Marin Islands National Wildlife Refuge Draft Comprehensive Conservation Plan and Environmental Assessment

              Marin Islands
National Wildlife Refuge
Draft Comprehensive Conservation Plan
and Environmental Assessment
U.S. Fish & Wildlife Service
Comprehensive Conservation Plans provide long term guidance for management decisions and set forth
goals, objectives, and strategies needed to accomplish refuge purposes and identify the Service’s best
estimate of future needs. These plans detail program planning levels that are substantially above current
budget allocations and, as such, are primarily for Service strategic planning and program prioritization
purposes. The plans do not constitute a commitment for staffing increases, operational and maintenance
increases, or funding for future land acquisition.
Cover photo USFWS
Marin Islands National Wildlife Refuge and
State of California Ecological Reserve
Draft Comprehensive Conservation Plan
Prepared By
U.S. Fish and Wildlife Service
San Francisco Bay National Wildlife Refuge Complex
P.O. Box 524
Newark, CA 94560
Approved: ____________________________________________ Date: _____________________________
California Nevada Operations Manager
Implementation of this Comprehensive Conservation Plan and alternative management actions/programs have been
assessed consistent with the requirements of the National Environmental Policy Act (42 USC 4321 et seq.).
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Table of Contents
Chapter 1. Introduction and Background .............................................................................. 1
Introduction.............................................................................................................................. 1
Environmental Assessment................................................................................................ 1
Need for this CCP .................................................................................................................... 2
Legal and Policy Guidance ...................................................................................................... 2
The U.S. Fish and Wildlife Service and the National Wildlife Refuge System................. 4
U.S. Fish and Wildlife Service ........................................................................................... 4
The National Wildlife Refuge System............................................................................... 4
National Wildlife Refuge System Mission and Goals .................................................... 5
San Francisco Bay National Wildlife Refuge Complex ....................................................... 5
The Marin Islands National Wildlife Refuge and State of California Ecological Reserve
.................................................................................................................................................... 6
Introduction......................................................................................................................... 6
Refuge Setting....................................................................................................................... 8
Refuge History...................................................................................................................... 9
Timeline of the Refuge’s History...................................................................................... 12
Refuge Establishment and Explanation of Refuge Purposes ...................................... 13
Current Management ........................................................................................................ 14
Land Ownership................................................................................................................. 17
Existing Partnerships for Management......................................................................... 17
Relationship to Ecosystem Management Goals ............................................................ 18
Adaptive Management ...................................................................................................... 18
Chapter 2. The Comprehensive Conservation Planning Process.................................... 19
The Planning Process: How this CCP was Developed....................................................... 19
The Planning Core Team.................................................................................................. 20
The Planning Expanded Team ........................................................................................ 21
Public Involvement in Planning...................................................................................... 21
Development of Refuge Vision.............................................................................................. 23
Development of Refuge Goals, Objectives and Strategies................................................. 23
Development of Alternatives................................................................................................. 24
Plan Implementation.............................................................................................................. 24
Chapter 3. Refuge and Resource Description...................................................................... 25
Physical Resources................................................................................................................. 25
Climate................................................................................................................................ 25
Surface Hydrology ............................................................................................................. 26
Water Supply ...................................................................................................................... 26
Water Quality ..................................................................................................................... 27
Topography ......................................................................................................................... 27
Geology................................................................................................................................ 27
Soils..................................................................................................................................... 28
Wilderness Inventory ........................................................................................................ 29
Air Quality......................................................................................................................... 29
Hazardous Materials and Contaminants ...................................................................... 29
Biological Resources at the Refuge...................................................................................... 30
Vegetation........................................................................................................................... 30
East Marin Island ............................................................................................................. 30
West Marin Island............................................................................................................. 36
Wildlife ............................................................................................................................... 37
Federally and State Listed Species at the Refuge .......................................................... 43
Cultural Resources ................................................................................................................. 43
Social and Economic Environment....................................................................................... 44
Land Use ............................................................................................................................. 44
Traffic and Public Access.................................................................................................. 45
Recreation ........................................................................................................................... 45
Environmental Justice...................................................................................................... 47
Ethnic and Income Characteristics ................................................................................. 48
Chapter 4. Challenges and Opportunities.............................................................................. 48
Challenges ............................................................................................................................... 48
Chapter 5. Management Direction......................................................................................... 49
Refuge Vision Statement ....................................................................................................... 50
Refuge Management Goals.................................................................................................... 50
Refuge Objectives and Management Strategies................................................................. 51
Chapter 6. Plan Implementation ............................................................................................ 61
Funding and Personnel.......................................................................................................... 61
Step-Down Management Plans............................................................................................. 63
Compatibility Determination ................................................................................................ 63
Compliance Requirements .................................................................................................... 64
Partnership Opportunities..................................................................................................... 64
Monitoring and Evaluation.................................................................................................... 64
Adaptive Management ........................................................................................................... 65
Plan Amendment and Revision ............................................................................................. 65
Tables
Table 1. Native and Non-Native Vegetation Types on East Marin Island.......................... 30
Table 2. 2004 Egret and Heron Colony Survey ....................................................................... 39
Table 3. Employment characteristics of the San Francisco Metropolitan Statistical Area
(2002) .............................................................................................................................. 47
Table 4. Marin County Ethnicity ............................................................................................... 48
Table 5. Management Goals........................................................................................................ 57
Table 6. Staffing Plan and Needs............................................................................................... 62
Table 7. Budget proposal for Marin Islands NWR Comprehensive Conservation Plan ... 62
Table 8. Monitoring Methods...................................................................................................... 64
Figures
Figure 1. Location Map………………………………………………………………………. ..7
Figure 2. Refuge Map………………………………………………………………………… 10
Figure 3. Non-Native Vegetation Removed on East Marin Islands……………………… 16
Figure 4. The CCP Process………………………………………………………................... 20
Figure 5. East Marin Island- Lagoon Detail……………………………………………….. 35
Figure 6. Location of Structures…………………………………………………………….. 46
Figure 7. Map of Management Actions……………………………………………………... 60
Appendices
A. References
B. Glossary of Terms and Acronyms
C. Refuge Plant Species List
D. Refuge Bird Species List
E. Fish Species List
F. Refuge Species of Concern
G. Environmental Assessment
H. Recreational Sport Fishing Plan for the Marin Islands NWR
I. Marin Islands NWR Wildland Fire Management Plan
J. Marin Islands NWR and SER Vegetation Management Plan
K. Non-native Plant Management Table
L. Native Plant Management Table
M. Compatibility Determination for Research and Monitoring
N. Compatibility Determination for Wildlife Observation and Photography
O. Compatibility Determination for Environmental Education and Interpretive
Staff-led Tours
P. Compatibility Determination for Sport Fishing
Q. Wilderness Inventory
R. Memorandum of Understanding between USFWS, CDFG, California State
Lands Commission, Marin County Open Space District, and the Trust for
Public Land
S. Planning Team Members and Persons Responsible for Preparing this
Document
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Draft Comprehensive Conservation Plan 1
Chapter 1. Introduction and Background
Introduction
The Marin Islands are a joint National Wildlife Refuge and State Ecological Reserve
(Refuge) located in San Francisco Bay in northern California. The Refuge is composed of
two small islands and adjacent tidelands set in the San Rafael Bay portion of the San
Francisco Bay estuary. Day-to-day management is provided by the U.S. Fish and
Wildlife Service (Service) under a memorandum of understanding with the California
Department of Fish and Game. The Refuge is unique because it provides increasingly
limited wildlife habitat in the heart of the heavily populated San Francisco Bay area.
The Service prepared this Draft Comprehensive Conservation Plan (CCP) to guide
wildlife and other natural resource management with consideration for compatible public
use on the Refuge for the lifetime of this 15-year plan. The CCP is flexible; it will be
revised periodically to ensure that its goals, objectives, implementation strategies, and
timetables remain valid and appropriate. Major revisions will require public involvement
and appropriate National Environmental Policy Act (NEPA) documentation. The
Service’s management planning process for National Wildlife Refuges (NWRs) involves
two phases: 1) the development of a broad CCP that articulates a vision and specific goals
for a refuge; and 2) the formulation of more detailed “step-down” management plans that
enable the implementation of the CCP’s vision. The purposes of this CCP are to:
• Provide a clear statement of direction for the management of the Refuge during
the lifetime of this plan;
• Provide long-term continuity in Refuge management;
• Communicate the Service’s management priorities for the Marin Islands Refuge to
its neighbors and the public;
• Provide an opportunity for the public to help shape the future management of the
Marin Islands Refuge;
• Ensure that management programs on the Marin Islands Refuge are consistent
with the legal and policy mandates for the National Wildlife Refuge System
(Refuge System) and the purpose of the Refuge as stated in establishing
documentation;
• Ensure that the management of the Marin Islands Refuge is, to the extent
practicable, consistent with Federal, State, and local plans; and
• Provide a basis for budget requests to support the Marin Islands Refuge’s needs
for staffing, operations, maintenance, and capital improvements.
Environmental Assessment
This document also includes an environmental assessment (EA) as required under NEPA
(42 USC 4321), the basic national policy for consideration of environmental values in
federal decision making. This document was prepared as a concurrent CCP/EA because
2 Draft Comprehensive Conservation Plan
regulations of the President’s Council on Environmental Quality require the Service to
integrate the NEPA review and compliance process with CCP development and
implementation as early as possible, in order to ensure a systematic and interdisciplinary
approach. The purpose of the EA is to evaluate the environmental effects of the CCP on
the quality of the human environment, as required by NEPA. The EA includes:
• Description of the alternatives to the proposed CCP;
• Identification and analysis of the environmental effects of the proposed
management program and the management alternatives; and
• Involvement of affected State and Federal agencies, Native American Tribes, and
members of the public in the CCP process.
The CCP is also accompanied by the following step-down management plans:
• Recreational Sport Fishing Plan and Environmental Assessment for the Marin
Islands NWR (Appendix H); and
• Marin Islands NWR Wildland Fire Management Plan (Appendix I)
Need for this CCP
No formal management plan currently exists for this Refuge; therefore, a CCP is needed
to provide guidance in conducting general refuge operations, wildlife and habitat
management, cultural resource protection, environmental education and wildlife
observation. The National Wildlife Refuge System Improvement Act of 1997 (16 USC
668dd-668ee) (1997 Improvement Act) requires that all refuges be managed in accordance
with an approved CCP by 2012. Under this Act, the refuges are to be consistently
directed and managed to fulfill the Refuge System Mission as well as the specific
purpose(s) for which the refuge was established.
The planning process is an additional directive for refuge managers to follow while
achieving the specific refuge purpose(s) and Refuge System mission. It provides for the
consideration and protection of the broad spectrum of fish, wildlife, and habitat resources
found on refuges and associated ecosystems. Further, it provides refuge managers with
an evaluation process to analyze their refuge and recommend the best management
direction to prevent degradation of environmental conditions and restore lost or severely
degraded portions of the refuge, when such restoration is appropriate and in concert with
refuge purposes and Refuge System mission. When evaluating the appropriate
management direction for refuges, refuge managers will use sound professional judgment
to determine their refuges’ contribution to biological integrity, diversity, and
environmental health at multiple landscape scales. Moreover, the 1997 Improvement Act
requires effective coordination with other Federal agencies, state fish and wildlife or
conservation agencies, and local stakeholders.
Legal and Policy Guidance
National Wildlife Refuges are guided by the mission and goals of the Refuge System,
Draft Comprehensive Conservation Plan 3
purposes of the Refuge, Service policy, laws, and international treaties. Relevant
guidance includes the Refuge Recreation Act of 1962, the National Wildlife Refuge
System Administration Act of 1966, as amended by the 1997 Improvement Act, and
selected portions of the Code of Federal Regulations and Fish and Wildlife Service
Manual. The Refuge Recreation Act of 1962, as amended, authorized the Secretary of the
Interior to administer refuges, hatcheries, and other conservation areas for recreational
use when such uses do not interfere with the area’s primary purpose.
The 1997 Improvement Act:
• Identified a new mission statement for the Refuge System;
• Established six priority public uses (hunting, fishing, wildlife observation and
photography, environmental education and interpretation);
• Emphasized conservation and enhancement of the quality and diversity of fish and
wildlife habitat;
• Stressed the importance of partnerships with Federal and State agencies, Tribes, non-governmental
organizations, industry, and the general public;
• Mandated public involvement in decisions on the acquisition and management of
refuges; and
• Required, prior to acquisition of new refuge lands, identification of existing compatible
wildlife-dependent uses that would be permitted to continue on an interim basis
pending completion of comprehensive conservation planning.
The 1997 Improvement Act establishes the responsibilities of the Secretary of the Interior
for managing and protecting the Refuge System; requires a CCP for each refuge by the
year 2012; and provides guidelines and directives for the administration and management
of all areas in the Refuge System, including wildlife refuges, areas for the protection and
conservation of fish and wildlife threatened with extinction, wildlife ranges, game ranges,
wildlife management areas, or waterfowl production areas.
The 1997 Improvement Act also establishes a formal process for determining
compatibility of uses. A compatibility determination is required for a wildlife-dependent
recreational use or any other public use of a refuge. A compatible use is one which, in the
sound professional judgment of the refuge manager, will not materially interfere with or
detract from the fulfillment of the Refuge System Mission or refuge purpose(s). The
Service strives to provide wildlife-dependent public uses when compatible. If financial
resources are not available to design, operate, and maintain a priority use, the refuge
manager will take reasonable steps to obtain outside assistance from the State and other
conservation interests.
This draft CCP contains several draft compatibility determinations for proposed uses on
the Refuge. These documents are located in Appendix M-P. These will be finalized along
with the CCP.
4 Draft Comprehensive Conservation Plan
While the Refuge System mission and the purposes by which the Refuges are established
provide the foundation for management, National Wildlife Refuges are also governed by
other Federal laws, Executive Orders (EO), treaties, interstate compacts, regulations,
policies and conservation initiatives pertaining to the conservation and protection of
natural and cultural resources. Some of these include: Floodplain Management (EO
11988), Intergovernmental Review of Federal Programs (EO 12372), National
Environmental Policy Act of 1969, Protection of Historical Archaeological, and Scientific
Properties (EO 11593), Protection of Wetlands (EO 11990), Environmental Justice in
Minority Populations and Low-Income Populations (EO 12898), Endangered Species Act
of 1973, as amended, Emergency Wetlands Resources Act of 1986, Fish and Wildlife Act
of 1956, National Historic Preservation Act of 1966, as amended, Coastal Zone
Management Act of 1972, as amended, Responsibilities of Federal Agencies to Protect
Migratory Birds (EO 13186), Migratory Bird Treaty Act of 1918, the Fish and Wildlife
Conservation Act of 1980, as amended, Neotropical Migratory Bird Conservation Act of
2000, North American Waterfowl Management Plan, U.S. Shorebird Conservation Plan,
Riparian Bird Conservation Plan (Riparian Habitat Joint Venture / California Partners in
Flight), North American Bird Conservation Initiative, and the North American Waterbird
Conservation Plan.
The U.S. Fish and Wildlife Service and the National Wildlife Refuge System
U.S. Fish and Wildlife Service
The Service is the primary Federal agency responsible for conserving, protecting and
enhancing the Nation’s fish and wildlife populations and their habitats for the continuing
benefit of the American people. Although the Service shares this responsibility with other
Federal, State, Tribal, local, and private entities, the Service has specific responsibilities
for migratory birds, threatened and endangered species, inter-jurisdictional fish, and
certain marine mammals. These are referred to as Federal trust species. The Service
also manages the National Wildlife Refuge System and National Fish Hatcheries;
enforces Federal wildlife laws and international treaties related to importing and
exporting wildlife; assists State fish and wildlife programs; and helps other countries
develop wildlife conservation programs. The Service has similar responsibilities for the
lands and waters it administers to support the conservation and enhancement of fish and
wildlife.
The National Wildlife Refuge System
The National Wildlife Refuge System is the world’s largest collection of lands specifically
managed for fish and wildlife conservation. Unlike other Federal lands that are managed
under a multiple-use mandate (e.g., National Forests and lands administered by the U.S.
Bureau of Land Management), the Refuge System is managed primarily for the benefit of
fish, wildlife, and plant resources and their habitats. The Refuge System consists of over
545 units that provide nearly 95 million acres of important habitat for native plants and
many species of mammals, birds, fish and threatened and endangered species.
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National Wildlife Refuge System Mission and Goals
The mission of the National Wildlife 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” (1997
Improvement Act).
The goals of the National Wildlife Refuge System are to:
a. Fulfill our statutory duty to achieve refuge purposes(s) and further the System
mission;
b. Conserve, restore where appropriate, and enhance all species of fish, wildlife, and
plants that are endangered or threatened with becoming endangered;
c. Perpetuate migratory bird, interjurisdictional fish, and marine mammal
populations;
d. Conserve a diversity of fish, wildlife, and plants;
e. Conserve and restore, where appropriate, representative ecosystem of the United
States, including the ecological processes characteristic of those systems; and
f. Foster understanding and instill appreciation of fish, wildlife, and plants, and
their conservation, by providing the public with safe, high-quality, and compatible
wildlife-dependent public use. Such use includes hunting, fishing, wildlife
observation and photography, and environmental education and interpretation.
San Francisco Bay National Wildlife Refuge Complex
The San Francisco Bay area has had a significant human presence stretching back
thousands of years. A number of Native American tribes have inhabited the area,
including the earliest residents, the Ohlone. Later, Spanish settlers immigrated to the
area in the late 1700s. The years following the California gold rush in 1849 caused
explosive growth and development that placed greater demands on the sensitive lands
surrounding the Bay. For example, the salt industry converted tens of thousands of acres
of salt marsh into commercial salt ponds.
Conversion of wetlands to support development continued well into the 20th century and
today, nearly 85 percent of the Bay’s original marshes and shorelines have been altered.
With the support of citizens and public officials, seven refuges have been created in the
San Francisco Bay Area: Farallon NWR (1909), Salinas River NWR (1973), San Pablo
Bay NWR (1974), San Francisco Bay NWR (1974), Ellicott Slough NWR (1975), Antioch
Dunes NWR (1980), and Marin Islands NWR (1992). These seven refuges, spanning
Monterey Bay to the San Francisco Bay Delta, were combined to create the Refuge
Complex. These refuges provide a variety of critical nesting habitat, traditional grounds,
and resting areas for Pacific shorebirds, waterfowl, species of concern, and endangered
species. Unlike other refuges located in remote locations, each of the seven refuges
shares the task of pursuing wildlife conservation objectives while addressing human needs
6 Draft Comprehensive Conservation Plan
in a highly urbanized environment. Specifically, Congressman Don Edwards worked with
Congress to approve the purchase of lands for the San Francisco Bay National Wildlife
Refuge, which was officially established in 1974 (Public Law 92-330). This Refuge was
officially renamed Don Edwards San Francisco Bay NWR in 1995 and serve as the
Complex’s headquarters.
The Marin Islands National Wildlife Refuge and State of California Ecological
Reserve
Introduction
The Marin Islands Refuge was established as the 479th National Wildlife Refuge and
added to the San Francisco Bay NWR Complex in April of 1992. The Refuge was
established to provide wintering habitat for migratory birds and nesting habitat for
waterbirds. It was established as a joint NWR and State Ecological Reserve (SER) with
day-to-day management provided by the Service under a memorandum of understanding
with the California Department Fish and Game. The Refuge is located in the San Rafael
Bay, within the city limits of San Rafael, Marin County, California (See Figure 1). It
encompasses 339.29 acres of submerged tidelands and two islands. East Marin Island is
approximately 10.28 acres and West Marin Island is approximately 2.8 acres. West Marin
Island is home to one of the largest heron and egret colonies in northern California.
Figure 1. Location Map
Draft Comprehensive Conservation Plan 7
Refuge Setting
The Refuge’s two islands (See Figure 2) and surrounding tideland are located in San
Rafael Bay near the city of San Rafael, which is the closest mainland location. The
Refuge is also within the coastal California North American Bird Conservation Region.
The area surrounding the Refuge is heavily urbanized and the nearby waters attract
recreational and commercial boating. The islands of the Refuge are officially closed to the
public, though occasional illegal trespassing occurs by some recreational boaters.
East Marin Island
USFWS
There is no available historic data on the specific natural conditions of the Marin Islands.
In pre-settlement times, the Refuge habitat was thought to primarily consist of coast live
oak woodlands, coastal sage scrub, and coastal grasslands (Baye 2005). The islands were
isolated by a rise in sea level during the late Holocene period, approximately 3000 years
B.P. (Atwater et al. 1979). Given this separation from the mainland, the historic flora on
Marin Islands represents a limited sample of the common widespread species of the flora
found along northeastern San Francisco Bay. The soil on Marin Islands is categorized as
the Tocaloma-McMullin complex of gravelly loams, loams, and Saurin clay loams.
However, the soils on East Marin Island have been modified by human activities,
including the addition of a high content of fine shell fragments (USDA 1979, Kroll 1991).
8 Draft Comprehensive Conservation Plan
The Refuge vegetation currently consists of mixed evergreen forest, coastal prairie,
coastal salt marsh, and northern coastal scrub. The majority of Refuge land is submerged
tideland. Of the two islands, the larger East Marin Island harbors many non-native and
invasive plant species due, in part, to earlier planting by previous owners of the island.
Previous owners built two residential structures, a pumphouse and water storage tank on
East Marin Island. West Marin Island is surrounded by cliffs, providing little opportunity
for access. Limited by accessibility, there is no visible human disturbance on this island
today, except for some signage. While there are no known endangered species or
mammals that breed on the Refuge, California brown pelicans were observed roosting at
West Marin Island during low tide and foraged in the surrounding waters continuously
throughout the summer season in 2005 (pers. comm., Block). The islands, however,
provide nesting habitat to one of the largest heron and egret colonies in northern
California.
Refuge History
The earliest available written records indicate that Spain claimed ownership of California
beginning in 1542 and therefore, ownership of the Marin Islands. However, there is
significant historical knowledge and evidence that Native Americans in Marin County
occupied the islands at one time. Mexico’s independence from Spain in 1822 resulted in
the transfer of ownership of the islands to Mexico. Chief Marin of the Hukueko tribe, for
which the area and islands were named, used the islands as a hideout to elude Mexican
soldiers in 1824 (Teather 1986). The islands were ceded to the United States in 1846 as a
result of the Mexican-American War.
West Marin Island
USFWS
Draft Comprehensive Conservation Plan 9
Figure 2. Refuge Map
10 Draft Comprehensive Conservation Plan
Draft Comprehensive Conservation Plan 11
The islands became property of the United States when California was admitted into
statehood in 1850. The history of the property’s ownership is unclear from 1850 to the
late 1920s. The Federal government likely retained ownership of the property until about
1929, but research indicates it may have intermittently changed hands among an unknown
number of owners until that time. The last private owner was the Harbor Tug and Barge
Company, a subsidiary of Crowley Maritime Corporation, which ran a local tugboat
company. Shipping magnate Thomas Crowley charged his brother with the duty of
purchasing the islands around 1929 at a government auction for $45,000. The purchase
was envisioned as an investment; Crowley thought the island would be naturally used as
footings for the Richmond Bridge, which was under construction at that time (Peabody
2004). However, the islands were never used in the construction of the Richmond Bridge,
but did serve as a retreat for the Crowley family. An arc and pilot house sat on pilings on
the shore of East Marin Island, serving as temporary residences for the family. While the
Crowley family used the island primarily as a day retreat, two houses were eventually
built on the island. The main house was constructed around 1945-1946 by architect, Mario
Corbett. The second smaller guest house was constructed 20 years later by architect
Clarence Mayhew. Rocks from the island’s beach were used in the foundation of the main
house (Peabody 2004). Beach rocks were also used to build the San Quentin prison
located in Marin County, California (Peabody 2004).
West Marin Island attracted fewer inhabitants than East Marin Island. After World War
II, the Sea Scouts, a youth seamanship program, used West Marin Island as a
campground and recreational area (pers. comm., French). However, by the late 1950s
through early 1960s, use of West Marin Island slowed or stopped in favor of other islands
offering facilities. For the most part, West Marin Island was untouched while privately
owned by the Crowley family. The islands were marketed in the 1980s as a $4.5 million
private retreat, but there was no interest (Thurman 1990). In the 1980s, a small flock of
Barbary sheep (Ammotragus lervia) was introduced to East Marin Island to reduce fire
hazard and control vegetation (Schoenherr 1999).
During the period that the Harbor Tug and Barge Company sought to sell the Marin
Islands, local citizens were concerned with the potential conversion of the Marin Islands
from a single-family retreat to high intensity recreation or development. The Friends of
the Marin Islands group formed to successfully lobby and raise funds to protect the
valuable natural resources of the islands. The Friends and the California Coastal
Conservancy purchased an option to buy the islands and surrounding tidelands. With the
expiration of that option, the Trust for Public Land later purchased another option to buy
the islands. Numerous agencies, organizations and citizens participated in the purchase
of this area to establish a National Wildlife Refuge and State Ecological Reserve
including:
• U.S. Fish and Wildlife Service
• Marin County Open Space District
12 Draft Comprehensive Conservation Plan
• California State Lands Commission
• Wildlife Conservation Board
• California Department of Fish and Game
• The Richard and Rhoda Goldman Fund
• Crowley Maritime Corporation
• Friends of Marin Islands
• Marin Audubon Society
• Golden Gate Audubon Society
• Thomas B. Crowley
• Constance Crowley Bowles
• Richard D. Spight
• GAP Foundation
• Dean Witter Foundation
• Hundreds of individuals
Timeline of the Refuge’s History
Pre 1820
The Miwok Indians inhabited the Marin Islands. Cultural resources on the Refuge
indicate many years of Miwok use.
Approximately 1820
The Mexican Government seized the islands from the Miwoks and held the claim to the
islands until the end of the Mexican-American War in 1846.
1848
The Marin Islands were officially transferred to the United States with the signing of the
Treaty of Hidalgo in 1848.
1929
The Marin Islands are purchased by shipping magnate Tom Crowley Sr.
1945-46
Thomas Crowley Sr. constructs main house on East Marin Island for use as a retreat
Between 1965 and 1970
Thomas Crowley Sr. builds guest house on East Marin Island.
1983
Crowley Maritime Corporation puts the Marin Islands up for sale for $4.5 million.
April 16, 1992
Purchase of the Marin Islands complete for $3 million from public and private sources.
Draft Comprehensive Conservation Plan 13
September 19, 1992
Senator Barbara Boxer designated this day Marin Islands National Wildlife Refuge Day.
Refuge Establishment and Explanation of Refuge Purposes
Lands within the Refuge System are acquired and managed under a variety of legislative
acts and administrative orders and authorities. The official purpose or purposes for a
refuge are specified in or derived from the law, proclamation, executive order, agreement,
public land order, funding source, donation document, or administrative memorandum
establishing, authorizing, or expanding a refuge, refuge unit, or refuge subunit. The
purpose of a refuge is defined when it is established or may be modified when new land is
added to an existing refuge. When an addition to a refuge is acquired under an authority
different from the authority used to establish the original refuge, the addition takes on the
purposes of the original refuge, but the original refuge does not take on the purposes of
the addition. Refuge managers must consider all of the purposes. However, the purposes
dealing with the conservation, management, and restoration of fish, wildlife and plants,
and their habitats, takes precedent over other purposes in the management and
administration of a refuge.
The 1997 Improvement Act directs the Service to manage each refuge to fulfill the
mission of the Refuge System, as well as the specific purposes for which that refuge was
established. Refuge purposes are the driving force in developing refuge vision
statements, goals, objectives, and strategies in the CCP. Refuge purposes are also critical
to determining the compatibility of all existing and proposed refuge uses.
Marin Islands National Wildlife Refuge was established under the authority of the Fish
and Wildlife Act of 1956 and the Migratory Bird Conservation Act.
According to these authorities, the primary Refuge-wide purposes are:
“...for the development, advancement, management, conservation, and protection
of fish and wildlife resources...” 16 USC 742f (a) (4) and “...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 USC 742f (b) (1) (Fish and Wildlife Act of
1956).
According to the environmental assessment establishing the Refuge, The Marin Islands
was designated to protect an important existing egret and heron rookery on West Marin
Island and to increase colonial nesting bird use on East Marin Island (USFWS 1992).
Interim Refuge Goals at the time Marin Island NWR was established include (from 1996
Interim Goals):
1- To protect the herons and egrets that nest on West Marin Island and to protect
and enhance the nesting, feeding and roosting habitat that supports them.
2- To protect, restore and enhance the unique island ecosystem and adjacent
tidelands for a diversity of fish and wildlife species native to the San Francisco Bay
area.
3- To establish and provide opportunities for wildlife-oriented education and
recreation within the highly urbanized San Francisco Bay area.
Heron and Egret Colony
USFWS
Current Management
The Refuge has no staff or offices on site due to the challenge of accessing the Refuge by
boat, as well as the lack of available electrical and water resources. Management is
conducted by staff who also manages San Pablo Bay NWR and Antioch Dunes NWR from
an office in Petaluma, California. This staff includes a refuge manager, a refuge biologist,
and a refuge maintenance worker. Refuge staff accesses East Marin Island by refuge
watercraft and a dock. Refuge staff rarely access West Marin Island due to its steep
surrounding cliff and the sensitive nature of the wildlife on the island. There is no active
management of the tidal areas of the Refuge property. Law enforcement from the San
Francisco Bay NWR Complex provides some surveillance of the islands, but refuge
management is dependent on law enforcement conducted by the San Rafael Police
Department. The San Rafael Police check the Refuge for trespassers during their vessel
patrols.
Wildlife Monitoring
Annually during the spring and summer season, the heron and egret colony on West
Marin Island is monitored by Audubon Canyon Ranch to determine trends in breeding
populations, reproductive success, health, and any disturbance factors. Audubon Canyon
Ranch is an organization established to protect heronries on the West Coast through
preservation, environmental education and research. Monitoring of the colony began in
14 Draft Comprehensive Conservation Plan
Draft Comprehensive Conservation Plan 15
1979. Specifically, the great blue heron (Ardea herodias), snowy egret (Egretta thula),
great egret (Ardea alba), and black-crowned night heron (Nycticorax nycticorax) are
monitored annually. Other waterfowl are also included in the survey. Monitoring
activities are conducted by boat and from East Marin Island and they do not access West
Marin Island to avoid disturbance. Because the nests are mostly shrouded in the
vegetation, surveys can only monitor a portion of the colony. Recent surveys found that
individuals in the colony may choose another local site for nesting in any given year.
Resident raven (Corvus corax) predation of the heron and egret colony has been detected
during recent years. A single pair of resident ravens includes the Marin Islands as part of
their territory and protects these areas from other potential predators (e.g., red-tailed
hawks, peregrine falcon, and other ravens). The pair nests on East Marin Island. Study
of raven predatory behavior at the Marin Islands occurred in 1999, 2000, and 2005. The
purpose of these studies is to determine the impact of raven predation on the overall
populations and reproductive success of heron and egret colony on West Marin Island.
Invasive Vegetation Control
The past human influence on East Marin Island has introduced and resulted in
infestations of non-native vegetation. West Marin Island has substantially less non-native
vegetation because it was not subjected to disturbance from long-term human activity.
Because the Refuge lacks electricity, non-native control has been limited to hand cutting
or gas-powered chainsaws to remove fennel, acacia, Scotch broom, and young Monterey
Pine. It is not possible to remove invasive plants by prescribed burns, digging or
uprooting vegetation because the island soil is considerably sandy and erosive. Figure 3
indicates areas where vegetation has been removed.
Public Access and Wildlife-Dependent Recreation
Public use activities are not allowed on refuges until determined compatible with a
refuge’s purpose. Such uses include hunting, fishing, wildlife observation, photography,
and environmental education and interpretation. Both islands are closed to unrestricted
access and no public use activities have been assessed because of wildlife protection and
public safety. Signage is posted along the shoreline of both islands noting this restriction.
However, recreational boaters are able to view the islands and wildlife from their
watercraft. Fishing from boats has existed in the area prior to the Refuge’s establishment
and continues today. This CCP contains a draft compatibility determination that formally
assesses this activity. Fishing is prohibited from the islands’ shoreline.
16 Draft Comprehensive Conservation Plan
Land Ownership
Several donors were involved with purchasing the islands and the tidelands (as noted in
the Refuge History section of this document). These islands and tidelands total 339.29
acres and were permanently transferred to the California Department of Fish and Game
(CDFG), the State Lands Commission, and the Service for ownership and management
(See Appendix R). East Marin Island totals 10.28 acres and West Marin Island totals 2.8
acres, leaving 326.21 acres of tidelands. The Service took ownership of the eastern
portion of East Marin Island and approximately 80 acres of tidelands (See Figure 2). The
State Lands Commission took ownership of the remaining tidelands within the approved
refuge boundary. The CDFG owns West Marin Island (2.8 acres) and the western portion
of East Marin Island. Regardless of specific ownership divisions of the area, the entire
area of islands and tidelands is designated as the Marin Islands NWR and as a SER. This
area is managed under Service and State of California mandates. The Service provides
day-to-day management of the entire Marin Islands NWR/SER according to
memorandum of understanding (Appendix R) and under the National Wildlife Refuge
System Administration Act.
Existing Partnerships for Management
The Refuge has benefited from partnerships with several entities and individuals. The
local San Rafael Police Department provides additional law enforcement to support the
Service’s Law Enforcement efforts. The Save The Bay Association conducts a regular
education and plant restoration program on East Marin Island to reestablish native
vegetation to the Refuge. The Friends of San Pablo Bay National Wildlife Refuge are
currently helping to finance the construction of a greenhouse at the San Pablo Bay
Refuge to propagate native plants for habitat restoration activities. The Friends group
has also participated in removal of non-native vegetation on East Marin Island.
Volunteers conducting plant restoration
© Save The Bay
Draft Comprehensive Conservation Plan 17
18 Draft Comprehensive Conservation Plan
Relationship to Ecosystem Management Goals
To the extent possible, a CCP will assist in meeting conservation goals established in
existing national and regional plans, State fish and wildlife conservation plans, and other
landscape-scale plans covering the same watershed or ecosystem in which the Refuge
resides (602 FW 3.3). There are several water and land management plans in place at the
Refuge’s location in the San Francisco Bay watershed in the Central Basin region. The
watershed conveys the waters of the Sacramento and San Joaquin rivers into the Pacific
Ocean. The watershed forms the centerpiece of the United States’ fourth largest
metropolitan region. The freshwater to hypersaline environment also supports a
biologically diverse area.
Watershed planning is directed by the Regional Water Quality Control Board (RWQCB),
but requires the involvement of several agencies, local governments, nonprofit
organizations, and individuals. The RWQCB regulates surface and groundwater sources.
The RWQCB developed a Water Quality Control Plan (Basin Plan) for the watershed that
is the master policy document that contains descriptions of the legal, technical, and
programmatic bases of water quality regulation in the San Francisco Bay region. This
document is reviewed every three years to keep up with the technological, hydrological,
political, and physical changes in the region.
In addition to the Basin Plan, the San Francisco Estuary Project was formed in 1987 as a
vehicle to coordinate Federal, State, and local programs to promote effective management
of the San Francisco Bay-Delta Estuary. The U.S. Environmental Protection Agency and
the State of California are the primary sponsors of the Estuary Project. The Estuary
Project has developed a Comprehensive Conservation and Management Plan (CCMP) to
address five critical concerns of the watershed: decline of biological resources; increased
pollutants; freshwater diversion and altered flow regime; dredging and waterway
modification; and intensified land use. The CCMP strives to maintain, protect, and
enhance the ecological integrity of the Estuary within the given urban context. The
CCMP reviews several program areas of the watershed including: Aquatic Resources,
Wildlife, Wetlands Management, Water Use, Pollution Prevention and Reduction,
Dredging and Waterway Modification, Land Use, Public Involvement and Education, and
Research and Monitoring.
A Marin County Plan was created to guide the direction of development in Marin County.
The Plan considers economic, environmental, and equity elements in the planning process.
The natural environment is one component of the Plan, which takes into consideration the
need and retention of open space in the county. The Marin Islands NWR is designated an
important open space area in this Plan.
Adaptive Management
The Service acknowledges that much remains to be learned about the species, habitats,
and physical processes that occur on the Refuge, and about the ecological interactions
Draft Comprehensive Conservation Plan 19
between species. When faced with uncertainty resulting from complex ecological
interactions or gaps in available data, the most effective approach to resource
management over the long term is an adaptive one. Adaptive management refers to a
management style in which the effectiveness of management actions is monitored and
evaluated on an ongoing basis, and future management is modified as needed, based on
the results of this evaluation or other relevant information that becomes available. The
Service has been practicing adaptive management on the Refuge since 1991 and plans to
continue this practice. Accordingly, the management scenario proposed in this CCP
provides for ongoing adaptive management of the Refuge; its adaptive management
component is described more fully in Chapter 6, Plan Implementation. The CCP may be
amended as necessary at any time under an adaptive management strategy.
Chapter 2. The Comprehensive Conservation Planning Process
This CCP/EA for the Refuge is intended to meet the dual requirements of compliance
with the 1997 Improvement Act and NEPA. The development of this CCP/EA was also
guided by the Refuge Planning Policy outlined in Part 602, Chapters 1, 3, and 4 of the
Service Manual (Fish and Wildlife Service 2000). Service policy, the 1997 Improvement
Act, and NEPA provide specific guidance for the planning process. For example, Service
policy and NEPA require the Service to actively seek public involvement in the
preparation of environmental documents such as EAs. NEPA also requires the Service to
give serious consideration to all reasonable alternatives, including the “no action”
alternative, which represents continuation of current conditions and management
practices. Alternative management scenarios were developed as part of the planning
process and can be found in Appendix G (Environment Assessment).
The Planning Process: How this CCP was Developed
Key steps in the CCP planning process and depicted below and include:
1. Preplanning
2. Identifying issues and developing a vision statement
3. Gathering information
4. Analyzing resource relationships
5. Developing alternatives and assessing environmental effects
6. Identifying a preferred alternative
7. Publishing the draft plan and NEPA document
8. Documenting public comments on the draft plan
9. Preparing the final plan
10. Securing approval of the Regional Director
11. Implementing the plan
Figure 4. The CCP Process
Review and
Revise the
Plan
Public Scoping
& Identify
Issues
Prepare
Draft Plan
Final Plan
Implement
Plan &
Monitor
Vision Statement
& Goals
Develop
Objectives,
Strategies, &
Alternatives
Initiate Study
Pre-Planning
The
CCP
Process
Review and
Revise the
Plan
Public Scoping
& Identify
Issues
Prepare
Draft Plan
Final Plan
Implement
Plan &
Monitor
Vision Statement
& Goals
Develop
Objectives,
Strategies, &
Alternatives
Initiate Study
Public
Pre - Planning
Input
Public
Input
Public
Input
Public
Input
Public
Input
Public
Input
Public
Input
Public
Input
The CCP may be amended as necessary at any time under an adaptive management
strategy. Major revisions if needed will require public involvement and NEPA review.
The planning process for this CCP began in July 2004 with collection of pertinent data
and selection of team members. A core team and expanded team were each formed to
integrate stakeholders into the planning process. Refuge staff identified three primary
areas of focus: wildlife management, habitat management and public access and
education. These focus areas helped shape comments received from the public during the
scoping period into potential objectives for the Refuge.
The Planning Core Team
The planning team responsible for leading the CCP effort included Service biologists,
planners, and public use specialists from the San Francisco Bay NWR Complex and the
20 Draft Comprehensive Conservation Plan
Draft Comprehensive Conservation Plan 21
California/Nevada Refuge Planning Office. Appendix S lists the members of the planning
core team.
The Planning Expanded Team
The expanded team is the advisory forum of the CCP process. Its role is significant
because of the Refuge’s history of networking and partnerships with local, state and
federal agencies, community groups, research institutes, and non-profit organizations
concerned with the Marin Islands. The expanded team is composed of state and federal
congressional officials, local government officials, non-profit organizations, community
groups, and other interested parties. The goal of the expanded team is to provide
comments on the goals and strategies of the plan to help the Service with the decision-making
process.
Public Involvement in Planning
Public involvement is an important and required component of the CCP and NEPA
process. Public scoping meetings allow the Service to provide updated information about
the Refuge System and the Refuge. More importantly, these meetings allow refuge staff
to hear public comments and concerns. Public meetings provide a forum for important
discussion and identify important issues regarding the Refuge and its surrounding area.
The Refuge hosted a public scoping meeting on October 19, 2004. Public comments were
generated from the public scoping meeting and the Federal Register Notice published on
September 22, 2004. Approximately 15 people attended the meeting. A number of
individuals provided comments at the meeting, via email and postal mail. The following
organizations submitted comments: The Wilderness Society, Save The Bay Association
and Audubon Canyon Ranch (ACR). The following paragraphs describe themes of the
comments.
Public Access, including Prohibiting Public Access
Comments regarding public access ranged from prohibiting any access to allowing
unlimited public access with interpretive trails. Comments related to prohibiting access
ranged from barring public access to prohibiting refuge management from accessing the
islands to protect the heron and egret colony and allow natural restoration of the islands.
Comments supporting public access included recommendations to create a water trail for
use by passive recreation, such as kayaking (as suggested by Save The Bay Association).
Another comment recommended that ACR develop a guided tour based on their
knowledge of the heron and egret colony on the Refuge. Primarily, public access was
supported to allow opportunities for bird watching.
Wildlife and Feeding Habitat
A number of recommendations promoted wildlife protection as the main priority for the
Refuge. ACR stressed the need to protect the egret and heron colony, and provide
suitable nesting habitat for the colony on East Marin Island. Several individuals
suggested removing the buildings on East Marin Island in order to deter trespassing and
wildlife disturbance on the Refuge.
ACR and an individual also recommended monitoring predators and their effects on the
colony and if necessary, management of these predators. ACR also recommended
developing a protocol for monitoring and quick removal of non-native predators. Two
individuals recommended studying the impacts of the resident Canada geese population.
Several recommendations were made to protect or acquire nearby feeding areas that
appear to be silting up.
Restore native plants and remove non-native plants
Several individuals and organizations supported the removal of non-native plants and
replacement by native plants. San Francisco’s Save The Bay Association supports
continued public participation in local and community-based opportunities to restore
native vegetation on East Marin Island. Another comment recommended burning brush
collected from non-native plant removal activities. ACR also recommended monitoring
vegetation for changes in structure and recruitment of nest plant species. ACR suggested
removing non-native vegetation on East Marin Island and replacing it with predominant
native vegetation to reflect assemblages found on the northeast side of West Marin
Island. Specific non-native species include eucalyptus and pine which should be replaced
gradually with native oak and buckeye.
Maintain/Restore Lagoon
One comment suggested restoring the lagoon area to its original state. Another comment
suggested preserving the area for use by waterbirds and shorebirds.
Manmade lagoon on East Marin Island
USFWS
22 Draft Comprehensive Conservation Plan
Draft Comprehensive Conservation Plan 23
Local Monitoring
Two individuals suggested the use of community-based patrols, including participation by
the recreational fishing community.
Removal of Houses and Related Infrastructure
There were several recommendations to remove the housing and related structures from
East Marin Island. There were also recommendations to renovate the structures for use
as a caretaker office, visitor center, or research facility.
Public Education and Research Opportunities
One individual recommended educating fishermen, guides and private boaters that
frequently use the area about appropriate boating around the Refuge. Two comments
suggested using the Refuge as a research facility for students.
Boater Traffic Limits
Some recommendations suggested decreasing boater access within the refuge boundary.
One comment recommended putting signs on buoys to alert boaters of the habitat value of
the islands, while another suggested decreasing traffic in the area to encourage the return
of seals and other marine mammals.
Wilderness Area Designation
The Wilderness Society recommended considering wilderness area designation for
Refuge.
Research Sub-tidal and Tidal Resources of the Refuge
A number of individuals and Save The Bay Association suggested inventorying the
submerged areas of the Refuge. They commented that resources, including possible
endangered or threatened species, may occur within refuge boundaries.
Development of Refuge Vision
A vision statement is developed or reviewed for each individual refuge unit as part of the
CCP process. Vision statements are grounded in the unifying mission of the Refuge
System, and describe the desired future conditions of the refuge unit in the long term
(more than 15 years). They are based on the refuge’s specific purposes, the resources
present on the refuge, and any other relevant mandates.
Development of Refuge Goals, Objectives and Strategies
Refuge goals are necessary for outlining the desired future conditions of a refuge in clear
and succinct statements. The Refuge System defines goals as a “descriptive, open-ended,
and often broad statement of desired future conditions that conveys a purpose but does
not define measurable units” (602 FW 1). Objectives and strategies are then developed to
meet those goals. Objectives are defined as a “concise statement of what we want to
achieve, how much we want to achieve, when and where we want to achieve it, and who is
24 Draft Comprehensive Conservation Plan
responsible for the work” (602 FW 1). Strategies are defined as a “specific action, tool,
technique, or combination of actions, tools, and techniques used to meet unit objectives”
(602 FW 1). Well-written goals, objectives and strategies direct work towards achieving
the Refuge’s vision and purpose. Interim refuge goals were developed within the context
of the authorities that established the Refuge, Refuge System mission and goals, the
Service goals and policies, and ecoregion goals. The existing interim refuge goals are
listed in Chapter 1. These goals will be modified through the CCP development process.
The Refuge is within the Service's Central Valley/San Francisco Bay Ecoregion. The goal
identified for all Service activities in this ecoregion is "to restore, conserve, and protect
the ecological systems and biological diversity of the Central Valley/San Francisco Bay
Ecoregion for present and future generations." (Medlin et al. 1996)
In addition, the goals of the Marin Islands NWR support the Service's urban refuge policy
which states that a primary purpose of urban refuges is ..."to foster environmental
awareness and outreach programs to develop an informed and involved citizenry that will
support fish and wildlife conservation." (Smith 1991)
Development of Alternatives
The CCP process includes the development of a range of alternatives that can be
implemented to meet the goals of the Refuge System and the purpose of the Refuge. The
Refuge System defines alternatives as “different sets of objectives and strategies or
means of achieving refuge purposes and goals, helping fulfill the Refuge System mission,
and resolving issues (602 FW 1). The alternatives are developed based on comments from
the scoping period, as well as input from the planning team and other Service staff. The
EA (Appendix G) describes the development of alternatives, assessment of their
environmental effects, and identification of the preferred management alternative
(proposed action).
Plan Implementation
The CCP will be reviewed by refuge staff to coordinate annual work plans and update the
Refuge Operational Needs System database. This database describes the unfunded
budget needs for each refuge and is the basis upon which the Refuge receives funding
increases for operational needs. The plan may also be reviewed during routine
inspections or programmatic evaluations. Results of the reviews may indicate a need to
modify an integral part of the plan implementation, and management activities may be
modified if the desired results are not achieved. If minor changes are required, the level
of public involvement and NEPA documentation will be determined by the refuge
manager. The CCP will be formally revised about every 15 years.
Draft Comprehensive Conservation Plan 25
Chapter 3. Refuge and Resource Description
There is little written information about the historic conditions of the Refuge. Prior to
human cultivation, the islands represented native vegetation communities representative
of the surrounding San Francisco Bay area, as described previously in the Refuge Setting
section of this document. West Marin Island rises 26 meters above the bay waters off the
shoreline of San Rafael. Native grasses, shrubs, and trees provide the necessary sites for
the great egrets, snowy egrets, great blue herons, and black-crowned night herons that
nest on West Marin Island. East Marin Island once served as a vacation retreat for a
prominent family, and now supports a variety of introduced and native vegetation that
provide nesting materials and roosting sites for the water birds that nest on West Marin
Island. Little is known about the remaining portion of the Refuge which is submerged
tidal and sub-tidal environments. There has been no active monitoring or management of
tidal and sub-tidal environments of the Refuge.
Sheltered coves and shallow mudflats support wintering populations of diving ducks and
shorebirds, feeding sites for the fledged herons and egrets, and roosting sites for a variety
of waterbird species including terns, cormorants, gulls, and pelicans. Refuge facilities
include a boat dock and two houses on East Marin Island, which are closed to the public
for safety reasons.
Physical Resources
Climate
The summer climate of the West Coast is dominated by a semi-permanent high pressure
cell, which is high-centered over the northeastern Pacific Ocean. Because this high
pressure cell is quite persistent, storms rarely affect the California coast during the
summer. In winter, the Bay Area experiences periods of storminess and moderate-to-strong
winds and periods of stagnation with very light winds. The San Francisco Bay
Area climate is characterized by moderately wet winters and dry summers. Winter rains
(November through April) account for about 90 percent of the average annual rainfall.
(BAAQMD 2004)
The eastern side of Marin County has warmer weather and less fog, due to its distance
from the outer coast. Nearby San Rafael experiences average maximum winter
temperatures in the high 50s to low 60s, and average maximum summer temperatures in
the high 70s to low 80s. Average minimum temperatures in San Rafael are in the low 40s
in the winter and low 50s in the summer. The prevailing wind directions throughout
Marin County show less variation, and are generally from the Northwest. San Rafael
reports an average rainfall of 95 centimeters per year. Consistent with the Bay Area
Mediterranean climate, 84 percent of the annual rainfall in Marin occurs November
through March.
Surface Hydrology
The Refuge is located in San Rafael Bay, which is in the north part of the larger San
Francisco Bay estuary. San Rafael Bay is a shallow expanse of open water, averaging less
than three meters deep. Massive sedimentation rates after the gold rush (from 1856 to
1887) resulted in the deposit of more than 250 million cubic meters of sediment into the
northern portion of the San Francisco Bay estuary. From 1887 to 1922, sediment
continued to fill this area, which finally held constant from 1922 to 1951. However, from
1951 to 1983, this portion of the estuary has lost sediment at a rate of about one-quarter of
a million meters per year. This sediment loss is a result of reduced peak flows into the
Bay (Jaffe et al. 1983).
A tidally-influenced lagoon is located on the south side of East Marin Island at the base of
a 75-foot cliff. This stagnant brackish pond receives tidal waters during high tides when
wind action allows waves to overtop the island’s beach and for water to enter the lagoon.
The lagoon is not known to support wildlife or endangered species.
Water Supply
Water is not currently required for refuge management; however future plant restoration
projects may require water. In this situation, refuge management expects to bring water
to East Marin Island by boat. The islands were once fed groundwater via a pipeline from
the mainland that provides City of San Rafael water to the island. This pipeline has since
been damaged by boats that traverse over it and is no longer in service. Some non-potable
water is still stored in a 12,500 gallon redwood water tank on East Marin Island.
However, once that water is depleted, the tank will not be refilled.
Water tank on East Marin Island
USFWS
26 Draft Comprehensive Conservation Plan
Draft Comprehensive Conservation Plan 27
Water Quality
Water quality and sediment in San Rafael Bay is impacted by both the salt water of the
Pacific Ocean and freshwater drainage from surrounding watersheds. Surrounded by
urban and industrial areas, water quality in the San Rafael Bay has been affected by a
number of contaminants. In the San Rafael Bay area, trace contaminants including
copper, mercury, selenium, and nickel have exceeded water quality standards. The San
Francisco Estuary Regional Monitoring Program found that 61 percent of its samples
from 1997-2001 contained at least one contaminant at a concentration exceeding its water
quality objective (SFEI 2003). Exceeded contaminants include DDTs, arsenic, chromium,
copper, mercury, and nickel. Pesticide contamination, including such chemicals as DDE,
was most severe in northern areas of the estuary. PCB concentrations were moderate in
San Rafael Bay. The San Francisco Estuary Regional Monitoring Program found that 79
percent of samples collected from 1997-2001 exceeded the PCB water quality objective
(SFEI 2003). The San Rafael Bay area also incurred the highest levels of polycyclic
aromatic hydrocarbons (Bay Institute 2003).
Topography
West Marin Island rises approximately 26 meters above sea level and has a granite base
with steep rocky banks and rolling terrain. East Marin Island is 25 meters high and also
has steep rocky banks along the majority of its perimeter. The surface of the island is
fairly level undulating terrain.
Geology
The Refuge is part of the larger San Francisco Bay watershed and delta. The watershed
was formed by 240 million years of tectonic and erosional forces (Page 1986). The
subduction of the eastward-moving edge of the Pacific plate along with tectonic uplift
along the eastern boundary of the Sierra Nevada range have been the major forces
shaping the large-scale features of this landscape. The lower, coastal mountains to the
west are primarily composed of sedimentary rock, formed by the crumpling and uplift of
marine sediments skimmed off the top of the Pacific Plate during its subduction under the
North American plate. During the millions of years of its evolution, the Central Valley
was alternately flooded by coastal seas, and exposed as a basin surrounded by slopes that
collected and drained the watershed (Page 1986). Alternative layers of coastal marine and
alluvial sediments eventually deposited to depths of 15,240 meters (Page 1986).
Generally, the underlying geological structure of the watershed was formed about two
million years ago, though many topographic features changed dramatically with the
advance and retreat of the great ice sheets of the Pleistocene epoch, which extended from
two million to 15 thousand years before present (Page 1986). During each glacial episode,
sea level dropped several dozen meters, exposing much of the continental shelf and
draining what remained of the shallow inland sea that had filled portions of the Central
Valley. This reduction in sea level, combined with tectonic uplift, caused the major rivers
of the Central Valley to incise deep channels (Page 1986). Their combined outflows
28 Draft Comprehensive Conservation Plan
traversed a deep gorge through the Coast Ranges (today’s Golden Gate), and then flowed
across a coastal plain that extended out to the Farallon Islands.
About 15,000 years ago, a climatic warming trend known as the “Holocene Transgression”
signaled the final retreat of the Sierran glaciers (Page 1986). Rapid melting continued for
about 9,000 years, causing global sea level to rise at a rate of approximately 20mm/yr
(Atwater et al. 1979). The major sedimentary features of the watershed were formed
during this period. River channels deposited large amounts of sediments, building new
channels and floodplains within their entrenched valleys and resulting in the remarkably
flat and uniform floor of the Central Valley (Bay Institute 1998). The rising ocean first
inundated a coastal plain that is today’s continental shelf, and then continued to intrude
inland of the Golden Gate. By 10,000 years before the present, San Francisco Bay had
started to form.
The Refuge is located in a seismically active region. The Rodgers Creek Fault-Hayward
Fault runs directly through the San Rafael Bay area, which has a 27 percent probability of
a 6.7 or greater earthquake before 2032 (USGS 2003). Two other fault lines, San Andreas
and Concord-Green Valley are within 30 miles of the Refuge. The 1989 Loma Prieta
earthquake, with a Richter magnitude of 6.9, was epicentered about 80 miles south of the
Refuge. Based on its location, the Refuge is expected to experience earthquake activity in
the future.
Soils
Marin Islands is made up of soil type 178 Tocaloma-McMullin complex, with 15 to 30
percent slope (Soil Conservation Service 1978). Tocaloma-McMullin is made up of two soil
conditions described as shallow to moderately deep, and as moderately steep to very
steep. These upland soil types are well-drained soils underlain by sandstone and shale.
Tocaloma soils are moderately deep and well-drained. The surface layer is grayish brown
loam, which is soil material that is seven to 27 percent clay particles, 28 to 50 percent silt
particles, and less than 52 percent sand particles. Tocaloma subsoil is light yellowish
brown very gravelly loam underlain by weathered, fractured sandstone. Tocaloma soil
has moderately high permeability, and therefore low water capacity. Runoff is rapid and
the hazard of water erosion is high.
McMullin soils are shallow and well-drained, which makes available water capacity very
low to low. Runoff is rapid, and the hazard of water erosion is high. The surface layer is
grayish brown gravelly loam. McMullin subsoil is light yellowish brown gravelly loam
underlain by hard fractured sandstone. The native vegetation is mainly mixed hardwoods
and brush. Elevation ranges from 15 to 460 meters.
Draft Comprehensive Conservation Plan 29
Wilderness Inventory
As required by Service planning policy, a wilderness inventory (Appendix Q) was
conducted for the Refuge. None of the Refuge’s lands were eligible for wilderness
designation as defined in the Wilderness Act of 1964.
Air Quality
The Refuge is located in California’s San Francisco Bay Area Air Basin (California Air
Resources Board 2002). This area is subject to state and federal air quality standards.
Areas that do not meet the standards are designated as non-attainment areas, and those
that do comply are designated as attainment areas.
The primary types of pollutants regulated by state and federal law include:
• Particulate matter less than 10 microns in diameter (PM10),
• Ozone
• Carbon monoxide (CO)
• Nitrogen dioxide (NO2)
• Sulfur dioxide (SO2), and
• Lead
The San Francisco Bay Area Air Basin is an attainment area for state and federal CO,
NO2, SO2, and lead standards. It is a nonattainment area for state and federal ozone
standards, and State PM10 standards. Attainment reports are unknown for PM10 federal
Standards (BAAQMD 2004). It is unlikely that the Service’s activities would affect ozone
levels. However, refuge management activities that alter the vegetative cover may expose
soil to blowing wind, possibly increasing PM10 emissions.
Air pollution potential is highest on the eastern side of Marin County. This is where the
semi-sheltered valleys and largest population centers are located (BAAQMD 2004).
Hazardous Materials and Contaminants
A Level 1 Survey, Contaminant Survey Checklist, was completed in 1990 for the proposed
Marin Islands NWR by a Service Environmental Contaminant Specialist. The site
inspection reported on-site buildings: Chemical storage, equipment repair, solvents and
an on-site “sterile” or modified water bodies. No further sampling was required. In 1994,
a Level 1 Survey was completed for Tract 10, with nothing to report and no further
sampling was required. Recently, a limited asbestos survey was conducted by Ninyo and
Moore Consultants (Ninyo and Moore 2000). Asbestos containing materials (ACMs) in
good condition were found in both the main and guest houses. A Certified Asbestos
Consultant should be on site for asbestos removal when it occurs. The cost of professional
asbestos removal is included in the total cost of removing the buildings as figured in the
Table 6.
A 2004 engineering survey yielded a low-level PCB leakage from the electrical unit in the
housing structure. The surveyors recommended removal of the entire electrical system in
order to avoid any accidents on the Refuge.
Biological Resources at the Refuge
Vegetation
Vegetation on the Refuge is limited to West and East Marin Islands because the majority
of the Refuge’s acreages are submerged. The current estimated size of native flora for
both islands is approximately 95 species. Most of East Marin Island’s woody vegetation is
dominated by planted non-native trees and shrubs that compete with native vegetation
(Baye 2004). West Marin Island’s lack of sustained human presence has resulted in
persistence of native California buckeye (Aesculus californica), coast live oak (Quercus
agrifolia), and blackberry (Rubus discolor), which have provided breeding habitat for
egrets and herons of the region. No listed rare, threatened, or endangered plants are
known to occur or breed at Marin Islands, although a number of species are considered
rare or uncommon for Marin County (See Appendix F). A description of native and non-native
vegetation types can be found in the following table. A plant list is available in
Appendix C.
Coast live oak bud
USFWS
East Marin Island
The principal native vegetation types of East Marin Island are stands of mature coast live
oak woodland with California buckeye, understory shrubs, and vines of the oak-buckeye
woodland, coastal scrub dominated by California sage, coastal sea-bluff scrub/forb
associations, and coastal grassland/forb associations as shown in Table 1 (Baye 2004). All
native vegetation types found on the Marin Islands are heavily invaded or locally
dominated by naturalized non-native shrubs and grasses that have spread from past
introductions and cultivation.
Table 1. Native and Non-Native Vegetation Types on East Marin Island
Vegetation Patches Description
Mature coast live oak woodland also interspersed with California buckeye; generally
on gently sloping/moist north-aspect slopes,
sheltered from drying winds and full sun, native
30 Draft Comprehensive Conservation Plan
Draft Comprehensive Conservation Plan 31
trees are infrequent and dwarfed on exposed
southern and southwest slopes
Mature non-native blue gum (Eucalyptus globulus)
and Monterey pine (Pinus radiata)
primarily mature stands with few recruitment of
young stands
Extensive shrub layers dominated by introduced
French broom (Genista monspessulanus)
extensive recruitment and quickly invades open
habitat
Shrub to low tree layers dominated by local
horticultural escapes of ornamental non-native
plants
generally limited expansion and low recruitment
Evergreen liana and shrub layers (including ground
layer) dominated by introduced ivy (Hedera helix),
Himalayan blackberry (Rubus discolor), and
periwinkle (Vinca major)
extensive expansion around the coastline and steep
areas
Bulb-dominated grassland occurring under coastal woodland, blue gum and
Monterey pine overstory; also occurring beneath
horticultural tree plantings
Mixed non-native annual and perennial grassland occurring in the understory of coastal woodland,
blue gum and Monterey pine
Blue wildrye (Elymus glaucus) and bulb grassland occurring on sloping terraces beneath horticultural
tree plantings
Coastal scrub dominated by California sage scrub prevalent on coarse-textured unstable soils of south-facing
scarps and landslide slopes exposed to
southwest winds and full sun
Non-native succulent cliff vegetation prickly-pear and iceplant species have spread along
bluffs and the south shore
Mesic coastal bluff scrub similarly exposed to coastal scrub, but occurs mostly
on fractured bedrock with no soil development
Coast Live Oak Woodland
East Marin Island supports relatively mature coast live oak woodland with well-developed
trunks and closed canopy, similar to stands on Angel Island. Mature California buckeye
individuals occur on East Marin Island, but dominate West Marin Island. California bay
(Umbellularia californica) is a minor component of the woodland, occurring in small
clusters of small trees. The live oak woodland is associated with variable native shrub
understory components, and is heavily invaded by non-native ornamental shrubs and
lianas (woody vines). The woodland is minimally invaded by non-native trees, and is
actively recruiting oak seedlings and saplings in the absence of browsing animals. Coast
live oak seedlings show successful recruitment in recent years, but there is no comparable
recruitment seen for California buckeye. (Baye 2004)
Lupinus species (sp.)
© Peter Chan
Understory Shrubs and Vines
Native understory species include poison oak (Toxicodendron diversilobum), snowberry
(Symphoricarpos albus var. laevigatus), oceanspray (Holodiscus discolor), wood rose
(Rosa gymnocarpa), and blue elderberry (Sambucus mexicana). California honeysuckle
(Lonicera hispidula var. vacillans) is a common woody vine clambering in the trees.
Three ferns also inhabit the understory, including California maidenhair (Adiantum
jordanii, uncommon), wood fern (Dryopteris arguta, common), and California polypody
(Polypodium californicum, common). Bee-plant (Scrophularia californica) is limited in
this community, while toyon (Heteromeles arbutifolia) is a common shrub on the island
(Ornduff and Vasey 1995).
Coastal Scrub
Northern coastal scrub is well-developed on East Marin Island, occurring at the tops and
faces of the cliffs along the western, southern, and eastern portions of the island.
However, this vegetation has been degraded by the dominance of blue gum litter and
shade, which facilitates non-native shrub development. California sagebrush (Artemisia
californica), seaside wooly sunflower (Eriophyllum staechadifolium), and bush
monkeyflower (Mimulus aurantiacus) are common components of this community. A
single individual of coyote brush (Baccharis pilularis) was noted in the early 1990s on the
island and is considered rare. Other forbs scattered on the island include yarrow
(Achillea millefolium), California poppy (Eschscholzia californica), cudweed
(Gnaphalium stramineum), and miner’s lettuce (Claytonia perfoliata). The sedge Carex
barbarae forms large, conspicuous groups and Dichondra donelliana occur on the eastern
end of the island (Ornduff and Vasey 1995).
Coastal Grassland
Common native grasses and forbs occur on the plateau of East Marin Island including
needlegrass (Nassella lepida), soap plant (Chlorogalum pomeridianum), snakeroot
(Sanicula crassicaulis), and hedge nettle (Stachys ajugoides var. rigida) (Ornduff and
32 Draft Comprehensive Conservation Plan
Draft Comprehensive Conservation Plan 33
Vasey 1995). Nonnative grasses include Claytonia perfoliata and Polypodium
californicum. Intact stands of native perennial grassland have been well-preserved on
East Marin Island due to recent (more than 10 to 15 years ago) intense sheep grazing
(Baye 2004).
The 2004 vegetation survey indicated a short-term recovery of native grasslands species
diversity. Native perennial grassland elements, including bunchgrass (Nasella spp.), blue
wildrye (Elymus glaucus), creeping wildrye (Leymus triticoides), bentgrass (Agrostis
pallens), bulbs (Tritelia, Chlorogalum, and Zigadenus), appear stable or are increasing in
partially shaded understory grassland of southern island slopes beneath mature non-native
tree plantings (Baye 2004).
Non-native Vegetation
East Marin Island is dominated by introduced, overstory species, including Monterey
pine (Pinus radiata), blue gum (Eucalyptus globulus), and French broom (Genista
monspessulana). The Monterey pine and blue gum stands are predominately mature
with patches of young pines and young blue gums. This suggests that prior maintenance
reduced the recruitment of blue gum and pine, and therefore, it is likely that stand density
would increase without regular maintenance. East Marin Island is also dominated by a
number of non-native legume species such as French broom that are likely to cause
elevated nitrogen in the soil (Baye 2004). French broom is a highly invasive, persistent
nitrogen-fixing shrub. It forms monotypic stands in open vegetation and semi-shaded
woodland, and leaves abundant persistent seed banks that can regenerate juvenile
populations for many years after the adults are removed (Baye 2004). French broom on
the island consists of all age classes, and spreads quickly through open habitat and under
coast live oak canopies. Stands of non-native Acacia spp. also have considerable
recruitment on the island. Fennel is another legume species that has covered landslide
areas on the south bluff. Pride-of-Madiera (Echium candicans, syn. E. fastuosum) is
abundant to co-dominant on the island. Ornamental horticultural plants brought during
previous ownership are located near the residences. These plants have not shown
potential to spread across the island.
Along the shore, stands of invasive ivy (Hedera helix) and periwinkle (Vinca major) have
spread over the north shore slopes near the boat dock. Prickly-pear cacti (Opuntia ficus-carica)
on the southeast wave-cut bluffs of the island have been relatively slow, but
persistent in invading the area. There is one tidally influenced lagoon (approximately 0.4
acres) located on the south side of East Marin Island (See Figure 5). This area is
designated as depauperate Coastal Salt Marsh, with saltgrass (Distichlis spicata), jaumea
(Jaumea carnosa), and pickleweed (Salicornia virginica). Aquatic green alga
(Cladophora sp.) and ditch-grass (Ruppia maritima) are present in this lagoon. Several
Canary Island date palms are located at the highest high tideline separating the lagoon
from the Bay. These palms do not appear to have a high potential to expand and
propagate.
Non-native prickly pear cactus
USFWS
On the cliff faces, live-forever (Dudleya cymosa ssp. Paniculata), wild buckwheat
(Eriogonum nudum), California broom (Lotus scoparius), and sand-spurrey (Spergularia
macrotheca) predominantly occur as scattered individuals. At the base of the southern
cliff, there are large colonies of annual Phacelia distans, with a few plants of perennial
Stephanomeria elata observed on the rocky slopes at the east end of the island. Some
individuals of Arbutus also occur at the plateau. (Ornduff and Vasey 1995). During the
winter, lichen are present on the soil, rocks, and trees, including Flavopunctelia
flaventior, Physcia callosa, Punctelia subrudecta, Rinodina sp., and Xanthoria
polycarpa (Ornduff and Vasey 1995).
California Buckeye
USFWS
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Draft Comprehensive Conservation Plan 35
Generally, the long-term trend for East Marin Island suggests an overall reduction in
abundance and diversity of all native species. Native grasses could decline as the density
of overstory trees expands and the trees produce more vegetation litter. Expanding non-natives
are also a concern, including Bermuda-buttercup, Himalayan blackberry, jubata
grass, and Ehrharta erecta. Currently, the most urgent threat to native plant cover on
East Marin Island is the presence and continued spread of French broom.
Non-native Pride-of-Madiera
USFWS
West Marin Island
West Marin Island’s primary vegetation types consist of coast live oak woodland and
coastal sage scrub. West Marin Island has experienced less human activity than East
Marin Island, resulting in less exposure to non-native vegetation. There is minimal
information about this island because access is restricted due to the sensitivity of the
heron and egret colony. West Marin Island is considered depauperate woodland
dominated with low, spreading buckeyes, and occasional dwarfed coast live oak (Baye
2004). The island is not heavily forested compared to East Marin Island. Western
portions of the island are mixed with coast live oak, toyon, and shrubs of wood rose. The
eastern portion is dominated by larger coast live oak, toyon, and blue elderberry. Several
trees in the eastern area are covered with English ivy. The dominant tree in the central
and northern slopes is the California buckeye, which is a favored nesting site for herons
and egrets. Some coast live oak trees occur in this area, but are dwarfed by the buckeyes
(Ornduff and Vasey 1995). All of the overstory trees are dwarfed in stature relative to
East Marin Island’s individuals.
Northern coastal scrub on the island occurs in two areas. The southern and eastern
margin of the island is dominated by California sagebrush, a few shrubs of bush
monkeyflower, live-forever (Dudleya cymosa), wild buckwheat and the introduced sow
36 Draft Comprehensive Conservation Plan
thistle (Sonchus oleraceus). Northern coastal scrub along the western and northern
margins of the island includes coyote brush and seaside woolly sunflower. Northside cliffs
host the perennial herb bee-plant and California polypody. (Ornduff and Vasey 1995)
Monkeyflower
USFWS
Coastal salt marsh elements occur between the cliffs and cobble beach around the island.
This element includes Frankenia salina, sand-spurrey (Spergularia macrotheca), and
pickleweed. (Ornduff and Vasey 1995)
Vegetation surveys indicate an increasing trend in native and non-native species richness
on both islands of the refuge based on past species richness (plant list) data (Baye 2004).
An increase in the number of identified plant species may be due, in part, to the increased
intensity of plant surveys through time. However, over the long-term it is suspected that
native species richness would be reduced by long-term expansion of invasive, non-native
vegetation (Baye 2004).
Wildlife
One of the most notable features of the Marin Islands is the heron and egret colony on
West Marin Island. The colony occurs primarily on the northeast side of the island and is
active primarily from February through July of each year. The colony has been
monitored in conjunction with other Bay Area colony sites for the past several decades by
state, non-profit research institutes, and individuals. The California Department of Fish
and Game conducted periodic statewide nesting inventories of major ardeid colonies from
1969-1982. Audubon Canyon Ranch (ACR) has monitored the number of nesting egrets
and herons on West Marin Island since 1979 from viewing positions on East Marin Island
and by boat. In 1993, ACR began monitoring annual reproductive success of great egrets
and great blue herons. The colony is made up of snowy egrets, great egrets, black-crowned
night-herons, and great blue herons. One nesting pair of little blue herons
Draft Comprehensive Conservation Plan 37
(Egretta caerulea) was recorded on West Marin Island in 1965, but has not since been
recorded on the Refuge. (Calif. Dept. of Fish and Game 1967)
It is not known how long the colony has existed on the island. The egret and heron colony
of Marin Island were present around the late 1920s when the islands were privately
owned (Peabody 2004). There are no records of successful nesting by herons and egrets
on East Marin Island despite past nesting attempts. Despite the lack of successful
nesting, herons and egrets use East Marin Island to gather nest material and to roost.
Herons and egrets also forage along the shoreline of East Marin Island.
Great egret fishing
© Greg Block
The number of active heron and egret nests on West Marin Island has ranged from 767 in
1982 to 183 in 2004, with snowy egrets and great egrets comprising the greatest
proportion of total nests. The number of great blue heron nests has increased gradually
since they colonized West Marin Island in 1990 (Kelly and Fischer 2004). A 1993 report
indicates that West Marin Island accounts for 27 percent of the San Francisco Bay Area’s
nesting egrets and herons (Kelly et al. 1993). Approximately 48 percent of snowy egret
nests and 32 percent of black-crowned night-heron nests in the San Francisco Bay Area
occur on West Marin Island (Kelly et al. 1993). Since the annual surveys began, large
annual fluctuations have occurred in the nesting population of egrets and herons on West
Marin Island. Overall, there has been no clear trend in the number of nesting great
egrets and snowy egrets, while great blue herons have recently increased nesting
numbers. There was an apparent decline during the 1980s in the number of nesting black-crowned
night herons on West Marin Island, but abundances have apparently since
stabilized (Kelly and Fischer 2004). However, considerable annual variation persists,
apparently reflecting the between-year movements of nesting birds to and from other
colony sites in the region associated with influences of food availability and disturbance
events.
38 Draft Comprehensive Conservation Plan
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Table 2. 2004 Egret and Heron Colony Survey
Nests in 2004 Nest Survivorship1 Nests in 2003 Nest Survivorship1
Great Egret 83 80% 81 83%
Snowy Egret 59 N/A2 103 N/A2
Black-crowned Night Heron 29 N/A2 51 N/A2
Great Blue Heron 12 73% 10 40%3
1percent of nests fledging at least one young
2conceal their nests
32 of the 10 nests were not able to be monitored
Source: Kelly and Fischer 2004.
Egrets
Great and snowy egrets breed in similar habitats that require proximity to fresh-, salt- or
brackish-water bodies. Both egret species are also platform nesters requiring tall shrubs
and trees several feet high (5-40 feet). At West Marin Island, the great egrets favor
buckeye trees, but also nest in the coast live oak. The snowy egrets place their nests
predominantly in blackberry shrubs although they also use buckeye trees. Number of
active great egret nests has remained relatively stable since 1994 but overall numbers
remain smaller than those observed over the last decade (Kelly and Fischer 2004). The
annual number of active snowy egret nests has varied since 1997, although a steady
decline has been observed since 2001. Since annual monitoring began in 1979, the lowest
count of active snowy egret nests was recorded in 2004.
The first records of raven predation of the heron and egret colony were in 1993. A raven
was observed killing an adult snowy egret in 2001, and each year since 2000, observers
have found the remains of 2 to 14 adult snowy egrets near the common raven nest site on
East Marin Island, suggesting that resident ravens have been killing adult snowy egrets
(Kelly et al. 2005). Other factors contributing to an increase or decrease in the size of the
colony include regional shifts in distribution and changes in habitat quality (e.g.,
vegetative condition). For example, recent declines in the number of active snowy egret
nests may be the result of reduced blackberry cover, which provides predation protection
(Kelly and Fischer 2004). Predation by other species can also lead to nest declines. In
1993 and 1994, repeated disturbance of courting snowy egrets by a red-tailed hawk led to
large-scale nest abandonment and reduced nest numbers through the late 1990s, although
the colony has recovered considerably by 1997. During this period, the number of nesting
snowy egrets increased at other colony sites in the region, including heronries at Red
Rock, Napa State Hospital, and Santa Rosa Creek.
Herons
Great blue herons and black-crowned night herons also generally breed in the same
habitat as egrets (Ehrlich et al. 1998). At West Marin Island, great blue herons generally
nest in California buckeye trees while black-crowned night herons generally nest in
blackberry shrubs and grasses. Great blue herons have shown a consistent increase in
nesting abundance. Great blue herons were sighted on West Marin Island as early as
1970, where one active nest was recorded (Calif. Dept. of Fish and Game 1970). The 2004
survey produced the highest count of nests on record for West Marin Island since birds
colonized on the island in 1990 (Kelly and Fischer 2004). There was an average of 2.43
young counted per nest (pre-fledgling).
Great blue heron
© Greg Block
Black-crowned night-herons on the Refuge showed a continued decline in numbers in 2004
from previous years (Kelly and Fischer 2004). An earlier decline can be attributed to a
fire on the island on July 4, 1981. Like the impacts to the snowy egret colony, raven
predation may also have strong effects on the nesting black-crowned night-heron
population (Kelly and Fischer 2004, Kelly et al. 2005). However, recent declines at the
site may be consistent with annual shifts in distribution to other regional sites. Kelly and
Fischer suggest that some birds on West Marin Island may have moved to a new,
unknown location. Since night-herons conceal their nests in dense vegetation, estimates
may only provide a rough index. Nest survivorship at West Marin Island could not be
determined due to concealed nests.
Contaminant levels among heron and egrets have not been studied in depth to determine
trends and threats to the populations. Mean concentrations of PCBs in black-crowned
night herons in 1989 and egret eggs in 1990 were lower on West Marin Island than at Bair
Island in the South Bay area (Hothem et al. 1995). This could suggest that PCB threats
are lower in the North Bay than the South Bay. However, deformities observed in black-crowned
night heron chicks from West Marin Island resembled those attributed to PCBs
in double-crested cormorants (Hoffmann et al. 1993). Mercury concentrations in egrets
and herons on West Marin Island may result in reproductive impairment (Hoffman et al.
1993). More studies would be needed to determine whether contaminants pose significant
threats to the reproductive success of egrets and herons in the greater San Francisco Bay
Area.
Abundant egrets and herons nesting on West Marin Island suggest the possibility of an
expansion onto East Marin Island. It is not clear why nesting has not yet occurred on
East Marin Island. Human activity or lack of suitable nesting trees could be factors,
40 Draft Comprehensive Conservation Plan
Draft Comprehensive Conservation Plan 41
although East Marin Island may still be a viable alternative nesting area in the event of a
significant habitat loss or nest disturbance at West Marin Island.
Other Breeding Birds
Other bird species that are known to breed at Marin Islands include the western gull,
black oystercatcher, common raven, and Canada goose. Western gulls and cormorants
were sighted on the island as early as 1982 (Pratt 1982). In 1983, geese were sighted and
gull nests appeared to be expanding. Since the sighting in 1983, geese have intermittently
nested or roosted on the island while gull nests have continued to expand. One Canada
goose was observed on West Marin Island in the 2004 surveys. Western gulls are also
present on West Marin Island, with 46 nest sites observed in 2004 (Kelly and Fischer
2004). A single pair of black oystercatchers has been observed nesting annually at West
Marin Island since 1993 (Kelly et al. 1993). At least three pairs of black oystercatchers
were observed throughout the breeding season of 2005 with sightings of two fledglings
along the shoreline of East Marin Island. Oystercatchers were first observed on the
shoreline in 1988.
A single pair of ravens has been present at the Marin Islands since 1990 and were first
observed nesting on East Marin Island in 1999 (Kelly et al. 2005). The resident pair of
ravens successfully fledged three young in 2004 and four young in 2003; they spent much
of their time preying upon heron and egret eggs or young in the heron and egret colony
(Kelly et al. 2005). Shell fragments found near raven nests or cache sites indicate that
heron and egret eggs are taken regularly by ravens; the majority of eggs recovered were
taken from black-crowned night herons (Kelly et al. 2005). Further analysis of prey
remains and predation rate data indicate that resident ravens fulfill most of their energy
requirements taking herons and egrets on West Marin Island (Kelly et al. 2005).
Ironically, ravens may also reduce the threat of predation by other predators. A red-tailed
hawk (Buteo jamaicensis) was observed harassing heron and egret nests, but the
hawk was eventually driven away by the resident ravens (Kelly and Fischer 2004). The
ravens have also been observed chasing peregrine falcons (Falco peregrinus), red-shouldered
hawks (Buteo lineatus), and other raven individuals within the Marin Islands
area. Increases in the number of common ravens in the San Francisco Bay area suggest a
continuing likelihood of raven predation on the Refuge (Kelly et al. 2002, Kelly and Roth
2001).
Nesting Canada goose
© Peter Chan
In the tidal and sub-tidal environments surrounding the islands, several waterfowl and
waterbird species are present during breeding, migratory, or wintering periods. Diving
waterfowl commonly observed include the surf scoter, scaup (Athya spp.), canvasback
(Athya valisineria), western grebe (Aechmophorus occidentalis), ruddy duck (Oxyura
jamaicensis), and bufflehead (Bucephala olbeola). Other species recorded include
common loon (Gavia immer), Clark’s grebe (Aechmophorus clarkia), horned grebe
(Podiceps nigricollis), long-tailed duck (Clangula hyemalis), red-breasted merganser
(Mergus serrator), common golden-eye (Bucephala clangula), and mallard (Anas
platyrhynchos). Waterfowl species known to occur during the summer include the
mallard and scaup. Because scaup breed in more northern latitudes, individuals present
during summer are considered non-breeding for the year.
Waterbirds that commonly roost along the shorelines and forage in the surrounding
mudflats and sub-tidal environments include the brown pelican (Pelecanus occidentalis),
white pelican (Pelecanus erythrorhynchos), double-crested cormorant (Phalacrocorax
auritus), black oystercatcher (Haematopus bachmani), Caspian tern (Sterna caspia),
Forester’s tern (Sterna fosteri), and spotted sandpiper (Actitis macularia). A bird
species table is listed in Appendix D.
Raptors observed in the vicinity include the turkey vulture (Cathartes aura), red-tailed
hawk, red-shouldered hawk, peregrine falcon, American kestrel (Falco sparverius),
white-tailed kite (Buteo albicaudatus), and osprey (Pandion haliaetus). Pellets of great
horned owls (Bubo virginianus) were observed on East Marin Island in 2002.
Mammals, reptiles, and amphibians
During summer 2002, refuge staff surveyed East Marin Island for small mammals
through trapping. No small mammals were captured. Despite known harbor seal (Phoca
vitulina) haul-out sites in the vicinity of the Marin islands, no records exist documenting
this species’ use of the Marin islands. Harbor seals have been observed within the waters
surrounding the islands. No other marine mammals have been recorded in the vicinity of
Marin Islands. The only known reptile species on the islands is the western fence lizard
42 Draft Comprehensive Conservation Plan
Draft Comprehensive Conservation Plan 43
(Sceloporus occidentalis) (east slope of East Marin Island). The California slender
salamander (Batrachoseps attenuatus) was first documented on East Marin Island in
2003. Surveys specific for marine mammals, reptiles, or amphibians have not been
conducted at the Marin Islands.
Fish
A variety of fish species have been sampled in San Rafael Bay; the area is well known for
striped bass (Morone saxatilis) and white sturgeon (Acipenser transmontanus). CDFG
conducts open water trawls and beach seine samples. No species has been identified as
endangered. Appendix E lists the types of fish that are found in the area near the Refuge.
According to the surveys, some of the more abundant fish include the bay goby
(Lepidogobius lepidus), English sole (Pleuronectes vetulus), longfin smelt (Spirinchus
thaleichthys), Pacific staghorn sculpin (Leptocottus armatus), plainfin midshipman
(Porichthys notatus), and speckled sanddab (Citharichthys stigmaeus) (CDFG, unpub.
data).
Federally and State Listed Species at the Refuge
Federally-listed species that have been observed at the Refuge are the California brown
pelican and the previously-listed peregrine falcon. Both of these species do not breed at
the Refuge, but use the islands as roosting and foraging sites. Other species that visit the
Refuge are listed as Species on Concern, which is detailed in Appendix F.
Cultural Resources
Cultural resources are physical remains, sites, objects, records, oral testimony, and
traditions that connect us to our Nation’s past. Cultural resources include archaeological
and historical artifacts, sites, landscapes, plants, animals, sacred locations, and cultural
properties that play an important role in the traditional, and continuing, life of a
community. The currently known cultural resources in and within one mile of the
congressionally authorized boundaries of the Refuge consist of one prehistoric site and
several historic sites.
Cultural resources, especially archaeological sites, are fragile and nonrenewable. Most
consist of worked stone, fire-altered rocks, and organically enriched soil on or close to the
surface. When compared to the surrounding landscape and contemporary cultural
features such as roads, ditches, and structures, archaeological sites are small and subtle.
The Marin Islands have a cultural history of at least 1,300 years. Human occupation of
East Marin Island can be broken into three segments; prehistoric use, military use, and
private residence. Archaeological evidence of prehistoric use from the island
demonstrates Native Americans harvested shellfish, hunted sea mammals, birds, and fish
(Valentine 2005). Along with these faunal remains were found fire-cracked rocks, obsidian
tools, and ground stone, indicating greater variety in island activities than just food
processing. Evidence suggests that a range of subsistence-related and perhaps
44 Draft Comprehensive Conservation Plan
ceremonial activities occurred (Luby 1994). Given the seasonal presence of some of the
animals harvested and the lack of a fresh water source, occupation of the island may have
been seasonal (Valentine 2005).
The early English explorer, Sir Frances Drake is believed to be the first European to
encounter Marin County and the Miwok Indians in the early 1600s. A written account
from a crew member indicates that the area had an abundance of game and fish, including
deer and rabbit. Coastal Miwok Indians inhabiting the San Francisco Bay Area are also
said to have occupied the islands.
In 1824, a Native American leader and a small band of the Coast Miwok took refuge on
East Marin Island to thwart attacks by Mexican military. Popular belief says this leader
was Chief Marin, for whom Marin Islands and Marin County are named. In 1867, the
United States government took control of the islands, along with Alcatraz and Angel
Island, as strategic bases to protect the greater Bay Area. A rock quarry of the south
face of East Marin Island was established to provide material for military installations.
Purportedly portions of the sea wall that are still standing at the northeast corner and
south side of the island were built at this time.
In 1929, the Crowley Launch and Tugboat Company bought the island from the U.S.
Government. The Crowley family constructed two residential houses and related
structures on East Marin Island. The architecture of the buildings is considered
historically important with teak and redwood woodwork and stone work. Bay area
architects Mario Corbett and Clarence Mayhew were responsible for the designs, which
are considered culturally distinct to the 1945 and 1965 time periods they were built. Stone
material was quarried from the north end of East Marin Island to construct San Quentin
Prison, which has resulted in a brackish water pond still present today (pers. comm.,
Peabody). To assist in building and supplying the main house, a small steam engine and
railroad were built. Palm, pine, fruit trees, and other ornamentals were planted and a
garden established.
Social and Economic Environment
Land Use
There are two residential buildings, a pump house, a water tank, storage structures and a
dock on East Marin Island. Figure 6 shows the location of these structures. These
structures were built and used by the previous owners of the islands. These buildings are
in poor condition due to vandalism, and are not currently used by the public. Moreover,
materials used to construct the building contain asbestos and may be considered a health
hazard. Part of the island was quarried to collect rocks for building materials for the two
residential buildings. The quarried area has a lagoon which was used by the previous
owners of the islands. East Marin Island has also been planted with non-native
vegetation by the previous owners. The dock was replaced in 2001.
Draft Comprehensive Conservation Plan 45
Marinas, residential properties, and some commercial properties are located beyond the
Refuge’s boundaries. There are no agricultural properties that would be impacted by
activities on the Refuge.
Traffic and Public Access
Public access is not allowed on West and East Marin Island. However, there have been
illegal dockings by non-motorized vessels, including kayaks. Such trespassing has
resulted in vandalism of the buildings on the Refuge. Refuge management estimates that
trespass occurs once per week. The structures have been ransacked, resulting in broken
glass, damaged doors, and use of non-working bathrooms. Further damage has been
minimized by leaving doors unlocked and disconnecting power. Also, signs are posted
warning trespassers they are prohibited on the Refuge and in any of the building
structures on the Refuge. The waters surrounding the islands are currently open to
boating and the public according to the Public Trust Doctrine of California. Vessels may
pass through water surrounding and between West and East Marin Island, including
those waters within the Refuge’s boundary. Management of the Refuge is not expected to
interrupt boating activities near the Refuge. Some of these vessels fish off the shores of
both islands. Refuge staff accesses East Marin Island by Service small watercraft and a
dock platform, but rarely land on West Marin Island given the island’s sensitive wildlife.
Recreation
There are currently no recreation opportunities on the land portion of the Refuge.
However, recreational boating and fishing from boats does occur in the Refuge’s
tidelands. Also, kayakers and other non-motorized vessels can be seen recreating near
the Marin Islands. Impact of these activities upon wildlife of the Marin Islands is
unknown.
46 Draft Comprehensive Conservation Plan
Draft Comprehensive Conservation Plan 47
Employment
The Refuge is part of a larger economic region in Marin County. For the purposes of this
environmental assessment, that larger region is considered to include the San Francisco
Metropolitan Statistical Area (SF MSA), as defined by the State Employment
Development Department (Employment Development Department 2002). The SF MSA
is dominated by the service industry, which makes up over half of all employment.
An estimated 867,016 jobs are held in the SF MSA (Table 3). The largest employment
sectors are the service sector (51.8 percent of jobs), retail (11.2 percent), and finance and
insurance (8.4 percent).
Table 3. Employment characteristics of the San Francisco
Metropolitan Statistical Area (2002)
Industry Jobs Provided Percent Total
Agriculture 3,552 <1%
Mining 198 <1%
Utilities 7,744 <1%
Construction 46,491 5.4%
Manufacturing 49,057 5.7%
Wholesale Trade 29,302 3.4%
Retail Trade 97,016 11.2%
Transportation and Warehousing 40,400 4.7%
Information 48,809 5.6%
Finance and Insurance 73,214 8.4%
Real Estate and Rental and Leasing 22,369 2.6%
Services 448,864 51.8%
TOTAL 867,016 100%
Source: Employment Development Department 2002
The average unemployment rate in the SF MSA is 4.7 percent, which falls below the
unadjusted unemployment rate of 6.1 percent for California and 5.4 percent for the nation
during the same period (Employment Development Department 2002).
The Refuge prohibits visitors, and therefore, does not contribute directly to the income
and employment of the region. It is not expected that the Refuge will provide or impact
indirect income to the region.
Environmental Justice
On February 11, 1994, the President issued Executive Order 12898 (Federal Actions to
Address Environmental Justice in Minority Populations and Low-Income Populations)
which directs the U.S. Environmental Protection Agency (EPA) to ensure that agencies
analyze environmental effects on minority and low-income communities. The purpose of
the executive order is to avoid the disproportionate placement of any adverse
environmental, economic, social, or health impacts resulting from federal actions and
policies on minority and low-income populations. No specific minority and low-income
48 Draft Comprehensive Conservation Plan
populations have been identified in the community surrounding the San Rafael shoreline
nearest to the Refuge.
Ethnic and Income Characteristics
For compliance with Executive Order 12898, county level data was analyzed to determine
the demographics of the potential impact area. For this environmental justice
assessment, ethnic and income characteristics for Marin County were compared to the
state of California to determine high minority or low-income composition.
According to the information contained in the 2000 census, the total population of Marin
County was approximately 247,289 in 2000 (FAIR 2001). This figure represents a 7.5
percent increase from the 1990 census. Based on the 2000 census, the 2004 population is
estimated to be 250,409. Table 4 below shows the county’s ethnic composition, with
minority populations less than 16 percent of the total population. Marin County’s most
recent estimates for median household income in 1999 were $71,306, while per capita
income was $44,962. Based on 1999 data, 6.6 percent of the persons in the county are
considered below poverty (U.S. Census Bureau 2004).
Table 4. Marin County Ethnicity
Ethnicity Percentage
White 84%
Hispanic or Latino 11%
Asian 4.5%
African-American 2.9%
Source: U.S. Census Bureau 2004
Chapter 4. Challenges and Opportunities
Challenges
The Refuge was established to protect the islands’ egret and heron colony because they
are an important nesting location in the Bay Area. The primary challenges the Refuge
faces are declining habitat, human disturbance and predation of the heron and egret
colony. Located in a highly urbanized environment, species on this Refuge are constantly
faced with habitat loss, habitat fragmentation, and urban development.
Coastal Scrub and Oak Woodland Habitat
The original coastal scrub and oak woodland habitat made up of primarily coast live oak,
buckeye and toyon have been significantly altered due to human habitation of the Refuge.
Past private owners planted a variety of ornamental and fruit-bearing vegetation on East
Marin Island that has resulted in an unfettered expansion that competes with native
vegetation today. Non-native vegetation continues to effectively disperse seeds and
develop on the Refuge. The heron and egret colony is limited to West Marin Island.
Colony reports indicate that individuals have attempted to nest on East Marin Island, but
Draft Comprehensive Conservation Plan 49
never have been successful. Refuge management is uncertain why the colony has not
expanded to East Marin Island. One potential reason could be the abundance of non-native
vegetation that is inappropriate for nesting.
Disturbance
The Refuge is currently closed to the public and there is no refuge staff to provide daily
surveillance. Because of its proximity to the shore, trespassing is believed to be a
common occurrence on East Marin Island, averaging once per week. The structures and
dock on East Marin Island have shown regular evidence of entry and use. Uncontrolled
human presence can cause undesirable impacts to the Refuge, including litter, vandalism,
fires, and disease spread threats to birds and rare plants on the Refuge. This activity and
exposure to marine conditions has led to the deterioration of the buildings and related
infrastructure on East Marin Island.
Ravens were first reported at Marin Islands in 1993. A single pair of ravens occupies the
islands year-round and nests on East Marin Island. During the breeding season, the
colony (eggs, young, adults) may satisfy most or all of the nesting ravens energetic
requirements. Snowy egret and black-crowned night heron eggs, young, and adults have
been the primary target for the ravens. Despite documented predation, monitoring has
not clearly indicated whether this predation has begun to impact productivity of the
colony. Raven predation has resulted in significant declines at other heron and egret
colony sites in the region (e.g., Bolinas Lagoon) and the potential exists for impacts to the
Marin Islands populations.
Wildlife
Aside from the heron and egret colony, black oystercatchers are known to nest on West
Marin Island. However, not enough data is available regarding their needs and threats.
There is verbal, but no recorded evidence of harbor seals hauling out on East Marin
Island. Harbor seals have been found at all other islands in the Bay Area except the
Marin Islands. It is unknown why they have not used the islands.
Chapter 5. Management Direction
The Refuge is one of the increasingly rare coastal areas in the San Francisco Bay where
migratory birds, including herons and egrets, can nest with limited human disturbance.
West Marin Island provides one of only a few remaining nesting locations for local heron
and egret populations in the San Francisco Bay area. The unique assemblage of native
plant communities on the Refuge (especially West Marin Island) is also not found
throughout coastal northern California. In addition, the Refuge contains unique cultural
resources that exemplify the history of San Francisco Bay. Therefore, a comprehensive
plan for managing the Refuge is essential to protect the habitat, wildlife, and cultural
history of the Bay landscape. The CCP presents goals, objectives, and strategies to
50 Draft Comprehensive Conservation Plan
protect these resources during the 15-year lifetime of this plan. Overall goals and
objectives may not be achieved within the 15-year timeframe and will require re-assessment
when the CCP is renewed.
Refuge Vision Statement
The Marin Islands National Wildlife Refuge will provide one of the few protected
sanctuaries of native San Francisco Bay habitat to local and migratory birds in the heavily
urbanized San Francisco Bay area. West Marin Island will provide nesting habitat for
great egrets, black-crowned night herons, snowy egrets, great blue herons, black
oystercatchers, and other colonial nesting waterbirds free from human disturbance. East
Marin Island will, over time, be reverted to native coastal scrub and oak woodland habitat
that may be colonized by the herons and egrets.
Visitors and the community will develop an understanding of the importance of migratory
bird habitat and cultural history in the San Francisco Bay area. A public use program will
provide the local community and visitors with opportunities to experience the unique
resources of the Refuge. The Refuge will be a classroom where visitors will learn about
the wildlife, habitat, and cultural history of San Francisco Bay through compatible
wildlife-dependent recreation delivered by high quality interpretive materials, staff-led
tours, and partnerships. Lastly, the Refuge will have an active and diverse volunteer
group to support the purpose and continued preservation of the Marin Islands.
Refuge Management Goals
Refuge management activities are articulated through goals, objectives, and strategies in
this CCP. The Service defines goal as a “descriptive, open-ended, and often broad
statement of desired future conditions that conveys a purpose, but does not define
measurable units”. Refuge goals are a means to achieving refuge purposes.
The Service defines objectives as concise statements of what will be achieved, how much
will be achieved, and when and where it will be achieved on a refuge. Objectives are
derived from goals and they are accomplished through management strategies. Finally,
strategies specify the action, tools, technique, or combination thereof to meet objectives.
Table 5 and Figure 7 at the end of this chapter describe the management goals,
objectives, and strategies.
Goals were developed to provide management directions in four principal areas: wildlife
management, habitat management, wildlife-dependent public use, and cultural resources.
Goal 1: Maintain and restore, where possible, wildlife communities and coastal scrub and
oak woodland plant communities native to San Francisco Bay, including biological and
physical features that provide optimal habitat for the heron and egret colony, as well as
other coastal wildlife.
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Goal 2: Provide visitors with compatible wildlife-dependent recreational and educational
opportunities to foster an understanding and appreciation of San Francisco Bay native
wildlife and plant communities.
Goal 3: Provide interpretation to instill appreciation within the community and visitors of
the cultural resources and history of the Refuge.
Refuge Objectives and Management Strategies
GOAL 1: Maintain and restore, where possible, wildlife communities and coastal scrub
and oak woodland plant communities native to San Francisco Bay, including biological and
physical features that provide optimal habitat for the heron and egret colony as well as
other coastal wildlife.
The Refuge was established to protect important existing egret and heron colonies on
West Marin Island that serve as one of the largest egret and heron colonies in the San
Francisco Bay area. The Refuge will maintain the colonies nesting on West Marin Island
and encourage expansion of the colonies to East Marin Island. Native coastal plant
communities, particularly the California buckeye and coast live oak woodland, provide
nesting habitat for the egret and heron colony. Although West Marin Island is primarily
composed of this oak-buckeye woodland, East Marin Island is dominated by non-native
vegetation as a result of human disturbance. Habitat restoration activities on East Marin
Island would include removal of invasive plants to be replaced by native plant
communities representative of the Bay Area including oak-buckeye woodland, coastal
scrub, coastal sea-bluff scrub, and coastal grassland scrub. The restored oak-buckeye
woodland on East Marin Island could potentially serve as nesting material or sites for the
colony. In addition, building structures would be removed to provide additional areas for
native plantings.
Objective 1.1:
Over the long-term (15 to 30 years), restore native coastal scrub and oak woodland plant
communities to 75 percent of the area land cover on East Marin Island (totaling
approximately 10 acres) to enhance existing nesting habitat for herons, egrets, and other
migratory birds.
Rationale:
Invasive species represent the single greatest threat to the Refuge System and the
Service’s wildlife conservation mission. East Marin Island’s native plant assemblage is
displaced by non-native vegetation. While vegetation surveys have resulted in a
comprehensive list of species that are present, the extent of native and non-native
vegetation on the Refuge has not been quantified. The current need would be to assess
the extent of non-native species and prioritize removal of these species along with
appropriate timing of native replanting. In the initial implementation of the CCP, it will
52 Draft Comprehensive Conservation Plan
be necessary to inventory and assess all vegetation on the Refuge to develop a timeline for
removal and planting.
Additional nesting habitat and colonization/restoration sites for native plants can be
created through the removal of all building structures on the Refuge. None of the current
buildings and structures on the Refuge is necessary for future management. Moreover,
these buildings and the boat dock have been the target of vandalism by trespassers to the
Refuge despite signage and locking of the facilities. In addition, when trespassers access
the buildings, migratory birds have become trapped inside, resulting in mortality. The
buildings also pose health hazards because interior materials contain asbestos.
Strategies:
• Use the Weed Information Management System (WIMS) and Refuge Lands GIS
(Geographic Information System) to annually inventory and map data on invasive
and native plant colonies including priority species, size of colony, and exact
location.
• Control/eradicate invasive plant species utilizing appropriate integrated pest
management strategies including mechanical and chemical methods. (See
Appendix J and K for detailed table of species, extent of infestations on the Refuge,
timeframe and instruction on removal.)
• Restore and maintain native plants appropriate for nesting habitat and materials
for local birds. (See Appendix J and L for detailed table of species, location of
colony, timeframe and instruction on restoration.)
• Contract removal of non-significant buildings.
Objective 1.2:
Over the life of the Plan, maintain 95 percent of the existing native coastal scrub and oak
woodland plant communities on West Marin Island for heron, egret, and other migratory
bird nesting habitat.
Rationale:
Due to the inaccessibility of West Marin Island, the island has had relatively little human
intrusion resulting in unspoiled native vegetation compared to East Marin Island. Both
the Service and the Refuge System identify native plant conservation as a key component
of their mission. Moreover, the native coastal scrub and oak woodland vegetation on West
Marin Island provides nesting habitat for the herons and egrets. Executive Order 13186
directs federal agencies to ensure that agency plans and actions promote programs and
recommendations of comprehensive migratory bird planning efforts. Maintaining the
native coastal scrub and oak woodland habitat would continue to support the needs of the
herons, egrets and other migratory birds that nest on the Refuge.
Strategies:
• Map native plants and prioritize threats on the entire West Marin Island.
Draft Comprehensive Conservation Plan 53
• Conduct annual surveys to monitor management changes in native and invasive
vegetation through the Refuge Lands GIS and WIMS databases, and adapt
management accordingly.
Objective 1.3:
Within two years of the Plan’s approval, reduce unauthorized trespassing on the Refuge
by 50 percent to minimize vandalism, wildlife disturbance, spre