is
intended to guide management for the next 15 years in order to maintain and enhance refuge
resources for continued vigor in years to come. The goals and objectives in this plan provide a
framework from which future management actions will be based. Conservation of federally listed
species is the overriding priority of all management actions.
All of the goals, objectives, and strategies are in keeping with the purposes of the refuge, and aim to
ensure long-term viability of the fish and wildlife resources.
VISION
Crocodile Lake Refuge is an important area in north Key Largo for biodiversity of the Florida Keys
and North America. The sensitive nature of the habitats and wildlife warrants keeping the refuge
closed to general public use amidst a growing urban landscape. The refuge will be managed to be a
true oasis of protected habitat in an area that has lost much of the habitats that once existed.
Crocodile Lake Refuge will be a model refuge that exemplifies habitat management of hardwood
hammocks, mangrove wetlands, and open water (unique habitats of the Florida Keys) for the benefit of
federally listed threatened and endangered species. Focal species are the American crocodile, Key
Largo woodrat, Key Largo cotton mouse, Stock Island tree snail, and Schaus swallowtail butterfly.
Further, hundreds of other wildlife and plant species will benefit from refuge habitat conservation and
restoration.
MANAGEMENT PLAN SUMMARY
Three goals were developed based on comments from the public and various non-profit and
governmental agencies. Under the following goals, the objectives and strategies outline approaches
to habitat management, exotics control, and coordination of efforts.
1. Provide high-quality habitat, including nesting, resting, foraging, and nursery areas, for the
long-term survival of threatened and endangered species, migratory birds, and other wildlife.
2. Expand on the existing knowledge and database regarding the ecology, biology, and behavior of
threatened and endangered species and those factors affecting their status and long-term
survival.
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3. Develop and implement a comprehensive refuge program that includes providing sufficient staff,
facilities, equipment, and volunteers to protect and manage the natural resources of the refuge.
GOALS, OBJECTIVES, AND STRATEGIES
The goals, objectives, and strategies presented in this plan are based on issues, concerns, and
needs expressed by the planning team, refuge staff, and public. The intent is to achieve the
mandates of the National Wildlife Refuge System Improvement Act, the mission of the National
Wildlife Refuge System, and the establishment purposes of Crocodile Lake National Wildlife Refuge.
GOAL 1
Provide high-quality habitat, including nesting, resting, foraging, and nursery areas, for the long-term
survival of threatened and endangered species, migratory birds, and other wildlife.
Objective 1.1
Maintain, restore, and enhance existing American crocodile nesting habitat.
Discussion: Crocodile Lake Refuge provides for one of three major breeding sites for American
crocodiles in south Florida, the other two sites being Turkey Point Power Plant and along the
southern edge of Everglades National Park. The highest priority for Crocodile Lake Refuge is to
restore and manage nesting habitat that has become less suitable in recent years. Another priority is
to monitor the population by tracking road kills and vital data. However, these kills are considered to
be of such low frequency that there is no need for extraordinary efforts, such as fencing, at this time.
Strategies:
• Control invasive vegetation on existing nesting berms to increase available nesting habitat.
• Treat approximately 3 miles of nesting levee at the Harrison Tract with herbicide to control
invasive vegetation. Herbaceous vegetation will be treated with Roundup Pro, or equivalent,
and those plants with invasive roots or rhizomes will be tilled to make the substrate more
pliable for nesting crocodiles. Woody vegetation will be treated with Garlon 4, or equivalent,
through basal bark application and left standing to decompose naturally. Approximately ½-
mile of nesting levee will be controlled for exotics per year, with the entire nesting levee to be
completed within 6 years of plan adoption.
• Elevate low-lying areas on the existing nesting berms with supplemental nesting material to
prevent saltwater intrusion and flooding of nests.
• Construct 10 elevated nesting mounds along the nesting levee at the Harrison Tract. Mounds
measuring 50′x30′x2′ high will be constructed of suitable nesting material to be determined by
area crocodile biologists. Due to the inaccessibility of the nesting levees, suitable nesting
material will be airlifted to the site by helicopter. Construction of the 10 nesting mounds will
be completed within 5 years of plan adoption. Once constructed, the elevated mounds will be
treated each year with herbicides to control invasive vegetation. Yearly monitoring of the sites
for nesting activity will be conducted to evaluate the success of the program.
• As part of future wetland restoration projects, additional nesting habitat will be created in
restored wetland areas.
25
Objective 1.2
Restore suitable wetland habitat for American crocodiles.
Strategies:
• Remove fill from disturbed areas, such as abandoned roads and fill pads, and restore these
sites to historic wetland elevations where they can recover naturally.
• Remove the remaining portion of the Old Card Sound Road located on the refuge east of the
Card Sound Bridge. Restore the old road bed to historic wetland elevation and allow to
vegetate naturally. This would not only restore the wetland but would eliminate the site from
being used as a launch area for personal watercraft that may disturb crocodiles in the area.
Set a target date of 10 years to complete this project.
• Coordinate and cooperate with the Florida Keys Mosquito Control District to initiate,
implement, and complete the Jewfish Creek Restoration Project on property it owns near
Jewfish Creek. This project would involve the removal of approximately 1 mile of old
abandoned road that traverses mangrove wetlands. The road bed and all associated fill
would be removed and the area restored to historic wetland elevation. A nesting berm would
be placed in the road bed near a tidal creek to serve as a possible nest site for American
crocodiles. A target date of 5 years would be set to complete this project.
• Coordinate and cooperate with other governmental agencies, environmental organizations, and
local landowners to purchase and restore 12 acres of filled and disturbed wetlands located north
of Lake Surprise as part of the Lake Surprise Restoration Project. This project would involve
removing the majority of fill and restoring the area to historic wetland elevation and creating
additional habitat for crocodiles. A portion of the fill, approximately 2,000′x100′, would remain to
serve as a base for the construction of nesting sites for American crocodiles and to support an
access road to these sites. A target date of 10 years would be set to complete this project.
• Create a sand/gravel nesting berm within the proposed Jewfish Creek Wetland Restoration
Project. The nesting berm should be 50′x25′x3′ high and constructed of suitable nesting
material to be determined by area crocodile biologists.
• Create a nesting berm within the proposed Lake Surprise Wetland Restoration Project. The
nesting levee should be 2,000′x50′x3′ high and constructed of suitable nesting material on
existing fill within the project area.
Objective 1.3
Within 6 years of the date of this plan, develop a nesting, nest production, population trend, and road
mortality monitoring plan for the American crocodile.
Strategies:
• Coordinate with cooperative agencies, organizations, and groups, such as the Florida Fish
and Wildlife Conservation Commission and the University of Florida, to develop and conduct
population surveys of the American crocodile to determine distribution, abundance, and
trends, as well as to determine the effectiveness of management programs and actions.
26
• Continue to coordinate with Florida Fish and Wildlife Conservation Commission to complete
nesting and hatchling surveys on the refuge each year. The Commission has conducted nest
and hatchling surveys on the refuge for the past 27 years and maintains the database for all
information. It will continue to take the lead in this program as long as its resources will allow.
• Continue to coordinate with the University of Florida to expand crocodile surveys on the
refuge. This would include expanded surveys of the Harrison Tract, Crocodile Lake area, and
the refuge shoreline of Lake Surprise, Barnes Sound, and Card Sound. The refuge would
assist with this program by providing staff to help with the surveys both on- and off-refuge.
The University would provide all other needed equipment and supplies.
• Surveys of American crocodiles should include, but not be limited to, nest counts,
hatchling surveys, and overall population censuses and should include all suitable
habitats on the refuge, as well as portions of the Biscayne Bay Estuary, such as Lake
Surprise, Barnes Sound, and Card Sound.
• Continue yearly crocodile nest surveys on the Harrison Tract and Card Sound Road
Restoration area, as well as any new nesting areas created as part of future wetland
restoration projects. These surveys provide important information on nest site
preference and nesting success.
• Continue yearly hatchling surveys within areas of the refuge where nesting has been
documented. Attempts would be made to catch and mark each hatchling observed and to
collect important data, including length, weight, location of capture, etc. The data collected
would provide important insights in recruitment, age class distribution, and movement patterns
of crocodile populations on the refuge and surrounding areas.
• Continue to assist the University of Florida with its quarterly crocodile surveys conducted
along the refuge shoreline adjacent to Lake Surprise, Barnes Sound, and Card Sound. These
quarterly surveys provide important information on population size/trends, recruitment, and
movement patterns of crocodiles within the refuge.
• With the assistance of the University of Florida, expand the monitoring program for crocodiles
on the refuge to include quarterly surveys of the Harrison Tract and Crocodile Lakes area.
• Continue to monitor and document crocodile road kills on U.S. Highway 1 and Card Sound
Road in the Key Largo area. Collect data on each road kill including total length, snout/vent
length, weight (if possible), location hit, date, marked or unmarked crocodile, and general
condition of the animal. This would provide important information on movement patterns and
population size/trends, as well as overall health of the population. All information would be
provided to appropriate agencies.
• Establish a standard protocol for data collection on crocodiles hit by vehicles.
Objective 1.4
Actively manage Key Largo woodrat habitat, including nesting, resting, and foraging areas for the
long-term survival of the species.
Discussion: Crocodile Lake Refuge contains some of the last remaining tropical hardwood hammocks
in Key Largo. The woodrat once ranged throughout Key Largo but is now restricted to the refuge and
adjacent state lands due to loss of habitat. Recent sampling efforts revealed a drastic drop in the
woodrat population. This led the Service’s South Florida Ecological Services Office to initiate a captive
breeding program in order to prevent immediate extinction. The refuge role is to maintain and enhance
habitat and assist the Ecological Services’ office with the ultimate release of captive-bred woodrats.
27
Strategies:
• Create artificial nest sites from coral rubble and other debris and place them in suitable
woodrat habitat.
• Use large concrete rubble or limestone boulders to create artificial nest structures in open areas
of the refuge. Rubble piles should be a minimum of 6′ tall x 15′ wide so as to provide ample
sources of possible nest sites. To avoid damage to existing hardwood forests, the rubble piles
would be placed in disturbed areas of the refuge, such as the Port Bougainville Tract and the Nike
missile site. Twenty nesting structures would be constructed within the next 5 years.
• Restore hardwood forests. Remove abandoned buildings and other structures at the Port
Bougainville Tract and Nike missile site and allow natural revegetation.
• Demolish the maintenance building and concrete helicopter pad at the Port Bougainville Tract,
and the missile maintenance building at the Nike missile site. The construction rubble would
remain on-site and be pushed into piles to serve as nesting sites for the endangered Key
Largo woodrat. The restoration would result in approximately 1 acre of tropical hardwood
forest to serve as important habitat for the Key Largo woodrat. Demolition of existing
structures would be completed within 5 years.
• Create hammock habitat by filling areas within historic hardwood forests that were dredged or mined.
• Fill the 1.5-acre Keystone Pit and restore the area to its historic elevation. Fill can include
concrete/concrete block, crusted limestone (marl), or any other suitable soil substrate. Due to
the size of this project, it is expected to take 15 years to restore the Keystone Pit.
• Restore and enhance habitat by controlling invasive exotic plants within the refuge and along
public rights-of-way and easements. Coordinate with adjacent landowners to control exotic
plants on non-refuge lands that may serve as habitat for woodrats, or that may serve as a
possible seed source for re-infestation of refuge lands.
• Control exotic plants mechanically (pulled by hand) or chemically with the appropriate herbicide.
Woody vegetation would be treated with Garlon 4, either as a basal bark application or cut stump
application. Herbaceous vegetation would be treated with Roundup Pro, or other appropriate
herbicide. In most cases, the vegetation would remain on site to decompose naturally.
• Continue follow-up control of exotic plants in problem areas, including Port Bougainville Tract,
Whiskey Bottle Pit/Keystone Tract, county auto salvage site, and the Nike missile site. This
would be done yearly until all exotics and associated seed sources are depleted (5-6 years).
• Continue yearly maintenance control of exotics along County Road 905 and Card Sound
Road rights-of-way that transect the refuge. These easements have been treated yearly since
1999, and require minimal control to keep them free of exotics.
• Coordinate and cooperate with the Florida Keys Electric Cooperative to control invasive exotic
plants along its power line easement adjacent to the refuge. The refuge would provide staff
time to assist the Cooperative in pulling or treating exotics within the easement. The
Cooperative would provide the herbicide used for the treatments.
• Survey and control exotics along the transitional upland corridor of the refuge (hardwood
forest/wetland interface). Exotics identified in this area would be pulled by hand or treated with a
basal bark application of Garlon 4. Initial application would be completed within 2 years.
• Enhance habitat by controlling fire ants within the refuge and along adjacent public rights-of-way
and easements.
28
• Continue with feral and free-roaming cat control.
• Continue to investigate the effectiveness of controlling fire ants along County Road 905 using
long-lasting broadcast baits such as Extinguish. Currently, the refuge is treating 9 miles of
County Road 905 twice a year with Extinguish fire ant bait and initial results look promising. If
Extinguish or other fire ant controls are effective, expand the control program to other areas
that exhibit fire ant infestation.
• Expand fire ant surveys to include abandoned roads and other open areas to determine
extent of fire ant infestation on the refuge. Areas on which to focus include Port Bougainville,
Keystone/Whiskey Bottle area, county auto salvage site, and Nike missile site.
Objective 1.5
Within 5 years of the date of this plan, develop a nesting, nest production, and population trend
monitoring plan for the Key Largo woodrat.
Strategies:
• Assist the Service’s South Florida Ecological Services Field Office with development and
implementation of population surveys of the Key Largo woodrat to determine distribution,
abundance, trends, and habitat preferences, as well as to determine the effectiveness of
management programs and actions. The Ecological Services’ office has taken the lead on
this program and, where practical, the refuge would provide support (e.g., supplies,
equipment, housing, limited staff, and technical assistance) to help fulfill monitoring
responsibilities.
• Coordinate with Ecological Services to monitor the effects of habitat management programs
and activities on woodrats.
• Integrate extensive woodrat surveys developed and initiated by Ecological Services. This
would include conducting woodrat surveys in conjunction with management programs, such
as fire ant/cat eradication, woodrat nesting structure development, and habitat
modification/alteration, in an effort to determine the most effective method to safeguard and
improve habitat conditions for woodrats.
Objective 1.6
Actively manage Key Largo cotton mouse habitat including nesting, resting, and foraging areas for
the long-term survival of the species.
Discussion: The cotton mouse once ranged throughout Key Largo but is now restricted to the
refuge and adjacent state lands due to loss of habitat. The cotton mouse inhabits tropical hardwood
hammock but has broader requirements than the Key Largo woodrat and thus the population is
steady. The refuge aims to manage habitats for the long-term survival of the species.
Strategies:
• Restore hardwood forests. Remove abandoned buildings and other structures at the Port
Bougainville Tract and Nike missile site and allow natural revegetation.
29
• Demolish the maintenance building and concrete helicopter pad at the Port Bougainville Tract
and the missile maintenance building at the Nike site. The construction rubble would remain
and be pushed into piles to serve as nesting sites for the endangered Key Largo cotton
mouse. The restoration would result in approximately 1 acre of tropical hardwood forest to
serve as important habitat for the Key Largo cotton mouse. Demolition of existing structures
would be completed within 5 years.
• Create hammock habitat by filling areas within historic hardwood forests that were dredged or mined.
• Fill the 1.5-acre Keystone Pit and restore the area to historic elevation. Fill can include
concrete/concrete block, crusted limestone (marl), or any other suitable soil substrate. Due to
the size of this project, it is expected to take 15 years to restore the pit.
• Restore and enhance habitat by controlling invasive exotic plants within the refuge and along
public rights-of-way and easements. Also coordinate with adjacent landowners to control
exotic plants on non-refuge lands that may serve as habitat for cotton mice, or that may serve
as a possible seed source for re-infestation of refuge lands.
• Exotic plants would be controlled mechanically (pulled by hand) or chemically with the
appropriate herbicide. Woody vegetation would be treated with Garlon 4, either as a basal
bark application or cut stump application. Herbaceous vegetation would be treated with
Roundup Pro, or other appropriate herbicide. In most cases, the vegetation would remain on
site to decompose naturally.
• Continue follow-up control of exotic plants in problem areas, including Port Bougainville
Tract, Whiskey Bottle Pit/Keystone Tract, county auto salvage site, and the Nike missile
site. This would be done yearly for a period of 5-6 years until all exotics and associated
seed sources are extirpated.
• Continue yearly maintenance control of exotics along the County Road 905 and Card Sound
Road rights-of-way that transect the refuge. These easements have been treated yearly since
1999 and require minimal control to keep them free of exotics.
• Coordinate and cooperate with the Florida Keys Electric Cooperative to control invasive exotic
plants along its power line easement adjacent to the refuge. The refuge would provide staff
time to assist the Cooperative in pulling or treating exotics within the easement. The
Cooperative would provide the herbicide used for the treatments.
• Survey and control exotics along the transitional upland corridor of the refuge (hardwood
forest/wetland interface). Exotics identified in this area would be pulled by hand or treated
with a basal bark application of Garlon 4. Initial application would be completed within 2
years.
• Enhance habitat by controlling fire ants within the refuge and along adjacent public rights-of-
way and easements.
• Continue to investigate the effectiveness of controlling fire ants along County Road 905 using
long-lasting broadcast baits such as Extinguish. Currently, the refuge is treating 9 miles of
County Road 905 twice a year with Extinguish fire ant bait and initial results look promising. If
Extinguish or other fire ant controls are effective, the program would be expanded to other
areas that exhibit fire ant infestation.
• Expand fire ant surveys to include abandoned roads and other open areas to determine
extent of fire ant infestation on the refuge. Areas to focus on include Port Bougainville Tract,
Whiskey Bottle/Keystone Tract, county auto salvage site, and Nike missile site.
30
Objective 1.7
Within 5 years of the date of this plan, develop a nesting, nest production, and population trend
monitoring plan of the Key Largo cotton mouse.
Strategy:
• Assist the Service’s South Florida Ecological Services Field Office with the development and
implementation of population surveys of the Key Largo cotton mouse to determine distribution,
abundance, trends, and habitat preferences, as well as to determine the effectiveness of
management programs and actions. Ecological Services would take the lead on this program
and, where practical, the refuge would provide assistance (e.g., supplies, equipment, housing,
limited staff, and technical assistance).
Objective 1.8
Actively manage Schaus swallowtail butterfly habitat including nesting, resting, and foraging areas in
order to increase the population size and ensure long-term survival of the species.
Discussion: The Schaus swallowtail butterfly is a large dark brown and yellow butterfly that
historically occurred in hardwood hammocks from south Miami to Lower Matecumbe Key, Florida.
The loss of habitat to development has drastically restricted the current range to north Key Largo and
south Miami. Schaus swallowtails are exclusively found in hardwood hammocks, which contain plants
essential for reproduction and feeding. Crocodile Lake Refuge is important since it protects one of
the last large hammocks in the Keys and south Florida. Managing the refuge for this species also
benefits other butterfly species, such as the Miami blue, hairsteak, and skipper. Strategies for habitat
restoration activities that are specifically defined for the Key Largo woodrat and cotton mouse are the
same for Schaus swallowtail butterflies. Please refer to the aforementioned habitat strategies for
more details about restoration of forests and control of exotics.
Strategies:
• Continue to prohibit the use of broad spectrum adulticides by the Florida Keys Mosquito
Control District to control mosquitoes on the refuge.
• Cooperate with the Florida Keys Mosquito Control District in developing improved methods of
mosquito control that reduce the need for broad spectrum adulticides and minimizes impacts
to natural resources of the area.
• Enhance habitat for the Schaus swallowtail butterfly by planting the larvae host plants of the
butterfly.
• Continue to plant wild lime and torchwood, two important larvae host plants for the Schaus
swallowtail butterfly, along abandoned roads and other disturbed areas adjacent to suitable
butterfly habitat. Sites to consider for future plantings include Port Bougainville Tract, the
county auto salvage site, and the Nike missile site.
• Continue to coordinate plantings with the University of Florida, which will provide wild lime
trees and the labor needed to plant and establish the trees on the refuge. Set a target of 50-
100 trees established per year on the refuge for the next 5 years.
31
Objective 1.9
Within 10 years of the date of this plan, develop a nesting, nest production, and population trend
monitoring plan for the Schaus swallowtail butterfly.
Strategies:
• Coordinate with the University of Florida, cooperative agencies, organizations, and groups to
develop and conduct population surveys of the Schaus swallowtail butterfly to determine
distribution, abundance, and trends, and to determine the effectiveness of management
programs and actions.
• Continue to coordinate with the University of Florida to complete Schaus swallowtail butterfly
surveys on the refuge each year. The University has conducted these surveys on the refuge
since the early 1990s and maintains the database for all information. The University will
continue to take the lead in this program as long as its resources will allow.
• The refuge will expand surveys on the refuge for the Schaus swallowtail butterfly that will
enhance and complement the work presently being done by the University of Florida. Areas
to survey would include the Port Bougainville Tract, Harrison Tract, county auto salvage site,
and Nike missile site.
• Surveys should include adult flight counts and egg/larvae surveys on suitable habitat
throughout North Key Largo, including Key Largo Hammock Botanical State Park.
• Both flight counts and egg/larvae surveys will be conducted along abandoned roads and
disturbed areas of the refuge where wild lime trees have been planted. The lime trees not
only attract female Schaus swallowtail butterflies looking for host plants, but serve as
important survey sites to monitor egg and larvae abundance.
Objective 1.10
Actively manage Stock Island tree snail habitat, including nesting, resting, and foraging areas for the
long-term survival of the species.
Discussion: The Stock Island tree snail is an arboreal snail found in hardwood hammocks in the
Florida Keys. The snail historically occurred on Stock Island and Key West where it has been
virtually extirpated. Habitat loss and a significant decline in the original Stock Island population
led snail collectors to move snails to other hammocks throughout the Keys. The translocation of
snails successfully prevented extinction of the species, but several of the few remaining
populations are at risk due to continuing habitat loss to development. Crocodile Lake Refuge
contains one of the last established populations of the Stock Island tree snail. Strategies for
habitat restoration activities that are specifically defined for the Key Largo woodrat and cotton
mouse are the same for Stock Island tree snails. Please refer to the aforementioned habitat
strategies for more details about restoration of forests and control of exotics.
Strategies:
• Continue to prohibit the use of broad spectrum adulticides by the Florida Keys Mosquito
Control District to control mosquitoes on the refuge.
• Cooperate with the Florida Keys Mosquito Control District in developing improved methods of
mosquito control that reduce the need for broad spectrum adulticides and minimizes impacts
to natural resources of the area.
32
Objective 1.11
Within 10 years of the date of this plan, develop a nesting, nest production, and population trend
monitoring plan for the Stock Island tree snail.
Strategies:
• Coordinate with other cooperative agencies, organizations, and groups to develop and
conduct population surveys of the Stock Island tree snail to determine distribution,
abundance, and trends, and to determine the effectiveness of management programs and
actions.
• Continue to coordinate and cooperate with the Florida Keys Electric Cooperative in the
identification of Stock Island tree snails found during routine power line corridor maintenance.
The Cooperative is knowledgeable in the identification of Stock Island tree snails and notifies
the refuge immediately upon discovery of snails that have been displaced by their
maintenance activities. The Cooperative also has expertise in the proper protocol for
transplanting of displaced snails to adjacent trees.
• Coordinate and cooperate with the Florida Fish and Wildlife Conservation Commission in
developing and implementing snail surveys for those populations relocated in 2000 on their
Dove Creek and Snake Creek Management Areas located in Key Largo and Plantation Key.
Due to the time needed for these populations to increase to a size large enough to be readily
detected by surveys, this monitoring will not be initiated until 2005.
• Continue refuge surveys of Stock Island tree snails in the two locations where they are known
to occur on the refuge. Continue to conduct exploratory surveys on other areas of the refuge
that contain suitable tree snail habitat.
• Surveys should include summer snail counts on areas of the refuge supporting known
populations of Stock Island tree snails, and should be coordinated with Ecological Services to
complete surveys of known tree snail populations off-refuge, including introduced populations
on Key Largo and Plantation Key.
• Snail surveys will be conducted each year during the summer months with emphasis on August-
September, the wettest months of the year, when snails are most active and easiest to survey.
Objective 1.12
Actively manage eastern indigo snake habitat, including nesting, resting, and foraging areas for the long-term
survival of the species. Strategies for habitat restoration activities that are specifically defined for the
Key Largo woodrat and cotton mouse are the same for eastern indigo snakes. Please refer to the
aforementioned habitat strategies for more details about restoration of forests and control of exotics.
Discussion: The eastern indigo snake is a large, black, non-venomous snake found in the southeastern
United States and throughout Florida. It is believed that in Key Largo the snakes are restricted to north
Key Largo hammocks, which are primarily found at Crocodile Lake Refuge and the state botanical park.
Confirmed sightings of the snakes are rare and occur every 5 to 10 years. Refuge management and
restoration of hardwood hammocks benefit this species since it is exclusive to hammocks.
33
Objective 1.13
Within 10 years of the date of this plan, develop a nesting, nest production, and population trend
monitoring plan for the eastern indigo snake.
Strategies:
• Due to the small population size of this species on the refuge and the difficulty in surveying
snakes, no formal monitoring program will be developed for the eastern indigo snake.
• Presence/absence data will be collected by documenting any road kills along public roads and
through observations made by staff and other persons during routine refuge operations.
• Coordinate with staff of the Key Largo Hammocks Botanical State Park and the Monroe
County road maintenance crew to receive any reports on road kills of eastern indigo snakes
along County Road 905 and Card Sound Road. The state park conducts road kill surveys
along these roads and the county’s road crew conducts regular maintenance of these roads,
making these two entities the ones most likely to discover and document road kills.
Objective 1.14
Coordinate habitat management activities with the Service’s South Florida Ecological Services Office
to support threatened and endangered species recovery efforts.
Strategies:
• Coordinate and cooperate with Ecological Services in the review of refuge habitat
management programs and actions to ensure compliance with federal, state, and local
regulations, and to ensure that these programs and projects contribute to the health and long-term
survival of threatened and endangered species.
• Submit all habitat management plans and actions to Ecological Services for review to ensure
compliance with the Endangered Species Act and other Service regulations. Consult with the
Army Corps of Engineers, the Florida Department of Environmental Protection, and the
Florida Fish and Wildlife Conservation Commission to ensure all management activities are in
accordance with applicable federal and state regulations.
• Where practical, provide assistance to Ecological Services in the form of supplies, equipment,
housing, and staff support needed to identify and complete recovery actions for listed species.
Objective 1.15
Gather data and information necessary for ensuring sustainable white-crowned pigeon populations in
and around the refuge in north Key Largo by 2010.
Strategies:
• Determine nesting sites and evaluate their protective status with respect to access by
predators and disturbance from recreationists.
• Evaluate response of fruit-producing species and pigeon foraging to experimental habitat
manipulations on Key Largo.
34
Objective 1.16
Acquire remaining privately owned lands within the refuge acquisition boundary (Figure 3).
Strategies:
• Within 2 years of the date of this plan, identify privately owned parcels within the refuge
acquisition boundary and work with refuge partners to secure funding to acquire those
parcels.
• Develop a GIS database and related maps of all privately owned parcels within the refuge’s
boundary. The database should include the names of the property owners, including
addresses and phone numbers, parcel sizes, and habitat types found on the property.
• Identify possible environmental foundations and organizations that might be sources of
funding for future land acquisitions. Also, identify private citizens who might be sources of
funding for future land acquisitions.
GOAL 2
Expand on the existing knowledge and the database regarding the ecology, biology, and behavior of
threatened and endangered species and those factors affecting their status and long-term survival.
Objective 2.1
Encourage research on biology and life history of threatened and endangered species, including
aspects of reproductive success, productivity, dispersal, and movement patterns.
Strategies:
• Coordinate with Ecological Services to conduct research on these species utilizing Service
biologists, universities, and/or independent researchers.
• Provide logistic support for research efforts by supplying equipment, supplies, housing, and
limited staff, whenever possible.
Objective 2.2
Encourage research on habitat requirements and preferences of threatened and endangered
species.
Strategies:
• Coordinate with Ecological Services to conduct research on wildlife habitats utilizing Service
biologists, universities, and/or independent researchers.
• Provide logistic support for research efforts by supplying equipment, supplies, housing, and
limited staff, whenever possible.
•
Coordinate research with proposed habitat management programs and activities to determine
impacts on threatened and endangered species.
Objective 2.3
Encourage research on captive breeding of Key Largo woodrats to improve the success of existing
and future breeding efforts.
35
Figure 3. Crocodile Lake National Wildlife Refuge land ownership
36
Strategies:
• Coordinate with Ecological Services to conduct research on woodrat husbandry utilizing
Service biologists, universities, and/or independent researchers.
• Provide logistic support for research efforts by supplying equipment, supplies, housing, and
limited staff, whenever possible.
GOAL 3
Develop and implement a comprehensive refuge program that includes providing sufficient staff,
facilities, equipment, and volunteers to protect and manage the natural resources of the refuge.
Discussion: The refuge requires few staff since it is closed to public use and contains minimal
infrastructure to maintain. The refuge is a satellite of the National Key Deer Refuge and receives
maintenance and staff support on an as-needed basis. However, a full-time biological technician is
necessary to assist with annual wildlife surveys, censuses, and habitat management.
Objective 3.1
Staff the refuge with a full-time manager, a full-time biologist, a full-time biological technician, and a
seasonal biological technician to implement refuge programs and activities needed to fulfill the goals
and objectives of the refuge.
Strategies:
• Secure refuge funding for a full-time biologist and a seasonal biological technician.
Provide part-time and seasonal staff to assist with the completion of important refuge programs and activities
Objective 3.2
Develop and maintain an active volunteer program on the refuge.
Strategies:
• Continue to work with the refuge friend’s group, FAVOR, to provide assistance in the
management and growth of the volunteer organization.
• Develop and implement volunteer projects and activities that not only help fulfill refuge goals and
objectives but also instill in the volunteers a sense of pride, accomplishment, and stewardship.
37
V. Plan Implementation
INTRODUCTION
As required by the National Wildlife Refuge System Improvement Act of 1997, the Service will
manage all refuges in accordance with an approved comprehensive conservation plan, which, when
implemented, will achieve refuge purposes; help fulfill the National Wildlife Refuge System mission;
maintain and, where appropriate, restore the biological integrity, diversity, and environmental health
of the refuge; and meet other mandates.
PROPOSED PROJECTS
The proposed projects reflect the basic needs identified by Service staff, the public, and planning team
members for the management of fish and wildlife populations, habitats, visitor services, general
administration, land protection, and conservation. Among these projects is a list of step-down plans to be
developed. The refuge operates under a number of step-down plans, which are individual and specific
management plans. Some specific plans may need revisions, while others will need to be developed.
Eleven projects were developed based on the strategies designed to achieve plan objectives. These
projects are subject to revision at least every 15 years, but may be amended earlier based on
updated information. Estimated costs of the projects have been included (Table 1).
PROJECT 1: INVASIVE EXOTIC PLANT CONTROL
The refuge has aggressively targeted invasive exotic plants for the past several years and has
reached a general maintenance level. However, there is an ongoing need to monitor and remove
exotics. Key Largo has a considerable seed source of Brazilian pepper, lead tree, and Australian
pine that is continuously distributed by birds and raccoons. Further, exotic swamp fern needs to be
periodically eradicated from crocodile nesting berms since it prevents successful nesting. The
estimated recurring cost for this activity is $15,000 per year.
PROJECT 2: INVASIVE EXOTIC PEST CONTROL
Fire ants are an aggressive ant species introduced from South America that raid woodrat and cotton
mouse nests and kill newborns. Nesting occurs along County Road 905, which runs through the
refuge. Fire ant control is an ongoing management action that requires the use of an approved
insecticide. Several treatments a year are required along approximately 12 miles of road on both
sides. The estimated recurring cost for this activity is $5,000 per year.
PROJECT 3: FERAL AND FREE-ROAMING CAT CONTROL
Feral and free-roaming cats are of considerable concern on the refuge, since they prey on woodrats and
cotton mice. Control efforts involve live-trapping and taking the cats to animal shelters. The refuge does
not kill any cats. There are a few known hotspots for cat activity on the refuge and trapping efforts are
undertaken when needed. The South Florida Ecological Services Field Office is the lead in this effort
since the South Florida Multi-Species Recovery Plan (1999) requires this activity for the successful
recovery of the Key Largo woodrat. Estimated recurring cost for this activity is $15,000 per year.
38
PROJECT 4: CROCODILE NESTING BERM REPLENISHMENT
Nesting berms for crocodiles consist of organic peat that naturally decomposes over time. Currently,
many of the berms have become unsuitable for nesting and require replenishment of the peat.
Access to the berms is only available by water in shallow-draft boats. This makes transport of large
quantities of peat extremely difficult. Using a helicopter with a transport bucket would be the most
effective method to bring new peat to the berms. The estimated one-time cost is $75,000 with a
recurring cost of $1,000 per year for maintenance.
PROJECT 5: HABITAT RESTORATION
The refuge has several areas that consist of cleared and disturbed habitats. Old roads, borrow pits,
and the Nike missile site are in need of restoration. Funding is typically the factor that delays
restoration projects, since removal of fill and debris is expensive and labor-intensive. The refuge has
accomplished a considerable amount of restoration but is not yet finished and plans to complete all
restoration areas within 10 years of the date of this plan. The estimated cost to complete all
restoration is $500,000 with a recurring cost of $1,000 per year for 5 years after completion.
PROJECT 6: WOODRAT ARTIFICIAL NEST SITES
The Key Largo woodrat is a ground-nesting species that prefers to nest in rubble or brush piles.
Woodrats also heavily utilize illegally dumped trash (e.g., cars, refrigerators, and washing machines)
for nesting. However, once the thin metal cases of these items rust away the woodrats abandon the
sites. The refuge has removed almost all of the dumped trash and plans to create artificial nesting
sites for the woodrat using natural materials, such as coral rocks. The estimated initial cost is
$50,000 with a recurring cost of $1,000 per year.
PROJECT 7: SCHAUS SWALLOWTAIL BUTTERFLY PLANTS
The Schaus swallowtail butterfly requires specific plants for food and for egg laying. The refuge
wants to plant more of these plant species in order to increase the butterfly population. These
plantings will also benefit other butterflies on the refuge and assist with some restoration areas. The
estimated initial cost is $30,000 with an estimated recurring cost of $1,000 per year.
PROJECT 8: MONITORING AND POPULATION SURVEYS
A systematic survey of the refuge’s threatened and endangered species will be conducted on a
recurring basis in order to determine status and trends of the species. Periodic surveys of other
species will also occur in order to determine if habitat management changes are needed. Monitoring
and surveys are ongoing needs that warrant a dedicated biological technician for the refuge. The
estimated recurring cost is $5,000 per year.
PROJECT 9: LAND ACQUISITION
A few land inholdings remain within the refuge acquisition boundary (Figure 3). The refuge would like
to acquire these inholdings in order to complete the refuge and protect the lands from development.
Land values change rapidly in the Keys, thus the estimated costs will change constantly. The faster
the inholdings can be purchased, the lower the cost. The current estimated cost is $1,000,000 to
$3,000,000 and increasing substantially each year.
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PROJECT 10: VOLUNTEER PROGRAM
The refuge relies on volunteers for many of its annual management activities, such as crocodile
nesting surveys, exotic control, and habitat management. The refuge wants to recruit more
volunteers to assist with projects. Additional funding is needed to provide supplies for the volunteer
program. The estimated recurring cost is $3,000 per year.
PROJECT 11: BUTTERFLY GARDEN AND INTERPRETIVE MATERIALS
Refuge volunteers developed a butterfly garden at the refuge headquarters to provide visitors with an
interpretive experience. The garden is universally accessible and illustrates many of the plants found on
the refuge. Additional interpretive signs and kiosks are needed to complete the project, and information
needs to be updated periodically. The interpretive materials will help visitors understand why the refuge
is closed to public access. The initial estimated cost is $5,000 with a recurring cost of $1,000.
Table 1. Cost summary of projects
Project Initial cost Recurring costs
per year
Invasive exotic plant control 15,000 5,000
Invasive exotic pest control 5,000 5,000
Feral cat control 15,000 10,000
Crocodile nesting berm replenishment 75,000 1,000
Habitat Restoration 500,000 1,000
Woodrat artificial nest sites 50,000 1,000
Schaus swallowtail butterfly plants 30,000 1,000
Monitoring and population surveys 5,000
Land Acquisition 1,000,000 to 3,000,000
Volunteer program 3,000
Butterfly garden and interpretive
materials
5,000 1,000
Full-time biologist (GS-11) ~80,000 60,000
Full-time biological technician (GS-9) ~70,000 50,000
Seasonal biological technician ~35,000 25,000
Full-time refuge manager (GS-12) 70,000
TOTAL
1,000,000 to 3,600,000
($880,000 without land
acquisition)
238,000
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STAFFING NEEDS
Crocodile Lake National Wildlife Refuge is a satellite refuge of the National Key Deer Refuge with its
headquarters on Big Pine Key. The refuge is staffed by a refuge manager who handles daily
activities. To conduct large projects, National Key Deer Refuge staff travel to Crocodile Lake Refuge
to provide assistance. However, since the refuges are 2 hours apart, it is not feasible to send staff on
a daily basis. The addition of a full-time biologist, a biological technician, and a seasonal biological
technician will be required for the refuge to achieve the goals and objectives outlined in this plan.
The estimated cost for a full staff would be $205,000 per year.
STEP-DOWN PLANS
Service policy (Fish and Wildlife Service Manual, Chapter 602 FW 4, Step-Down Management
Planning) requires that specific management plans be developed for each refuge. Some plans
require annual revisions and others are on a 5- to 10-year schedule for revision. Refuge staff will
continue to seek public and professional input in the development, revision, and implementation of
step-down plans. Some of these plans are already in place, while others need to be developed.
Step-down plans that require development, some level of modification, or updating to implement this
plan are listed below:
• Hurricane Evacuation Plan (2000)
• Public Use Plan (2000)
• Fire Management Plan (2000)
• Habitat Management Plan (included in this plan)
• Law Enforcement Plan (2004)
PARTNERSHIP OPPORTUNITIES
To achieve the goals and objectives of this plan, maintaining existing partnerships and developing
new ones with a variety of resource agencies, organizations, and individuals are essential.
Partnerships help enable the refuge to fulfill plan objectives and reduce costs.
The Florida Department of Environmental Protection is a key refuge partner since there is a state
park directly across County Road 905. The state park shares the same habitats as the refuge and is
essential in helping the refuge manage species, such as the Key Largo woodrat and cotton mouse.
Another major partner is the refuge friends group, FAVOR, which provides excellent volunteer help
with numerous refuge projects. Without volunteer help, the refuge would struggle to complete refuge
management projects.
MONITORING AND ADAPTIVE MANAGEMENT
Monitoring the Service’s performance while implementing this plan will help ensure its success.
Monitoring and evaluating allow the Service, other government agencies, the public, and partners to
measure and progress. The Service will monitor, evaluate, and determine whether or not progress is
being made towards achieving the refuge’s purposes, vision, and goals. Monitoring will address
habitat or population objectives and the effects of management activities. Through adaptive
management, evaluation of monitoring and research results may indicate the need to modify refuge
objectives or strategies.
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The Service will review this plan annually to decide if it requires any revisions. The plan will be
modified, along with associated management activities, whenever this review or other monitoring and
evaluating determine that changes are needed to achieve planning unit purposes, vision, and goals.
The Service will revise this plan when significant new information becomes available, or when there
are changes in ecological conditions. At a minimum, plan revision will occur every 15 years. All plan
revisions will follow the procedures outlined in current policy and will require compliance with the
National Environmental Policy Act. The Service will continue to encourage public involvement
regarding management of this refuge.
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VI. Consultation and Coordination
INTRODUCTION
The Crocodile Lake National Wildlife Refuge comprehensive conservation planning process involved
a wide variety of participants, including federal, state, and university researchers; private non-profit
groups; friends of the refuge; and local residents. The diversity and input of participants helped guide
development of the plan and this environmental assessment. A core planning team led the planning
process, and a biological review team helped develop habitat and wildlife needs.
CORE PLANNING TEAM
The core planning team involved staff from Crocodile Lake Refuge, National Key Deer Refuge, and
the Florida Fish and Wildlife Conservation Commission. This team was the primary decision-making
team for this plan. Key tasks of this group involved defining and refining the vision; identifying,
reviewing, and filtering the issues; defining the goals; outlining the alternatives; and providing a reality
check. The team members included:
• Phil Frank, Ph.D., Project Leader, National Key Deer Refuge
• Steve Klett, Refuge Manager, Crocodile Lake National Wildlife Refuge
• Van Fischer, Natural Resource Planner, National Key Deer Refuge
• Randy Grau, Manager, Florida Fish and Wildlife Conservation Commission, Florida Keys
Wildlife and Environmental Areas
BIOLOGICAL REVIEW TEAM
The biological review team consisted of Service and state employees and invited research experts.
The team provided recommendations for management actions based on the most current knowledge
of refuge resources. Members of the biological review team included:
• Chuck Hunter, Biologist, Fish and Wildlife Service, Region 4
• Dean Demarest, Migratory Birds and State Programs, Fish and Wildlife Service, Region 4
• Laura Brandt, Biologist, A.R.M. Loxahatchee National Wildlife Refuge
• Britta Muiznieks, Biologist, Ecological Services, Fish and Wildlife Service
• Ken Meyer, Ph.D., Researcher, Avian Research and Conservation Institute
• Phil Frank, Ph.D., Project Leader, National Key Deer Refuge
• Steve Klett, Refuge Manager, Crocodile Lake National Wildlife Refuge
• Van Fischer, Natural Resource Planner, National Key Deer Refuge
• Randy Grau, Manager, Florida Fish and Wildlife Conservation Commission, Florida Keys
Wildlife and Environmental Areas
• Tom Wilmers, Biologist, National Key Deer Refuge
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SECTION B. APPENDICES
I. Glossary
Adaptive Management A process in which projects are implemented within a framework
of scientifically driven experiments to test predictions and
assumptions outlined within the comprehensive conservation
plan. The analysis of the outcome of project implementation
helps managers determine whether current management should
continue as is or whether it they should modify it to achieve
desired conditions.
Alternative Alternatives are different means of accomplishing refuge
purposes, goals, and objectives and contributing to the National
Wildlife Refuge System. An alternative is a reasonable way to
fix the identified problem or satisfy the stated need.
Approved Acquisition Boundary A project boundary that the Director of the Fish and Wildlife
Service approves upon completion of the detailed planning and
environmental compliance process.
Biological Diversity The variety of life and its processes, including the variety of
living organisms, the genetic differences among them, and the
communities and ecosystems in which they occur. The National
Wildlife Refuge System focus is on indigenous species, biotic
communities, and ecological processes.
Biological Integrity The biotic composition, structure, and functioning at genetic,
organism, and community levels comparable with historic
conditions, including the natural biological processes that shape
genomes, organisms, and communities.
Canopy A layer of foliage; generally, the upper-most layer in a forest
stand. It can refer to mid- or under-story vegetation in multi-layered
stands. Canopy closure is an estimate of the amount of
overhead tree cover (also canopy cover).
Categorical Exclusion A category of actions that do not individually or
cumulatively have a significant effect on the human
environment and have been found to have no such effect in
procedures adopted by a federal agency pursuant to the
National Environmental Policy Act of 1969.
CFR Code of Federal Regulations.
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Compatible Use A wildlife-dependent recreational use or any other use of a
refuge that, in the sound professional judgment of the Refuge
Manager, will not materially interfere with, or detract from, the
fulfillment of the mission or the purposes of the refuge. A
compatibility determination supports the selection of
compatible uses and identifies stipulations or limits necessary
to ensure compatibility.
Comprehensive Conservation Plan A document that describes the desired future conditions of the
refuge; provides long-range guidance and management
direction for the Refuge Manager to accomplish the purposes,
goals, and objectives of the refuge; and contributes to the
mission of the National Wildlife Refuge System and meet
relevant mandates.
Conservation Easement A legal document that provides specific land-use rights to
a secondary party. A perpetual conservation easement
usually grants conservation and ma