Kern and Pixley National Wildlife Refuges Draft Comprehensive Conservation Plan and Environmental Assessment

              U.S. Fish and Wildlife Service
Draft
Comprehensive Conservation Plan
and Environmental Assessment
June 2004
Kern and Pixley
National Wildlife Refuges
CCPs 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 sometimes 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.
Kern and Pixley
National Wildlife Refuges
Comprehensive Conservation Plan
Prepared by:
U.S. Fish and Wildlife Service
Region 1
California/Nevada Refuge Planning Office
2800 Cottage Way, W-1916
Sacramento, CA 95825
Kern National Wildlife Refuge Complex
10811 Corcoran Road
Delano, CA 93215
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.).
Table of Contents
Chapter 1. Introduction ............................................................................... 1
Refuge Overview...........................................................................................2
Special Designations ....................................................................................7
Partnerships..................................................................................................7
Management History ...................................................................................9
National Wildlife Refuge System Mission and Goals............................11
Other Landscape-Level Goals ..................................................................11
Refuge Purposes.........................................................................................12
Refuge Vision Statements.........................................................................12
Legal and Policy Guidance ........................................................................13
Chapter 2. Planning Process ................................................................... 17
Planning Process, Planning Time Frame, and Future Revision .........17
Planning Issues...........................................................................................18
Chapter 3. Refuge and Resource Descriptions .................................... 21
Geographic and Ecological Setting ..........................................................21
Soils...............................................................................................................23
Water............................................................................................................26
Air Quality ...................................................................................................30
Plant Communities .....................................................................................31
Wildlife .........................................................................................................39
Special Status Species................................................................................44
Diseases and Toxins ...................................................................................56
Cultural Resources.....................................................................................58
Visitor Services ...........................................................................................61
Socioeconomics............................................................................................65
Chapter 4. Problems and Opportunities................................................. 69
Historic Habitat Destruction and Modification......................................69
Nonnative Plant Species............................................................................69
Contaminants ..............................................................................................70
Water Supply ..............................................................................................71
Lack of Information ...................................................................................72
Chapter 5. Refuge Management Direction: Goals Objectives and
Strategies ..................................................................................................... 75
Kern Refuge ................................................................................................75
Pixley Refuge ..............................................................................................92
Chapter 6. Plan Implementation............................................................ 101
Funding and Staffing ...............................................................................101
Step-Down Management Plans ..............................................................102
Compliance Requirements ......................................................................102
Partnership Opportunities ......................................................................103
Adaptive Management.............................................................................103
Plan Amendment and Revision ..............................................................103
Figures
Figure 1. Watershed / Ecosystem Setting.................................................... 3
Figure 2. Location Map ................................................................................... 4
Figure 3. Land Status - Kern National Wildlife Refuge............................. 5
Figure 4. Land Status - Pixley National Wildlife Refuge........................... 8
Figure 5. Comprehensive Conservation Planning Process ...................... 17
Figure 6. Map of the Southern San Joaquin Valley by Lieut. G. H.
Derby, 1850......................................................................................... 22
Figure 7. Regional Land Cover.................................................................... 24
Figure 8. Land Cover - Kern National Wildlife Refuge ........................... 33
Figure 9. Land Cover - Pixley National Wildlife Refuge ......................... 37
Figure 10. Existing Public Use Facilities ................................................... 60
Figure 11. Average Annual Duck Harvest per Hunter Visit: 1995
to 2002 ................................................................................................. 64
Figure 12. Proposed Habitat Management - Kern Refuge...................... 76
Figure 13. Proposed Visitor Services Plan - Kern Refuge....................... 77
Figure 14. Proposed Habitat Management and Visitor Services Plans -
Pixley Refuge ..................................................................................... 78
Tables
Table 1. Proposed New Step-Down Plans ............................................... 102
Appendices
Appendix A. Environmental Assessment
Appendix B. Wilderness Review
Appendix C. Landscape Level Goals
Appendix D. Compatibility Determinations
Appendix E. Species Lists
Appendix F. Budget Proposal
Appendix G. References
Appendix H. Glossary
Appendix I. List of Preparers
Appendix J. Updated Land Protection Plan: Pixley Refuge
Appendix K. Fire Management Plan
ii
Chapter 1. Introduction
This document is a Comprehensive Conservation Plan (CCP) designed to
guide management at Kern National Wildlife Refuge Complex (Refuge
Complex) for the next 15 years. This Refuge Complex has two refuges,
the Kern National Wildlife Refuge (Kern Refuge) and the Pixley
National Wildlife Refuge (Pixley Refuge). The purposes of this CCP are:
􀂄􈑔 To provide a clear statement of direction for the future management
of Kern and Pixley Refuges (Refuges);
􀂄􈑔 To provide long-term continuity in Refuge Complex management;
􀂄􈑔 To communicate the U.S. Fish and Wildlife Service’s (Service)
management priorities for the Refuges to their neighbors, visitors,
and the general public;
􀂄􈑔 To provide an opportunity for the public to help shape the future
management of the Refuges;
􀂄􈑔 To ensure that management programs on the Refuges are consistent
with the mandates of the National Wildlife Refuge System (Refuge
System) and the purposes for which the Refuges were established;
􀂄􈑔 To ensure that the management of the Refuges is consistent with
Federal, State, and local plans; and
􀂄􈑔 To provide a basis for budget requests to support the Refuge’s needs
for staffing, operations, maintenance, and capital improvements.
This CCP describes the desired future conditions and provides long-range
guidance to accomplish the purposes for which the Refuges were
established. The CCP and environmental assessment (EA) address
Service legal mandates, policies, goals, and National Environmental
Policy Act (NEPA) compliance. A range of administrative, habitat
management and visitor services alternatives that consider issues and
opportunities on the Refuges are presented in the accompanying EA
(Appendix A). The Service’s initial proposal for future management of
the Refuges is presented in this document. The final CCP will be
developed through modifications made during the internal and public
review processes.
Northern pintail. Dave Menke photo.
Chapter 1
2 Kern and Pixley National Wildlife Refuges
Major issues to be addressed during the CCP process include: habitat
protection and enhancement; endangered species management; wetland
restoration and management; nonnative vegetation control; visitor
services management including hunting, wildlife observation,
photography, interpretation and environmental education, and
recreation; visitor services facilities; law enforcement; and visitor
services compatibility.
As a management tool for the Refuge Complex staff to use, this CCP
would guide management decisions, and describe strategies for
achieving Refuge goals and objectives within its 15-year life. The CCP is
divided into six chapters: Chapter 1, Introduction; Chapter 2, Planning
Process; Chapter 3, Refuge and Resources Descriptions; Chapter 4,
Problems and Opportunities; Chapter 5, Refuge Management Direction:
Goals, Objectives and Strategies; and Chapter 6, Plan Implementation.
Refuge Overview
Introduction to Kern and Pixley Refuges
Kern and Pixley Refuges are part of a network of 15 national wildlife
refuges and wildlife management areas in California’s Central Valley
and San Francisco Bay region that provide wintering habitat for
migratory waterfowl and other waterbirds in the Pacific Flyway (Figure
1). The Refuges are located in the southern end of California’s San
Joaquin Valley (Figure 2). Chapter 4 presents a detailed description of
the natural resources on Kern and Pixley Refuges.
Refuge Establishment and Acquisition History
Kern Refuge. When the area and number of wetlands and private duck
clubs decreased during the 1930s and 1940s, Kern County sportsmen
became alarmed. During this same time, the Service was actively
pursuing suitable land for establishing wildlife refuges in Kern, Kings,
and Tulare Counties. In 1957, the Service began negotiating with the
Allison Honer Company for the purchase of 16 sections of land in
northwest Kern County.
On March 11, 1958, the Migratory Bird Conservation Commission, under
the authority of the Migratory Bird Conservation Act, approved the
purchase of lands to create the Mariposa National Wildlife Refuge,
known today as the Kern National Wildlife Refuge.
On November 18, 1960, the Service purchased 10,544 acres from the
Allison Honer Company. On September 16, 1963, an additional 74 acres
were purchased from Miller and Lux. to obtain the remaining acreage
within the approved and current 10,618-acre Kern Refuge boundary
(Figure 3).
Justification for establishing the Kern Refuge included:
􀂄􈑃 Construction of Lake Isabella Reservoir reduced the areas available
for waterfowl use in this ancestral wintering ground of the birds of the
Pacific Flyway.
Introduction
Comprehensive Conservation Plan 3
Figure 1. Watershed / Ecosystem Setting
Kern National
Wildlife Refuge
Fresno
San Diego
Sacramento
Los Angeles
San Francisco
Pixley National
Wildlife Refuge
Redding
Bakersfield
Modesto
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BITTER
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NWR
STONE
LAKES
NWR
SAN
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NWR
DON EDWARDS
SAN FRANCISCO
BAY NWR
SACRAMENTO
NWR
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NWR
SUTTER
NWR
BLUE
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NWR
MARIN
ISLANDS
NWR
ANTIOCH
DUNES
NWR
SAN JOAQUIN
RIVER NWR
BUTTE SINK
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NWR
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GRASSLANDS
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CA/NV Refuge Planning Office - Feb 2004
Pacific
Flyway
Area
Enlarged
Figure 1. Watershed / Ecosystem Setting
50 25 0 50
Miles
I
National Wildlife Refuges
Kern and Pixley
Tulare Lake Watershed
Central Valley-San Francisco Bay Ecoregion
Chapter 1
4 Kern and Pixley National Wildlife Refuges
Figure 2. Location Map
Introduction
Comprehensive Conservation Plan 5
Figure 3. Land Status: Kern National Wildlife Refuge
Chapter 1
6 Kern and Pixley National Wildlife Refuges
􀂄􈑁 Agricultural and other development have reduced waterfowl wintering
habitat (feeding and resting areas) until the lack of such habitat has
become the principal limiting factor in the maintenance of the
waterfowl resource in the Pacific Flyway. It is essential that
additional habitat be provided for the maintenance of the resource.
􀂄􈑔 The Kern site would obtain better distribution of the waterfowl
throughout the wintering grounds, thereby alleviating the present
trend toward increasingly heavy concentrations farther north.
􀂄􈑗 Would provide opportunity for public hunting in the area.
􀂄􈑅 Establishing and developing the refuge would replace part of the
waterfowl habitat lost to agricultural and other development in a
region formerly used heavily by migrating and wintering birds.
Restoring this habitat would attract and hold large numbers of
waterfowl, thereby improving hunting opportunities in the general
area and, by obtaining wider distribution of the wintering population,
reduce waterfowl depredations to crops in the lower San Joaquin
Valley (MBCC 1958, Service 1961).
A number of entities hold easements on portions of Kern Refuge. Kern
County was granted 30-foot wide easements on the east, west, and south
boundaries for public roads. There are also two 10-foot wide gas pipeline
easements, a 25-foot wide electric power line easement, and a 15,000
square-foot easement for a gas dehydration station. A perpetual water
distribution easement on the Goose Lake Canal may now be terminated.
The Service claims that a five-year period of non-use reverts control of
the four-mile stretch to the Refuge. This claim has yet to be legally
determined.
Pixley Refuge. In the 1920s and 1930s, title to large areas of former
homestead tracks near Pixley, California reverted to the United States
government. These lands, which were considered marginal for farming,
were administered by the U.S. Department of Agriculture (USDA)
under the Bankhead-Jones Farm Tenant Act.
On November 6, 1958, Executive Order 10787 transferred more than two
million acres of USDA lands, including approximately 4,350 acres in
Tulare County, to the U.S. Department of Interior. On November 17,
1959, the land in Tulare County was transferred to the Service under the
Secretary of the Interior Order 2843. This action created Pixley Refuge,
which was to be administered under the Migratory Bird Conservation
Act for migratory birds and other wildlife.
From 1964 through 1966, the under the authority of the Migratory Bird
Conservation Act, the Service exchanged approximately 607 acres of
land at Pixley Refuge for approximately 410 acres of land. This action
was done primarily to acquire inholdings within the Refuge boundary.
On January 7, 1980, under the authority of the Endangered Species Act
of 1973, the Service Director approved an expanded boundary for Pixley
Refuge. This action identified approximately 4,600 acres of land that
could be acquired for the protection of the endangered blunt-nosed
leopard lizard. The Refuge boundary was expanded again in the 1985
Introduction
Comprehensive Conservation Plan 7
Master Plan. The current approved refuge boundary contains
approximately 10,300 acres, of which the Service owns approximately
6,385 acres in fee; and 4.5 acres are under easement with a private
landowner for access purposes (Figure 4). The remaining 3,911 acres
are privately owned.
Many of the 27 parcels that the Service owns at Pixley Refuge have
easements, rights-of-way, and outstanding mineral rights held by other
entities. The most significant of these are the access easements to the
Deer Creek Channel and County Road 88, which run through the
Refuge.
Special Designations. In 1974, the San Joaquin Desert Research
Natural Area (RNA) was established at Kern Refuge to preserve 2,260
acres of native upland. The RNA originally included all Refuge lands
west of Goose Lake Canal in units 11 and 12 and the northern third of
unit 14. In 1995, the northern third of unit 14 was removed from the
RNA and unit 10 was added. In accordance with the Service’s refuge
planning policy, a wilderness review of Kern and Pixley Refuges was
conducted during the CCP process (see Appendix B). Neither refuge
was found suitable for wilderness designation.
Partnerships. Partnerships with various organizations and agencies
have greatly expanded opportunities for both Kern and Pixley Refuges
to achieve goals and objectives by implementing habitat improvement,
biological monitoring, and public use projects. Both Ducks Unlimited
and California Waterfowl Association have secured and implemented
grants for habitat improvement projects on Kern Refuge that essentially
doubled the quantity of moist soil habitat and significantly improved
water management capabilities throughout the Refuge. Agreements
with the Endangered Species Recovery Program operating from
California State University Stanislaus permit their biologists to monitor
refuge populations of endangered species, greatly supplementing the
data gathering efforts of Refuge staff.
Tulare County Audubon (TCA) obtained a matching fund grant from the
National Fish and Wildlife Foundation to construct a self-guided
interpretive trail on Pixley Refuge. The Service then funded an
observation platform that was constructed at the terminus of the trail
primarily with volunteer labor provided by TCA members. This was the
first time that any portion of Pixley Refuge has been open to
unsupervised use by the public.
The longest standing cooperative association for the Refuge Complex is
with the California Department of Fish and Game (CDFG). Operating
continuously since 1973 through this agreement, the public hunting
program on Kern Refuge is administered by the CDFG. In addition to
the hunt program, CDFG also works cooperatively with the Service to
monitor and when necessary, manage waterfowl disease outbreaks in the
southern San Joaquin Valley.
Without the cooperative efforts of these and other organizations and
agencies, the scope and depth of Refuge programs would be significantly
reduced.
Chapter 1
8 Kern and Pixley National Wildlife Refuges
Figure 4. Land Status: Pixley National Wildlife Refuge
Introduction
Comprehensive Conservation Plan 9
Management History
Kern Refuge
Prior to establishment of Kern Refuge, much of the land that is now part
of units 13 and 14 were actively farmed by the Allison Horner Company
for a variety of small grain crops. To allow for cultivation of these fields,
much of the area was partially leveled and numerous levees and canals
were constructed throughout the area to facilitate water distribution and
drainage. Approximately 1,400 acres west of Goose Lake Canal were
manipulated in this way.
Historic management of the area east of Goose Lake Canal consisted
primarily of grazing by both cattle and sheep. While this area did not
consistently contain wetlands, the area was characterized by uplands
that supported perennial grasses and scrub vegetation interspersed with
swales that contained water during years of normal or higher
precipitation.
Early development of the Refuge focused primarily on the area east of
Goose Lake Canal with an emphasis on creating wetlands. This included
drilling 10 deep water wells, construction or renovation of 35 miles of
levees, excavation of 7 miles of water distribution ditches, and placement
of numerous water control structures. Additionally, an extensive system
of levee supported roads was developed and used for water management,
public access, and all weather access to critical areas of the Refuge.
While much of the developed area consisted of seasonal marsh,
approximately 1,200 acres within units 4, 5, and 6 were leveled to allow
maximum use of the limited water supplies available to the Refuge, and
managed as moist soil units.
During the initial development of the Refuge, water to support the newly
developed wetlands was to be supplied from wells drilled on the east half
of the Refuge. When this source became cost prohibitive and the well
output was insufficient to meet Refuge needs, the purchase of surface
water was pursued. Due to Refuge budget constraints, water sufficient
to flood only approximately 2,500 acres, was normally available. The
passage of the Central Valley Project Improvement Act in 1992 provided
the Refuge with a more reliable and abundant water supply. Now that
full development (Level 4) water supplies are being obtained by the
Bureau of Reclamation, approximately 6,400 acres of wetlands can be
flooded and maintained on the Refuge. For a more detailed description
of water development and management on Kern Refuge see the Water
section in Chapter 3 (page 26).
This dramatic increase in water availability has changed the overall
management and appearance of the Refuge. The Service now manages a
greater quantity and variety of wetland habitats on the Refuge
including: summer water for colonial nesting species such as great blue
herons and white-faced ibis; late summer waterfowl habitat for early
migrant ducks; greatly expanded opportunities to provide moist soil
habitat; and greater flexibility in irrigation schedules of marsh
vegetation.
Chapter 1
10 Kern and Pixley National Wildlife Refuges
Pixley Refuge
Historic records indicate that the western portion of the Pixley Refuge
had been extensively cultivated while the eastern areas were used
primarily as grazing land. For some undocumented reason, possibly
increased soil salinity, farming on the lands that eventually became the
Refuge was abandoned. At the time of Refuge establishment, no
farming was being conducted. Areas in the Center Field Unit still show
evidence of cultivation and the existence of irrigation or drainage ditches
and small reservoirs.
Beginning in 1963 and continuing into the following year, initial
development of the Refuge included the creation of a series of wetland
impoundments in Sections 19, 20 and 21 that totaled 797 acres. In an
effort to supply the water needs of the Refuge, an irrigation well was
drilled in 1962 but failed to produce the necessary quantity of water.
With inadequate wells, water supplies for the Refuge were limited to
seasonal runoff from the Deer Creek watershed and were only available
in years of high precipitation and normally occurred late in the winter or
early spring. Due to this sporadic nature of the wetlands on the Refuge,
only limited use of the area by waterfowl occurred until development of a
high production water well in 1992.
With the advent of a reliable well, active management of approximately
one-half of the wetlands began in earnest when a moist soil management
program was initiated in 1992. The response by waterfowl and
waterbirds to the availability of wetlands in the Tulare Lake basin was
excellent.
During the initial acquisition of lands for the Pixley Refuge,
approximately 3,180 acres of uplands were acquired. With passage of
the Endangered Species Act in 1973, management of these uplands for
the benefit of listed species, took on additional importance. Between
1981 and 1994, an additional 2,230 acres of uplands were acquired for the
management of threatened and endangered species.
Blunt-nosed leopard lizard. Fish & Wildlife Service photo.
Introduction
Comprehensive Conservation Plan 11
In an effort to improve the annual grasslands on the Refuge for the
benefit of the listed species present, a closely monitored grazing
program utilizing cattle supplied by Refuge permittees was initiated. To
facilitate this program, a stock water well was drilled in the Center Field
Unit in 1972. This is the only active program currently in place to
effectively manage the uplands of the Refuge.
National Wildlife Refuge System Mission and Goals
Established in 1903 by President Theodore Roosevelt, the 94-million-acre
Refuge System now includes over 540 National Wildlife Refuges,
thousands of small wetlands, and other special management areas in 50
states and several territories. Most National Wildlife Refuges are
strategically located along the major bird migration corridors,
ensuring that ducks, geese, and songbirds have rest stops on their
annual migrations. Many refuges were established to protect
endangered or threatened species or key sensitive habitats, such as
offshore nesting seabird colonies.
The mission of the Refuge System is to administer a national network
of lands and waters for the conservation, management, and where
appropriate, restoration of the fish, wildlife, and plant resources and
their habitats within the United States for the benefit of present and
future generations of Americans (National Wildlife Refuge System
Improvement Act of 1997).
The goals of the Refuge System are:
􀂄􈑔 To preserve, restore, and enhance in their natural ecosystems (when
practicable) all species of animals and plants that are endangered or
threatened with becoming endangered;
􀂄􈑔 To perpetuate the migratory bird resource;
􀂄􈑔 To preserve a natural diversity and abundance of fauna and flora on
refuge lands;
􀂄􈑔 To provide an understanding and appreciation of fish and wildlife
ecology and the human’s role in the environment; and
􀂄􈑔 To provide refuge visitors with high-quality, safe, wholesome, and
enjoyable wildlife-oriented recreational experiences, to the extent that
these activities are compatible with the purposes for which the refuge
was established.
Other Landscape-Level Goals
Several different landscape-level plans and programs have goals that are
applicable to Kern and Pixley Refuges, including:
􀂄􈑃 CALFED Ecosystem Restoration Program;
􀂄􈑃 Central Valley Habitat Joint Venture Implementation Plan;
􀂄􈑒 Riparian Bird Conservation Plan (California Partners in Flight and
the Riparian Habitat Joint Venture);
􀂄􈑐 Pacific Flyway Management Plan: Western Management Unit
Mourning Dove;
􀂄􈑓 Southern Pacific Coast Regional Shorebird Plan;
􀂄􈑋 Kern County General Plan;
􀂄􈑒 Recovery Plan for Upland Species of the San Joaquin Valley,
California; and
Refuge System Mission:
“ . . . 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”
Chapter 1
12 Kern and Pixley National Wildlife Refuges
􀂄􈑓 Service/California Department of Fish and Game Tricolored
Blackbird Status Update and Management Guidelines.
The relevant goals from each of these plans are listed in Appendix C.
Refuge Purposes
The Service acquires Refuge System lands under a variety of legislative
acts and administrative orders. The transfer and acquisition authorities,
used to obtain the lands, usually have one or more purposes for which
land can be transferred or acquired. These purposes, along with the
Refuge System mission, form the basis from which and the standard by
which the Service determines if refuge uses are compatible.
Kern Refuge was established under the authority of the Migratory Bird
Conservation Act for use “. . . as an inviolate sanctuary, or for any other
management purpose, for migratory birds” (16 U.S.C. § 715d).
Pixley Refuge was established to provide wintering habitat for
migratory birds and protect habitat for the endangered blunt-nosed
leopard lizard. The authorities and corresponding purposes for which
Pixley Refuge was established are: (1) Bankhead-Jones Farm Tenant
Act “. . . a land-conservation and land-utilization program . . .” 7 U.S.C. §
1011; (2) Secretarial Order 2843, dated Nov. 17, 1959 “. . . for migratory
birds and other wildlife . . .”; and (3) Endangered Species Act of 1973
“. . . to conserve (A) fish or wildlife which are listed as endangered
species or threatened species . . . or (B) plants . . .” 16 U.S.C. § 1534.
Refuge Vision Statements
A vision statement is a concise statement of what a refuge should be,
based primarily on the Refuge System mission, specific refuge purposes,
and other mandates. A vision statement helps articulate the direction
the refuge should be heading. Vision statements for Kern and Pixley
Refuges follow:
Kern Refuge
Kern Refuge is representative of a once extensive complex of native
wetlands and uplands and currently is the largest wetland complex
managed for wildlife in the southern San Joaquin Valley. With a secure
water supply, Kern Refuge will provide reliable, high-quality wetland
habitat to meet the needs of wintering and migrating waterfowl and
waterbirds. The Refuge’s riparian corridors and seasonal wetlands will
support a rich diversity of migratory songbirds, colonial nesting species,
and raptors. Remnant valley-floor uplands will be preserved and
restored for native plant and animal species. These uplands will support
populations of threatened and endangered species including the blunt-nosed
leopard lizard, Tipton kangaroo rat, San Joaquin kit fox, and
Buena Vista Lake shrew. To meet the demands of the rapidly growing
population of the southern San Joaquin Valley and to accommodate more
than 50,000 visitors annually, the Refuge will provide opportunities for
high-quality wildlife-dependent visitor services, including hunting,
wildlife observation, environmental education, and interpretation. These
visitor services opportunities will increase the public’s understanding of
Introduction
Comprehensive Conservation Plan 13
and appreciation for wildlife and the importance of conserving their
habitat.
Pixley Refuge
Pixley Refuge represents one of the few remaining examples of the
grasslands, vernal pools, and playas that once bordered the historic
Tulare Lake. Management of these diverse natural communities will
focus on providing high-quality habitat for threatened and endangered
species including the blunt-nosed leopard lizard, Tipton kangaroo rat,
San Joaquin kit fox, and vernal pool fairy shrimp. Natural lands
between the Refuges will be protected through conservation easements,
partnerships, and willing-seller acquisition to provide linkage areas for
these species. Managed wetlands and adjacent grasslands will provide
high-quality habitat for wintering and migratory waterfowl and
waterbirds, including sandhill cranes. Restored riparian corridors will
support a rich diversity of migratory songbirds and raptors. Pixley
Refuge will provide unique opportunities for compatible wildlife-dependent
visitor services which will increase the public’s understanding
of and appreciation for wildlife and the importance of conserving wildlife
habitat.
Legal and Policy Guidance
Refuges are guided by the mission, goals, and purpose of the Refuge
System, Service policy, legal mandates, international treaties, and refuge
purposes. Key concepts in the laws, regulations, and policies that guide
management of the Refuge System include primary versus multiple-use
public lands, compatibility, and priority wildlife-dependent recreational
activities. Examples of relevant guidance include the National Wildlife
Refuge System Administration Act of 1966, as amended by the National
Wildlife Refuge System Improvement Act of 1997 (Improvement Act),
Refuge Recreation Act of 1962, Executive Order 12996 (Management
and General Public Use of the National Wildlife Refuge System), and
selected portions of the Code of Federal Regulations and the Service
Manual.
The Refuge Recreation Act, as amended, authorized the Secretary of the
Interior to administer refuges, hatcheries, and other conservation areas
for recreational use when such uses did not interfere with the area’s
primary purpose. The National Wildlife Refuge System Administration
Act of 1966, as amended, provides guidelines and directives for the
administration and management of all areas in the Refuge System, for
the protection and conservation of fish and wildlife threatened with
extinction, wildlife ranges, game ranges, wildlife management areas, and
waterfowl production areas. Use of any area within the Refuge System
was permitted, provided that such uses were compatible with the major
purposes for which such areas were established.
Executive Order 12996 (March 23, 1996) 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, organizations, industry, and the general public; mandated public
Chapter 1
14 Kern and Pixley National Wildlife Refuges
involvement in decisions on the acquisition and management of refuges;
and required identification, prior to acquisition of new refuge lands, of
existing compatible wildlife-dependent uses that would be permitted to
continue on an interim basis pending completion of comprehensive
planning.
The Improvement Act defined a unifying mission for the Refuge System;
established the legitimacy and appropriateness of the six priority visitor
services; established a formal process for determining compatibility;
established the responsibilities of the Secretary of the Interior for
managing and protecting the Refuge System; and required a CCP for
each refuge by the year 2012. The Improvement Act amended portions
of the Refuge Recreation Act and National Wildlife Refuge System
Administration Act of 1966.
Unlike other Federal lands, which are managed under a multiple-use
mandate (e.g., national forests administered by the Forest Service and
public lands administered by the Bureau of Land Management), the
Refuge System is managed specifically for the benefit of fish, wildlife,
and plant resources and their habitats. Compatible wildlife-dependent
recreation is a legitimate and appropriate general visitor service of the
Refuge System. Wildlife-dependent public uses include hunting, fishing,
wildlife observation and photography, and environmental education and
interpretation are priority visitor services of the Refuge System. These
uses must receive enhanced consideration over other visitor services in
refuge planning and management.
Before any uses, including wildlife-dependent recreational activities, are
allowed on a refuge, Federal law requires that they be formally
determined to be “compatible.” A compatible use is defined as a use
that, in the sound professional judgment of the refuge manager, would
not materially interfere with or detract from the fulfillment of the
Refuge System mission or the refuge purposes. Sound professional
judgment is defined as a finding, determination, or decision that is
consistent with: the principles of sound fish and wildlife management and
administration, available science and resources (funding, personnel,
facilities, and other infrastructure), and applicable laws. If financial
resources were not available to design, operate, and maintain an activity,
the refuge manager would take reasonable steps to obtain assistance
from the state and other conservation interests.
The Service has completed draft compatibility determinations for the
Refuges (Appendix D). Five of the six priority wildlife-dependent
recreational activities were determined to be compatible for the Kern
Refuge: hunting, wildlife observation, wildlife photography,
environmental interpretation, and environmental education. Four of the
six priority wildlife-dependent recreational activities were determined to
be compatible for Pixley Refuge: wildlife observation, wildlife
photography, environmental interpretation, and environmental
education. Fishing was not evaluated at either Refuge due to the lack of
fishing opportunities. Hunting was not evaluated at Pixley for two
primary reasons. First, the Refuge’s wetland unit is too small to manage
as a hunt area. It would require a disproportionate amount of staff time
and resources for the small number of hunters potentially
Introduction
Comprehensive Conservation Plan 15
accommodated. Second, Pixley Refuge is an important wintering area
for sandhill cranes. The cranes are sensitive to disturbance and would
likely stop using the Refuge if hunting were allowed.
Chapter 1
16 Kern and Pixley National Wildlife Refuges
Comprehensive Conservation Plan 17
Chapter 2. Planning Process
Planning Process, Planning Time Frame, and Future Revision
The first Planning Update for the Kern and Pixley Refuges CCP was
distributed in August 1999. It announced public workshops held on
August 30 and 31, 1999, to identify issues and concerns and described
interim goals. In a Federal Register Notice dated August 16, 1999, the
Service announced that it was preparing a CCP for Kern and Pixley
Refuges. The second Planning Update, released in March 2000,
described the issues, concerns, and opportunities identified at the public
workshops, and the draft vision statements for the Refuges. The third
Planning Update, released in March 2002, described the draft
alternatives for managing Kern and Pixley Refuges.
The development of this draft CCP was guided by the Refuge Planning
Chapter of the Fish and Wildlife Service Manual (Part 602 FW2.1,
November 1996). Key steps included: (1) preplanning; (2) identifying
issues and developing a vision; (3) gathering information; (4) analyzing
resource relationships; (5) developing alternatives and assessing
environmental effects (see Appendix F for environmental assessment);
(6) identifying a preferred alternative; and (7) publishing the draft CCP.
The next steps in this process include soliciting public comments on the
draft CCP, preparing the final CCP, obtaining approval from the
California/Nevada Operations Manager, and finally, implementing the
CCP.
Figure 5. CCP Process.
Figure 5. CCP Process
Final
CCP
Prepare Draft
CCP
Develop
Alternative Objectives
And Strategies
Implement
CCP
And Monitor
Review and
Revise the
CCP
Public Scoping &
Identify Issues
Develop Vision
Statement &
Goals
Initiate Study
Preplanning
CCP
Process
Public
Input
Public
Input
Public
Input
Public
Input
Chapter 2
18 Kern and Pixley National Wildlife Refuges
Once finalized, this CCP will be annually reviewed by Refuge Complex
staff while preparing work plans and updating the Refuge information
management system database. It may also be reviewed during routine
inspections or programmatic evaluations. Results of the reviews may
indicate a need to modify the CCP. Monitoring objectives is an integral
part of the CCP, and management activities may be modified if desired
results are not achieved. If minor changes are required, the level of
public involvement and associated NEPA documentation will be
determined by the project leader. The CCP will be formally revised at
least every 15 years.
Planning Issues
Issues, concerns, and opportunities were identified through discussions
with planning team members, key contacts, and through the public
scoping process, which began with two public workshops in August 1999.
Verbal and written comments were received at the meetings. The
following issues, concerns, and opportunities are a compilation of
information developed by the Service throughout the planning process.
General
In general, commenters supported the Refuges and approved of the
current management. Three people recommended that the CCP be
coordinated with other conservation efforts in the region. One
commenter suggested that Kern Refuge should be kept in its current
condition. Another commenter stated that current water allocations
should be maintained or increased if possible.
Wildlife and Habitat Management
The Service received a variety of comments relating to wildlife
management. A few people commented on managing for specific species.
For example, one commenter suggested that the Service replace chain
link fencing with larger mesh to avoid a possible choking hazard to kit
foxes. Another person suggested that Kern Refuge should emphasize
management of tricolored blackbirds.
Several people commented on existing management practices at the
Refuges. Three commenters suggested that cattle grazing should be
continued as a management tool on the Refuges. Four people suggested
that vegetation in unit 1 should be better controlled to provide more
open water habitat. Another person commented that the Refuges should
ensure that vegetation management practices in the marsh are sensitive
to migratory birds that use vegetation in the spring and summer.
Other commenters suggested that the Service could adopt new wildlife
management measures, including reintroducing large native game, or
offering incentives to adjacent landowners to grow wildlife-friendly
crops. Finally, one person suggested that the status and distribution
information for all the natural resources on the Refuges should be
updated.
Planning Process
Comprehensive Conservation Plan 19
Visitor services
The Service received more comments on visitor services than any other
category. These comments fall into three main categories: facilities and
staffing; hunting; and nonconsumptive recreation. Under the first
category (facilities and staffing), commenters suggested building more
public restrooms at Kern Refuge, with Service staff on the Refuge at all
times to prevent vandalism. Other commenters suggested that more
parking lots be made available at Kern Refuge and that a parking lot
should be constructed for visitors to Pixley Refuge.
Comments on hunting were varied. Several commenters expressed
support for the hunting program at Kern Refuge. Another commenter
stated that hunting and trapping are not compatible with the Refuge
purposes. Two people requested that more youth-hunt days be planned.
Several people commented on the areas open to hunting at Kern Refuge.
Comments ranged from increasing the hunting area at Kern Refuge to
closing particular units. Other commenters suggested rotating the open
and closed units. One person requested that Pixley Refuge be opened to
hunting.
Several people commented on the reservation system. Some comments
supported the existing system while others were opposed to it and
suggested changes. One person suggested that the Kern Refuge offer
three types of hunting passes: hunting from blinds, free roaming, and
hunting from dikes. Four commenters requested that more hunters be
accommodated on hunt days.
A number of people suggested changes in the hunting regulations. Two
commenters requested that the Service allow hunting on Sundays. One
person suggested that hunters be allowed to start a half-hour or an hour
earlier. Another person requested that the current 25-shell limit be
maintained and that enforcement be increased. One commenter
suggested that motion decoys be prohibited. Another person
recommended that the Service adopt a blind limit of two adult hunters
per blind.
The Service received a variety of comments and ideas on
nonconsumptive recreation. One person suggested that a birder’s board
be established outside the new Refuge Complex office where birders
could record their sightings. Two commenters suggested that the
Service establish a second tour route at Kern Refuge that could be used
by non-hunters on hunt days. Several comments addressed Pixley
Refuge specifically. One commenter requested that a signed nature trail
and viewing platform be developed at Pixley Refuge. Another person
said the Service should address the liability issues of concurrent use by
the public of areas where permittee livestock may interact with visitor
services, such as birdwatching.
Outreach/Environmental Education
One commenter suggested that the Service produce an educational video
about the Refuges and make a concerted effort to involve area schools.
The same commenter suggested that the Service conduct a publicity
campaign highlighting Refuge Complex restoration efforts and the
Chapter 2
20 Kern and Pixley National Wildlife Refuges
resulting benefits. Finally, another person suggested that the Service
put a Watchable Wildlife sign on Highway 99 to direct visitors to Pixley
Refuge.
Acquisition
A number of commenters suggested that the Service expand the
Refuges, to provide protected corridors between the Refuges and other
conservation areas in the San Joaquin Valley. Another person suggested
that the Service acquire lands at the boundaries of Kern Refuge to
secure feeding habitat for tricolored blackbirds. Finally, another
commenter recommended that the Service acquire the remaining private
lands within the Pixley Refuge approved boundary.
Comprehensive Conservation Plan 21
Chapter 3. Refuge and
Resource Descriptions
Geographic and Ecological Setting
Geographic Setting
The Refuge Complex is in the southern San Joaquin Valley (Valley)
which is formed by the Sierra Nevada Mountains on the east and the
Coastal Range on the west. Elevations in the Valley decrease toward the
north and average 220 feet above mean sea level on the Refuge Complex.
Historic and present drainage of the Valley and the Kern Complex is
also toward the north.
Kern Refuge, surrounded by agricultural lands and private duck clubs,
represents the largest area (10,600 acres) managed for wildlife and
plants in the southern portion of the Valley. Two major highways,
Interstate 5 and Highway 99, run north and south through the Valley
and are 20 miles to the east and 10 miles to the west of the Kern Refuge,
respectively. One public road, Corcoran Road, borders the entire
eastern edge of Kern Refuge. The closest town, Delano, is 20 miles to
the east with a population of 22,800. Bakersfield is about 40 miles to the
southeast and Fresno is 70 miles north of the Refuge.
Pixley Refuge is surrounded by agricultural lands that support a
growing dairy industry. Highway 99 is 9 miles to the east and Highway
43 is 3 miles to the west; both run north and south and are connected by
Avenue 56, which is approximately 2 miles south of the Pixley Refuge.
The closest towns are Alpaugh, 8 miles to the west with a population of
900, and Earlimart, 8 miles to the east with a population of 900. The
Tulare, Visalia, and Hanford area, with a combined population of 138,000,
is approximately 30 miles north of Pixley Refuge on State Highway 99.
Historic Environment
Geologic data and historic accounts describe the southern Valley as a
vast sea that as recently as 100 years ago covered at least 800 square
miles in Tulare, Kings, and Kern Counties (Howard 1979, PG&E 1970).
Rivers and streams flowed from the Sierra Nevada Mountains to the
east of the Valley creating lush wetlands, riparian corridors, and lake
basins. Tulare Lake, the largest lake basin and lowest point in the
Valley, served as an endpoint for this system. Outflow to the Pacific
Ocean via the Sacramento-San Joaquin Delta to the north, occurred in
flood years (Figure 6). Despite being the driest portion of the Central
Valley, the Tulare Basin historically contained the largest block of
wetland habitat in California (about 260,000 acres of permanent wetlands
and another 260,000 acres of seasonal wetlands) (CVHJV 1990).
American settlement of the Tulare Lake Basin was spurred by
development elsewhere in California, especially the increasing demand
for food during the gold rush and the urbanization of San Francisco and
the Sacramento-San Joaquin Delta (Preston 1981). By the 1860s, the
once isolated and self-sufficient Tulare Lake Basin provided agricultural
Chapter 3
22 Kern and Pixley National Wildlife Refuges
crops to more urbanized areas in the State and was dependent on these
areas for goods and services.
Agriculture played the most significant role in transforming the
southern Valley from one dependent on natural processes, rainfall, and
snowmelt, to one dependent on water diversions and groundwater
pumping for the production of crops. While this greatly benefited the
small agricultural communities that formed throughout the Valley, as
more and more native uplands, wetlands, rivers and streams were
converted to agricultural production, there were adverse impacts to
native wildlife (Preston 1981). The extent of Tulare Lake and the
supporting marshlands, smaller lake basins to the south, and rivers and
streams from the Sierra Nevada Mountains to the east, were radically
altered. By 1900, increased salinity and reduced water flows into the
Figure 6. Map of the southern San Joaquin Valley by Lieut. G. H. Derby, 1850
Figure 6. Map of the southern San Joaquin Valley by Lieutenant G. H. Derby, 1850. Note: Tulare
Lake is labeled Tache Lake on this map.
Refuge and Resource Descriptions
Comprehensive Conservation Plan 23
Valley resulted in the demise of fisheries throughout the region as well
as a large commercial fishing enterprise on Tulare Lake (Preston 1981).
Today, the southern Valley is characterized by a patchwork of
agricultural fields, orchards, and vineyards connected to, and dependent
on, a network of water districts and water delivery canals (Figure 7).
Native wetlands are virtually nonexistent because the water has been
diverted for agricultural purposes. When flooding occurs, the historic
lake basins, marshes, streams, and rivers, that were converted to
agricultural lands, still carry the majority of the water through the
Valley. However, sheet flooding across urban and upland areas is
common. Riparian habitat was once common along streams and rivers in
the Central Valley. Katibah (1984) estimates that 92 percent to 95
percent of the Central Valley’s riparian habitat has been lost. Riparian
habitat on the Kern Refuge represents four percent to five percent of the
land area and less than one percent on the Pixley Refuge. Uplands are
in noncontiguous blocks surrounded by agriculture. From 1976 to 1980,
70 percent of habitat used by the endangered blunt-nosed leopard lizard
had been lost to urbanization and agriculture (CDFG 2001). Other
endangered species dependent on upland habitat such as the San
Joaquin kit fox and Tipton kangaroo rat, have suffered similar losses.
Range contraction, lack of upland habitat corridors, and competition with
introduced species continue to adversely affect these animals.
Today, the Refuges represent some of the largest blocks of contiguous
uplands (Pixley Refuge) and managed wetlands (Kern Refuge) in the
southern Valley. Resident, migratory, and threatened and endangered
species as well as native plants continue to use these lands throughout
the year. While some of these species are found on and use private
property, their last stronghold in the southern Valley may be the
Refuges.
Soils
Kern Refuge
The five general soil types that have been mapped on the Kern Refuge
include: Nahrub, partially drained-lethent complex (3,540 acres);
Nahrub, drained-lethent complex (2,760 acres); Nahrub clay, drained
(1,830 acres); Nahrub clay, partially drained (1,510 acres); and Garces
silt loam (60 acres). When these soil types were mapped in 1982, 870
acres of the Refuge were flooded, and therefore not mapped. The
Nahrub and Lethent soils formed in alluvium from primarily granitic
and sedimentary rock. Nahrub soils occur as deep deposits (depths to 61
inches), with little to no surface slope, and poor drainage. They are
composed of an upper layer of clay (0 to 34 inches) overlaying a lower
layer of sandy loam, clay loam, and fine sandy loam. Lethent soils are
also deep but are moderately well drained and are composed of a surface
layer of silt loam (0 to 6 inches) over a clay layer up to 36 inches thick
supported by loam to depths greater than 60 inches. Nahrub and
Lethent soils are moderately to strongly saline-alkaline and may have
Chapter 3
24 Kern and Pixley National Wildlife Refuges
Figure 7. Regional Land Cover
Refuge and Resource Descriptions
Comprehensive Conservation Plan 25
toxic levels of boron present in some areas. Permeability is very slow
and water capacity is low. A seasonally high water table limits rooting
depth to three to six feet in Nahrub soils; however, rooting depths in
Lethent soils are greater than five feet.
Garces silt loam is a deep (60 inches and greater) well-drained soil with
little to no slope formed in alluvium derived from granitic rock. This soil
is moderately to strongly saline-alkaline and may have toxic levels of
boron present in some areas. While permeability is slow, rooting depths
of greater than five feet are common.
Suitability of the Nahrub-Lethent and Garces soils for farming and
grazing is poor to marginal. Farming is limited by slow to very slow
permeability, clay textures, perched water table, and saline-alkaline
conditions. These conditions, as well as annual rainfall, limit grazing.
Only the Nahrub clay, partially drained and Garces soils are identified as
soil types capable of supporting grazing within local rainfall and saline-alkaline
constraints.
The characteristics and constraints of the soil types found on Kern
Refuge indicate that new roads, levees and wetland units should not be
developed from local soils. Periodic maintenance on roads and levees
that support the auto tour route and regular Kern Refuge operations,
incorporate suitable base material and surface aggregate from off-site.
Less used interior roads and levees developed from on-site materials are
occasionally impassable, especially during the wet winter months.
The soil types on the Kern Refuge have little effect on wetland
management. Some shallower moist soil units are periodically farmed or
subject to regular maintenance (disc, mow, burn, etc.) to manage wetland
vegetation growth. Larger and deeper seasonal wetlands are not farmed
but selected areas of vegetation are periodically managed to maintain
and enhance open water habitat. During draw down and dry out of
wetlands, the characteristics of local clay soils are evident. The
saturated and sticky clay soils prohibit access into the wetlands by heavy
equipment until the soils are almost completely dry. Earlier dewatering
of some units is conducted so that there will be a dry enough substrate
for maintenance.
None of the lands within Kern Refuge’s approved boundary are
designated Prime Farmland or Farmland of Statewide Importance by
the California Department of Conservation.
Pixley Refuge
The eleven soils types that have been mapped within Pixley Refuge’s
approved boundary include: Akers-Akers, Saline-Sodic Complex (18.3
acres); Biggriz-Biggriz, Saline-Sodic Complex (101 acres); Gambogy
loam (469 acres); Gambogy-Biggriz, Saline-Sodic Association (4,157
acres); Gareck-Garces Association (2,101 acres); Hanford sandy loam
(less than 1 acre); Houser silty clay (15 acres); Kimberlina fine sandy
loam (580 acres); Lethent silt loam (2,193 acres); Nahrub silt loam (74
acres); and Riverwash (less than 1 acre). All of these soils are alluvium
Chapter 3
26 Kern and Pixley National Wildlife Refuges
derived mainly from granitic rock sources located in former fan terraces,
alluvial fans, flood plains, and basin rims.
With the exception of 300 to 600 acres of created wetlands that include
levees and roads on Lethent silt loam within Pixley Refuge boundary, all
of the other soil types have not been significantly disturbed. Less
frequently used dirt roads occur along the boundaries and are used for
periodic surveys and fence maintenance. The majority of the other soil
types support introduced grasses. Grazing occurs on about 4,730 acres
of Pixley Refuge to provide more suitable habitat for listed species and
to promote the establishment and growth of native vegetation. No new
development is planned for the Pixley Refuge, but periodic maintenance
of the roads and wetlands is required.
More than 1,000 acres of land within the approved boundary have been
leveled and reclaimed for irrigated croplands. Regular soil amendments
are required to maintain productivity of cultivated crops. While Houser
silty clay, Kimberlina fine sandy loam, Lethent silty loam, Nahrub silt
loam, and Riverwash are not considered prime farmland, these soil
types, with the exception of Riverwash, are farmed. However, about 340
acres are considered Farmland of Statewide Importance by the
California Department of Conservation. The Department of
Conservation defines Farmland of Statewide Importance as irrigated
land similar to Prime Farmland that has a good combination of physical
and chemical characteristics for the production of agricultural crops.
This land has minor shortcomings, such as greater slopes or less ability
to store soil moisture than Prime Farmland. Land must have been used
for production of irrigated crops at some time during the four years prior
to the mapping date.
Water
Kern Refuge
Historic Environment. Historically, the land area now managed as the
Kern Refuge was at the extreme southern portion of Tulare Lake. The
present-day location of Kern Refuge and the extent of the historic lake
basin suggest that during wet years, areas of Kern Refuge may have
been flooded by rising lake waters. Additionally, areas of Kern Refuge
likely supported emergent wetland vegetation and riparian habitat that
connected streams originating to the east in the Sierra Nevada
Mountains with the historic Tulare Lake Basin in the Valley.
Conversion of the southern Valley from natural lands to agriculture
beginning in the late 1800s resulted in the loss of wetlands and increased
management of rivers to control floods and provide irrigation water to
farmers. During this time, low dikes and canals were constructed for
agricultural purposes on the land now occupied by the Kern Refuge and
construction of the Goose Lake Canal, the major waterway that bisects
the Refuge into eastern and western halves, was completed. With an
average annual rainfall of six inches, the loss of natural wetlands,
decreased frequency of spring floods, and a highly managed water
delivery system of canals and dikes, the wetland dynamics of the
Refuge and Resource Descriptions
Comprehensive Conservation Plan 27
southern Valley of today bears little resemblance to that of less than 100
years ago.
Refuge Water Development and Management. When development of
the Kern Refuge began in the early 1960s, ten wells were drilled
throughout the Refuge to provide a source of water for wetland
management purposes. These wells averaged slightly in excess of 800
feet deep and were able to provide a limited source of water at a rate of
approximately 1,600 gallons per minute. This production rate did not
meet the needs of the Refuge’s habitat and electrical costs prohibited the
Service from using this groundwater as a sole source for habitat
management.
Currently, three of the wells are still operable with water levels
stabilized approximately 200 feet below the surface. Water quality is
relatively good with the exception of boron and arsenic levels that are
consistently high in all wells. Slightly below the ground surface and
located above an impervious clay layer is a perched or suspended aquifer
or layer of water that is highly saline and not suitable for irrigation or
habitat purposes. In some locations around the Refuge, this perched
aquifer is less than 5 feet below the surface.
Because using the wells proved to be cost prohibitive, the Service began
purchasing fall and spring irrigation water from local water districts
when available. In years of normal rainfall and when budgets permitted,
sufficient water was purchased to flood less than 2,500 acres of fall and
winter habitat at a cost exceeding $240,000. In years of limited water
availability, less than 1,200 acres were flooded and this habitat was not
available until late in the fall or early winter, far too late for the early fall
migrant ducks that use the area.
The Central Valley Project Improvement Act, Title 34 of Public Law
102-575, was passed by Congress on October 30, 1992. A major purpose
of the CVPIA was to change the management of the Central Valley
Project to make fish, wildlife, and associated habitat protection and
restoration a project purpose equivalent to that of supplying water and
power for municipal and agricultural purposes. The CVPIA identified
wetlands as a key component of wildlife protection and enhancement in
the Central Valley and specified actions to further assess water needs
and supply opportunities. Under provisions of the CVPIA, Kern Refuge
was provided an annual allocation of 25,000 acre-feet of water for
wetland management purposes.
Only since implementing the Central Valley Project Improvement Act of
1992 (CVPIA) has the amount of water delivered to the Kern Refuge
been consistent and of sufficient volume to provide adequate wetland
habitat for migratory waterfowl and waterbirds. With this water, the
Refuge is able to flood 3,000 to 6,400 acres sequentially over a 3 to 5
month period beginning in mid-August. Normally all CVPIA water
destined for the Refuge is released from the California Aqueduct into the
Buena Vista Water Storage District system and transported nearly 12
miles through the Buena Vista Water Storage District Main Drain canal
to the Refuge boundary.
Chapter 3
28 Kern and Pixley National Wildlife Refuges
The CVPIA water is divided into two categories, Level 2 supplies sustain
the historic level of habitat produced annually on the Kern Refuge, and
Level 4 supplies provide sufficient water to reach optimum development
of all potential wetland habitat on the Refuge. The CVPIA allocated a
total of 9,950 acre-feet of Level 2 water and 15,050 acre-feet of Level 4
water for developing and maintaining 6,700 acres of wetland habitat on
an annual basis. Once water has been delivered into unit 1 of the Refuge,
the water will be distributed throughout the moist soil units on the
Refuge via a lift pump structure and a series of distribution ditches.
Throughout the balance of the Refuge’s seasonal wetlands, water will be
distributed on a gravity flow basis through a system of pipes and gates
that control these flows.
Early fall flood-up of Refuge habitat coincides with the late irrigations of
agricultural crops upstream from the Refuge along the Main
Drain/Goose Lake Canal. During this period, the Refuge water supply is
heavily affected by irrigation return flows into the system. Water
quality analysis during this period has shown no significant levels of
pesticides, heavy metals, or other contaminants that could be
detrimental to Refuge wildlife or habitat. However, high levels of
dissolved salts have been documented. By mid-November, these
agricultural return flows have ceased and water quality has greatly
improved.
Flooding. In 1961, while searching for an adequate water supply for the
Kern Refuge, the Service considered accepting floodwater from Poso
Creek that originates in the southern Sierra Nevada Mountains. In 1962
and 1963, the Poso Creek channel was realigned and improved to handle
1,000 cubic feet per second of floodwater and extended to reach the
southeast corner of the Refuge. No legal provisions were made to
dispose of floodwater in excess of the holding capacity of the Refuge at
any given time. Major floods originating from the Poso Creek watershed
occur approximately every 10 to 12 years during which total discharges
may exceed 130,000 acre-feet of water. Smaller floods generating in
excess of 35,000 acre-feet of floodwater occur every four to five years.
Floods that reach the Refuge generally occur during the January
through March period, the same time the Refuge has reached its
maximum habitat management levels, thus limiting the amount of
available floodwater storage capacity.
Because the Refuge is not on any natural watercourse, the Service has
no discharge point that does not interfere with neighboring landowners.
To release any water from the Refuge, prior approval from downstream
users on Goose Lake Canal must be obtained. This is not an option
during floods since other rivers and streams are usually in flood stage as
well and the Poso Creek water would be an additional burden.
Refuge and Resource Descriptions
Comprehensive Conservation Plan 29
Aerial View of Kern Refuge Facing Southwest During 1986 Flood. U.S. Fish & Wildlife Service Photo.
Normal management practices for seasonal wetlands require that every
unit be dewatered each spring to permit the growth of annual food
plants. To facilitate the draining of Refuge impoundments water must
be released from units 7 and 8 to provide space for other units to the
south to be drained. In the past, this drain water has been given to
adjacent landowners for use as irrigation water or to help create habitat
on private wetlands.
Pixley Refuge
Situated within the historic flood plain of Deer Creek, the area now
managed as the Pixley Refuge was on the eastern edge of Tulare Lake.
While the far west portion of the Turkey Tract may have been a part of
the actual wetlands of the lake, the majority of the remaining land area
probably consisted of riparian habitat, seasonally flooded wetlands,
vernal pools, and wet meadows, depending on the level of precipitation in
any given year.
Although more than 750 acres of Pixley Refuge are designated to be
managed as wetlands, sufficient water has not been available to provide
any significant marsh habitat on a reliable basis. Infrequent flood flows
in Deer Creek have at times been diverted into the Refuge wetlands to
provide habitat on a very limited basis. In addition, in years of sufficient
runoff when excess irrigation water is present, the Pixley Irrigation
District has used some of the wetland units for groundwater recharge,
providing habitat for water birds as a secondary benefit. While this
habitat has been beneficial, this recharge water usually occurs in late
spring and early summer, which is too late for the fall and winter
migrant species to use the area.
With the passage of the CVPIA, the Pixley Refuge was provided an
annual water allocation of 6,000 acre-feet including 1,280 acre-feet of
Level 2 water and 4,720 acre-feet of Level 4 water. This allocation was
Chapter 3
30 Kern and Pixley National Wildlife Refuges
intended to be sufficient to allow the development and maintenance of
755 acres of seasonal wetlands including 25 acres of riparian habitat, and
545 acres of irrigated pastures and croplands to be used primarily by
lesser and greater sandhill cranes. While the designated source for the
Refuge’s CVPIA water allocation was the Friant-Kern Canal, no suitable
canals or pipelines currently connect the Refuge to the water source.
As an interim measure to provide the Pixley Refuge with water while a
delivery system can be developed, a deep well was drilled in 1994 as a
joint project with Ducks Unlimited. With the water from this well, which
is just west of County Road 88, east of the Pixley Refuge wetland units,
the Pixley Refuge can develop and maintain approximately 300 acres of
seasonal wetlands. Various alternatives have been considered for a
permanent delivery conduit for a Friant-Kern water supply but the most
promising is to use existing pipeline systems from the Friant-Kern Canal
to a point west of Highway 99 and then construct a new line from there
to the Refuge wetlands. It may be necessary to drill a second well on the
Refuge as part of a conjunctive use program that will permit the
combined use of wells and delivered surface water to meet the water
needs of the Refuge. When the final delivery system is in place, total
wetlands will exceed 750 acres, more than twice the current flooded
acreage.
Air Quality
The Refuges are in California’s San Joaquin Valley Air Basin. Air
quality in the Valley is among the worst in the United States. The San
Joaquin Valley Unified Air Pollution Control District is the agency
responsible for ensuring compliance with Federal and State air quality
standards in the Valley. The Federal and State governments have each
established ambient air quality standards for several pollutants. Most
standards have been set to protect public health. However, standards
for some pollutants are based on other values such as protecting crops
and materials and avoiding nuisance conditions. Currently, the Valley is
federally classified as a serious nonattainment area for both ground-level
ozone and particulate matter less than 10 microns in diameter (PM10).
In addition, the Valley is classified as a severe nonattainment area for
the California ozone standard and nonattainment for the PM10 standard.
The Valley is in attainment or has not been classified for all other criteria
pollutants.
Ozone, the main component of photochemical smog, is formed through a
complex series of chemical reactions between reactive organic gasses
(ROG) and nitrogen oxides (NOx). On-road motor vehicles are the
largest contributors to NOx emissions in the Valley. On-road motor
vehicles, area-wide sources, and stationary sources are significant
contributors to ROG emissions. A significant portion of the stationary
source ROG emissions are fugitive emissions from the extensive oil and
gas production operations in the southern Valley. Once formed, ozone
remains in the atmosphere for one or two days. As a result, ozone is a
regional pollutant and often affects a large area. Ozone’s main effects
include damage to vegetation, chemical deterioration of various
materials, and irritation and damage to the human respiratory system.
Refuge and Resource Descriptions
Comprehensive Conservation Plan 31
Carbon monoxide (CO) is a odorless, invisible gas which usually forms as
a by-product of incomplete combustion of organic substances. The
majority of the CO emitted in the Valley comes from motor vehicles.
Carbon monoxide is a relatively localized pollutant, often resulting from
a combination of high traffic volumes and traffic congestion. As a result,
measured concentrations are not necessarily representative of the entire
study area. A mildly toxic pollutant, CO interferes with oxygen
transport to body tissues.
Airborne dust (PM10) is produced by stationary point sources such as:
fuel combustion and industrial processes; fugitive sources, such as
roadway dust from paved and unpaved roads; wind erosion from open
land; and transportation sources, such as automobiles. The primary
sources of PM10 in the Valley are fugitive dust from paved and unpaved
roads and agricultural operations. Soil type and soil moisture content
are important factors in PM10 emissions. Federal and State PM10
standards are designed to prevent respiratory disease and protect
visibility.
Certain land uses are considered more sensitive to air pollution than
others. Locations such as schools, hospitals, and convalescent homes are
labeled sensitive receptors because their occupants (the young, old, and
infirm) are more susceptible to respiratory infections and other air
quality-related health problems than the general public. Residential
areas are also considered sensitive receptors because residents tend to
be home for extended periods, resulting in sustained exposure to any
pollutants present. Sensitive receptors in the study area include the
Refuge Complex headquarters and residences at Kern Refuge and the
few scattered private residences south and east of Pixley Refuge.
Plant Communities
Kern Refuge
The Kern Refuge supports a variety of wetland and upland vegetation
over the 10,618 acres managed for waterfowl and endangered species.
The 1986 Master Plan identified six major vegetative communities
(marsh/seasonal wetland, alkali playa, valley grassland, cultivated
cropland, alkali scrub, and riparian) with 16 subcategories. At that time,
wetland acreage was based on the amount of wetland habitat that was
normally flooded from 1977 to 1984. From this information, wetland
habitat accounted for approximately 37 percent (3,850 acres) of the total
land area on the Refuge.
In recent years, the quantity and availability of water has increased,
allowing the Kern Refuge to provide more wetland habitat. As part of
the CCP process, a new vegetation map was completed that more
accurately reflects current conditions on the Refuge. Vegetation types
were delineated based on recent aerial photographs, global positioning
system (GPS) data taken in the field, and additional ground truthing.
Chapter 3
32 Kern and Pixley National Wildlife Refuges
Based on this information, eight plant communities have been identified
including grassland, seasonal marsh, alkali playa, grassland/alkali playa,
moist soil wetland, riparian, valley sink scrub, and salt cedar (Figure 8).
The salt cedar plant community covers approximately 1,600 acres and is
in former wetland and grassland habitat types. Wetland habitat covers
approximately 5,300 acres and includes 3,800 acres of seasonal marsh,
1,200 acres of moist soil wetlands, and 215 acres of riparian habitat. An
additional 1,200 acres of moist soil wetlands are being restored.
Salt cedar is most commonly found on the west side of the Kern Refuge
in dense impenetrable stands. Stands on the east side occur in seasonal
wetlands and along the levees of some wetland units. On both sides of
the Refuge, this habitat type has replaced grassland and wetland habitat.
The Service is actively using mechanical and chemical control methods in
an effort to control and remove this invasive species to restore wetland
and grassland habitats.
All plant community names are from Terrestrial Natural Communities of
California (Holland 1986). Exceptions include moist soil wetlands and
agricultural croplands. Appendix E includes a list of plant species
documented on the Refuge.
Wetland Plant Communities. Wetland plant communities occur in
seasonal marshes, moist soil wetlands, and in riparian habitat. Salt cedar
habitat occurs in these three wetland habitat types.
Seasonal Marsh. Units 1, 1A, 2, 2A, 3, 6B, 6C, 7, and 8 are designated
seasonal marshes and cover approximately 3,800 acres. They are large
(156 to 846 acres) units characterized by water depths less than 4 feet
and robust perennial wetland vegetation. Even though these units are
Seasonal Marsh Habitat at Kern Refuge. U.S. Fish & Wildlife Service Photo.
Refuge and Resource Descriptions
Comprehensive Conservation Plan 33
Figure 8. Land Cover: Kern Refuge
Chapter 3
34 Kern and Pixley National Wildlife Refuges
seasonally flooded only from September to May or June, adequate soil
moisture throughout the dry and hot summer months provides suitable
conditions for growing and maintaining cattail and hardstem bulrush.
While cattail and hardstem bulrush may dominate certain areas of some
seasonal marshes, other wetland plants are also common and include
alkali bulrush and spike-rush. In deeper areas, burrhead and arrowhead
are common, especially along the edges of ditches. Woody vegetation
within these marshes can occur as isolated trees and shrubs of salt cedar,
willow, and cottonwood or in dense thickets (salt cedar). Patches of
iodine bush and alkali heath occur in slightly higher areas within the
units. Selected areas may be occasionally mowed, disked, or burned to
control perennial vegetation and maintain open water habitat.
Moist Soil Wetlands. Units 4, 5, 6A, and 14 are designated moist soil
wetlands and include about 2,400 acres. These wetlands are also
seasonally flooded, small (22 to 62 acres), and are characterized by water
depths less than 8 inches in the fall and winter and less than 2 inches in
spring. These units are intensely managed by the Service through
mowing, disking, and burning to maximize waterfowl food plant
production. In any given year, approximately 20 percent of the total
moist soil wetland acreage is subject to some form of vegetation
management. These management actions are to promote the growth of
swamp timothy and water grass while curtailing the spread of alkali
bulrush and isolated stands of cattail and hardstem bulrush. Other
species existing in these units include sprangle-top and various species of
rushes. Swamp timothy exists naturally and requires one or two
irrigations in the late spring or early summer while water grass is
directly cultivated in prepared units and irrigated as needed.
Riparian Habitat. Unit 9 and the southern portion of unit 10 contain the
largest tract (215 acres) of riparian habitat on the Kern Refuge. The
riparian habitat on the Refuge is contiguous with riparian habitat
Riparian Habitat on Kern Refuge. U.S. Fish & Wildlife Service Photo.
Refuge and Resource Descriptions
Comprehensive Conservation Plan 35
immediately south of the Refuge on private property. Viewed from
above, a series of old channels associated with the Kern River meander
through this area from south to north. Water is managed in these units
to maintain and promote this habitat type on the Refuge but there is no
outlet. Cottonwood and willow trees dominate but salt cedar is common
in some areas. Smartweed is common in the channels.
Alkali Playa. Easily distinguishable mostly bare, alkali soils. The most
common plants associated with alkali playas are annual Atriplex species
and annual grasses.
Upland Plant Communities. Upland plant communities occur in
grasslands, alkali playas, grassland/alkali playa complex, and valley sink
scrub. Salt cedar habitat exists in the following four upland habitat
types.
Grasslands. This habitat type covers approximately 2,800 acres on the
west side of the Kern Refuge occurring from the southern to northern
boundaries. Depending on the soil type and elevation, grassland plants
are associated with clay and sandy soils, and where the elevation is
slightly lower, with vernal pools. Common vernal pool plants include
coyote-thistle, Fremont’s goldfields, and short woollyheads. These
plants can be found in or near vernal pools were shallow pools and
meandering sloughs collect moisture from winter rains. Both sandy and
clay soil grassland plants may occur as either dense or sparse
associations of brome, barley, annual fescue, California poppy, cream
cups, bird’s eye gilia, spikeweed, and goldfields. Nonnative grasses
(bromes and fescues) can become dense over a considerable area and
encroach into areas supporting mainly native grasses as well as decrease
the overall suitability of grassland habitat for threatened and
endangered species. As a result, grazing is used to control nonnative
grasses and to provide more open habitat suitable to the endangered
blunt-nosed leopard lizard and Tipton kangaroo rat.
Grassland/Alkali Playa Complex. This community consisted of areas
where alkali playa and grassland habitats were interspersed and could
not be delineated. Cumulatively, the alkali playa and the grassland/alkali
playa complex covers approximately 500 acres on the Kern Refuge.
Valley Sink Scrub. This habitat type occurs mainly on the west side, but
small patches occur in higher areas in seasonal wetlands on the east side.
Approximately 750 acres of this habitat type occur on the Kern Refuge
and may be dominated by either saltbush or iodine bush. Saltbush-dominated
areas are sparsely vegetated and may also include aster.
Plants in iodine bush–dominated communities are mostly succulent and
occur on alkaline or poorly drained soils. Common plants in this
community are iodine bush, suaeda, and alkali heath.
Pixley Refuge
Eight major land cover categories are found within the Pixley Refuge
approved boundary: California annual grassland, alkali playa, northern
Chapter 3
36 Kern and Pixley National Wildlife Refuges
claypan vernal pool, valley saltbush scrub, riparian, Great Valley willow
scrub, intensively managed moist soil units, and agricultural croplands.
About 74 percent of the lands within the approved boundary are annual
grassland. Of the wetland plant communities, managed moist soil
communities cover the greatest area. Figure 9 shows the distribution of
plant communities within the approved refuge boundary. Below is a
description of each plant community, including plant composition,
ecological relationships, and distribution on the Refuge.
Wetland Plant Communities.
Moist Soil Wetlands. All the 756 acres of managed wetlands on the
Pixley Refuge are designated moist soil wetlands. These small wetlands
are seasonally flooded and characterized by water depths of less than
eight inches in the fall and winter and less than two inches in the spring.
These units are occasionally managed by the Refuge through mowing,
disking, and burning to maximize waterfowl food plant production. In
any given year, less than 20 percent of the total moist soil wetland
acreage is subject to some form of vegetation or soil management. These
management actions are to promote the growth of swamp timothy and
water grass while curtailing the spread of alkali bulrush and isolated
stands of cattail and hardstem bulrush. Other species occurring in these
units include sprangle-top and various species of rushes. Swamp timothy
exists naturally and requires one or two irrigations in the late
spring/early summer while water grass is directly cultivated in prepared
units and irrigated as needed.
Riparian. This habitat type is limited (about 15 acres) and occurs in a
narrow band along Deer Creek on the southern border of the Pixley
Refuge. Scattered cottonwood and willow trees are found along this
creek.
Alkali Playa. This community occupies about 39 acres, or less than 1
percent, of Pixley Refuge. However, these figures are an underestimate,
because only the larger alkali playas were mapped. About 1,300 acres of
the area mapped as annual grassland contain numerous small playas
interspersed throughout. This community occurs on poorly drained soils
with high salinity and/or alkalinity due to water evaporation that
accumulates in closed drainages. Typically, vegetative cover in this
community is 70 percent or less and the soil has a white salt crust.
Indicator species of this community include alkali plagiobothrys, salt
sand-spurry, low barley, Mediterranean grass, and alkali weed (Trask
1989).
Northern Claypan Vernal Pool. Northern claypan vernal pools are
shallow depressions lined with an impervious clay layer that temporarily
fill with water during the winter and spring rains and dry out completely
during the summer. Water stands in the pool during the early part of
the growing season, preventing most grassland species from becoming
established. However, several annual plant species are specially adapted
to this unique environment. Plants commonly found in vernal pools at
Pixley Refuge include goldfields, popcorn flower, coyote thistle,
mousetail, pillwort, woolly heads, pygmy-weed, and flowering quillwort.
Refuge and Resource Descriptions
Comprehensive Conservation Plan 37
Figure 9. Land Cover: Pixley Refuge
Chapter 3
38 Kern and Pixley National Wildlife Refuges
Vernal Pool at Pixley Refuge. U.S. Fish & Wildlife Service Photo.
On Pixley Refuge, vernal pools are found only on the Two Well Tract and
the Big Deer Creek Unit and total about 36 acres.
Upland Plant Communities.
California Annual Grassland. Approximately 7,347 acres, or 74 percent,
of the lands within the approved Pixley Refuge boundary are California
annual grassland. This grassland is a mosaic of grassland and alkali
playas with vernal pools scattered throughout. The grasslands on Pixley
Refuge are typically dominated by nonnative annual grasses including
foxtail barley, low barley, soft chess, and red brome. Common forbs in
this community include red-stemmed filaree, California burclover, bush
seepweed, common spikeweed, bird’s eye gilia, and alkali heath. Alkali
goldenbush (a shrub) is also occasionally found in the grasslands. Soil
type has an important influence on the composition and structure of the
grassland community. In general, grassland plants growing on fine
textured soils are less dense and smaller than those growing on coarse
textered soils. The grasslands along Deer Creek have more coarse
textured soils and probably receive some subsurface moisture. Clumps
of the perennial grass alkali sacaton are common in this area (Trask
1989).
When rainfall is sufficient, cattle are grazed on the grasslands to reduce
cover and improve habitat conditions for the blunt-nosed leopard lizard
and Tipton kangaroo rat. All of Pixley Refuge uplands are grazed except
a 20-foot by 20-foot exclosure constructed in 1975 in the southwestern
corner of Section 23.
Valley Saltbush Scrub. This community is found in the 246-acre area
just east of the managed wetland units and was set aside as mitigation
for the development of the wetlands. Dominant shrubs in this
community include saltbush, iodine bush, and suaeda. The understory is
Refuge and Resource Descriptions
Comprehensive Conservation Plan 39
composed primarily of the same nonnative annual grass and forb species
found in the annual grasslands.
Agricultural Croplands. About 1,058 acres of private land within the
approved Pixley Refuge acquisition boundary are actively farmed to
provide feed for several dairies adjacent to the Refuge. These lands are
subject to intensive farming (discing, soil amendments, irrigating, and
harvesting) to support alfalfa and grain production.
Developed Areas. A number of dairies have developed within the
approved acquisition boundary since Pixley Refuge was established.
These dairies now occupy about 704 acres within the approved boundary.
Wildlife
The variety of unique habitats at the Refuges support a diversity of
wildlife species. More than 359 species of birds, mammals, amphibians,
and reptiles have been documented on the Refuges. Some 15 special-status
wildlife species are known or believed to use the Refuges.
Appendix E contains a list of wildlife species observed in the Refuges.
Birds.
Kern Refuge. A total of 214 bird species have been sighted on Kern
Refuge. Fifty-nine different species have nested on the Refuge. Species
recorded on the Refuge include waterbirds, such as northern pintails,
green-winged teal, and northern shoveler, which account for the largest
number of ducks wintering on the Refuge. Other species including
mallards, American wigeon, gadwall, cinnamon teal, canvasbacks,
redheads, lesser scaups, ring-necked ducks, buffleheads, and ruddy
ducks; and Canada geese, white-fronted geese, white pelicans, double-crested
cormorants, belted kingfishers, egrets, herons, American and
least bitterns, grebes, rails, gulls, terns, plovers, black-necked stilts,
Avocet Chick. U.S. Fish & Wildlife Service Photo.
Chapter 3
40 Kern and Pixley National Wildlife Refuges
American avocets, greater yellowlegs, western and least sandpipers,
dunlins, and long-billed dowitchers also use Kern Refuge.
Raptors, such as red-tailed hawks, northern harriers, Swainson’s hawks,
golden eagles, peregrine falcons, kestrels, barn owls, burrowing owls,
and great-horned owls, have been observed on Kern Refuge.
On Kern Refuge, west of Goose Lake Canal, there are about 2,600 acres
of upland communities consisting of annual grasslands and shrubs, such
as iodine bush, saltbush, and seepweed. These flats have also been
invaded by salt cedar. In some areas, small, sometimes-circular alkali
flats exist. These areas and some of the higher areas scattered
throughout the Refuge and along levees, provide habitat for birds
adapted to an upland existence including ring-necked pheasants,
mourning doves, and turkey vultures.
Other birds found in the uplands or in vegetation on the edges of
wetlands include hummingbirds, swallows, horned larks, flycatchers,
crows, ravens, and sparrows.
In the spring and fall a variety of neotropical migratory birds can be
found in the riparian areas of the Kern Refuge. Some of the species
include, common yellowthroats, western tanagers, warblers, vireos,
kinglets, thrushes, and cedar waxwings.
Red-winged, tricolored, and Brewer’s blackbirds use the marshes.
Pixley Refuge. Many of the same species that use Kern Refuge use
Pixley Refuge. Since Pixley Refuge consists primarily of the Valley
Grassland plant community type, mostly grassland bird species nest on
the Refuge. In recent years, beginning in August, ground water is
pumped to the surface to provide about 300 acres of moist-soil habitat
types. This provides habitat for migrating and wintering birds. Sandhill
cranes are the most prominent species that roost on Pixley Refuge
wetlands. Cranes begin arriving in September and numbers may peak at
up to 6,000 birds in January. Sixty-seven species of birds have been
documented using Pixley Refuge.
In the fall and winter, the wetlands also support many of the same
dabbling ducks found at Kern Refuge. In the past five years, green-winged
teal, northern shovelers, and mallards have been the three most
abundant ducks counted during mid-winter aerial surveys. Other
wintering waterfowl species abundant on the Refuge include gadwalls,
wigeons, and northern pintails. Wintering ducks may reach numbers as
high as 6,000 to 8,000 birds. Wintering Canada geese may number as
high as 600 birds and smaller flocks of white-fronted and snow geese
may be present.
Refuge and Resource Descriptions
Comprehensive Conservation Plan 41
Great Egrets. U.S. Fish & Wildlife Service Photo.
Pixley Refuge also provides wintering habitat for white-faced ibis. In
recent years, more than 2,000 white-faced ibis have been counted in a
single day roosting in the wetlands. Wintering and migrating shorebirds
also use the Refuge. Some of the more common shorebirds include:
black-necked stilts, yellowlegs, American avocets, killdeer, long-billed
dowitchers, and western and least sandpipers. Occasionally marbled
godwits and Wilson’s phalaropes are observed. In the uplands, long-billed
curlews are frequently sited in the winter, but mountain plovers
are rarely observed. Waterbirds that may be observed at the Refuge
include American coots, pied-billed grebes, various species of gulls, as
well as wading birds, such as great blue herons, black-crowned night
herons, great and snowy egrets, and American bitterns. Raptors
observed on the Refuge include red-tailed hawks, northern harriers,
American kestrels, burrowing owls, barn owls, and occasional sightings
of great horned owls, prairie falcons, peregrine falcons, black-shouldered
kites, turkey vultures, and Cooper’s hawks. Other common birds include
mourning doves, western meadow larks, horned larks, loggerhead
shrikes, and various species of sparrows and blackbirds.
Mammals
Kern Refuge. A total of 27 species of mammals have been sighted on
Kern Refuge. An additional 14 species may exist there based on their
regional distribution; however, sightings have not been confirmed. Some
of the mammals found on the Refuge include desert cottontail, black-tailed
jackrabbit, coyote, kit fox, bobcat, opossum, raccoon, muskrat,
beaver, badger, long-tailed weasel, striped and western spotted skunk,
California voles, Heermann’s kangaroo rat, Tipton kangaroo rat, deer
mouse, western harvest mouse, the San Joaquin pocket mouse, Botta’s
pocket gopher, house mouse, roof rat, the endangered Buena Vista Lake
shrew, California ground squirrel, and the San Joaquin antelope ground
squirrel. The Refuge may also be home to the broad-handed (California)
mole, although this is unconfirmed.
Chapter 3
42 Kern and Pixley National Wildlife Refuges
The Refuge is home to at least two flying mammals, the Mexican free-tailed
bat and the western mastiff bat. In addition, several other species
of bats may forage for insects on the Refuge including the western small-footed
myotis, California myotis, Yuma myotis, silver-haired bat,
western pipistrelle, big brown bat, hoary bat, western red bat,
Townsend’s western big-eared bat, and pallid bat.
Pixley Refuge. At least 16 species of mammals use Pixley Refuge as
habitat, and another 8 species may exist on the Refuge but their
presence has not yet been confirmed. Of the 16 mammals known to
inhabit Pixley Refuge, 5 are carnivores, such as coyotes, endangered San
Joaquin kit foxes, badgers, striped skunks, and long-tailed weasels.
Other species present include black-tailed jackrabbits, Audubon
cottontail (desert cottontail), California ground squirrel (Beechey ground
squirrel), Botta’s pocket gopher (valley pocket gopher), the endangered
Tipton kangaroo rat, Heermann’s kangaroo rat, deer mice, western
harvest mice, house mice, and, on rare occasions, in the water delivery
canals, muskrats. Species that may be on the Refuge but their presence
has not been confirmed include western mastiff bats, Mexican free-tailed
bats, ornate shrews, broad-handed (California) moles, raccoons, spotted
skunks, San Joaquin antelope ground squirrels, and California voles.
Reptiles and Amphibians
Kern Refuge. Kern Refuge is home to 12 species of reptiles and 4
species of amphibians.
The four species of lizards that inhabit Kern Refuge are the blunt-nosed
leopard lizard, an endangered species, the coast horned lizard, California
side-blotched lizard, and Western (California) whiptail.
Seven species of snakes have been recorded using the Refuge. One
species, the western (northern Pacific) rattlesnake is venomous. This pit
viper is commonly seen in the spring when temperatures begin rising.
The remaining species are the Pacific gopher snake, California (common)
kingsnake, western long-nosed snake, California glossy snake,
southwestern black-headed snake, and the common garter snake. An
eighth species, the coachwhip (San Joaquin whipsnake) (Masticophis
flagellum ruddocki) exists in the vicinity of the Refuge and possibly
exists on the Refuge but this has not been confirmed.
One western pond turtle was found on the Kern Refuge in the early
nineties, but that was a rare occurrence. The Service’s practice of
draining wetlands in the summer to prevent avian botulism probably
keeps the western pond turtle from being a permanent resident on the
Refuge. This species possibly could thrive here if fresh water was
available year around.
The amphibians found on Kern Refuge include the Pacific treefrog,
bullfrog, western toad, and western spadefoot toad.
Refuge and Resource Descriptions
Comprehensive Conservation Plan 43
Pixley Refuge. Pixley Refuge provides habitat for 13 species of reptiles
and amphibians and another 3 species of reptiles possibly exist on the
Refuge, but their presence has not yet been confirmed.
The four species of lizards inhabiting Pixley Refuge are the endangered
blunt-nosed lizard, coast horned lizard, California side-blotched lizard,
and western (California) whiptails. Western fence lizards may exist on
the Refuge but their presence has not yet been confirmed.
The five species of snakes present on the Refuge are the Pacific gopher
snake, California (common) kingsnake, western long-nosed snake,
southwestern black-headed snake, and, one poisonous species, the
western (northern Pacific) rattlesnake. The San Joaquin whipsnake
(coachwhip) and the California glossy snake possibly inhabit the Refuge
but confirmations have not been made for these two species.
Pacific Treefrog. U.S. Fish & Wildlife Service Photo.
The four species of amphibians that inhabit Pixley Refuge are the Pacific
treefrog, western (California) toad, western (Pacific) spadefoot toad, and
bullfrog.
Invertebrates
Kern Refuge. Even though aquatic invertebrates are no doubt
important as food for many species of wetland wildlife, there have been
no comprehensive invertebrate surveys conducted at Kern Refuge.
Some surveys are done on occasion by researchers looking for a
particular group of invertebrates. For example, when there is water on
the Refuge, the Kern Mosquito and Vector Control District monitors the
wet areas primarily for the seven species of mosquitoes that exist on the
Refuge (Culex erythrothorax, C. pipiens, C. tarsalis, Orahlerdatus
dorsalis, O. melanimon, O. nigromaculis, and Aedes vexans). In a study
of the feeding ecology of northern pintail and green-winged teal, Euliss
and Harris (1987) sampled the esophagial contents of numerous ducks
Chapter 3
44 Kern and Pixley National Wildlife Refuges
and found water fleas (Cladocera), seed shrimp, snails (Gastropoda),
dragonflies and damselflies (Odonata), midges, and flower flies
(Syrphidae). In another example, one researcher documented, for the
first time, a species of cattail bug found in the pistillate heads or spikes
of cattails growing on the Refuge.
During a 1997 limited survey for fairy shrimp, conducted in some of the
alkali pools in the northeastern part of unit 12, one species was found.
Comprehensive surveys of invertebrate and crustacean species and
learning more about their ecology are two areas that need further
development at the Refuge.
Pixley Refuge. There have been no comprehensive surveys for
invertebrates conducted at Pixley Refuge although aquatic invertebrates
are no doubt an important source of food for many species of wetland
wildlife.
During wet winters, several vernal pools collect and hold water. Three
species of fairy shrimp have been identified in some of these pools. They
include the versatile fairy shrimp, the alkali fairy shrimp, and the
Federally threatened vernal pool fairy shrimp. Also, clam shrimp have
been found in some of these pools but the species has not been identified.
Moth surveys conducted from 1993 to 1995 identified 55 species of moths
on the Refuge.
Special Status Species
The following section provides more information on special status species
that may exist or are known to exist on Kern or Pixley Refuges. This
includes species that are in the following categories: Federally listed and
proposed listed species; Bird Species of Conservation Concern at the
Regional (U.S. Fish and Wildlife Service Pacific Region) or more local
Bird Conservation Region (Coastal California Bird Conservation
Region1) scale; and State listed species. Birds identified by the Service
as species of conservation concern are predominantly nongame birds in
need of conservation action to prevent future listing as an endangered
species. Under Executive Order 13186 these species represent
conservation priorities for the Service, and other Federal agencies, and
are to be specifically considered during planning and when actions are
proposed on Federal lands.
San Joaquin Kit Fox
The San Joaquin kit fox (Vulpes macroti mutica) is a small fox with
relatively large ears and a long, bushy, black-tipped tail. They are
endemic to the Valley and surrounding foothills and a few interior coast
range watersheds. The San Joaquin kit fox is listed as a Federal and
State endangered species.
1 The Coastal California Bird Conservation Region includes the Central
Valley and California coast south of San Francisco Bay.
Refuge and Resource Descriptions
Comprehensive Conservation Plan 45
San Joaquin Kit Fox. U.S. Fish & Wildlife Service Photo.
The San Joaquin kit fox is commonly associated with valley sink scrub,
valley saltbush scrub, and annual grassland. Kit foxes also exist in some
highly modified landscapes including petroleum fields, urban areas, and
areas adjacent to agricultural fields. In general, they prefer to den in
loose-textured soils but can be found on nearly every soil type (Service
1998). The San Joaquin kit fox’s diet varies depending on abundance of
potential food sources. Nocturnal rodents such as kangaroo rats, pocket
mice, and white-footed mice comprise about one-third or more of their
diet. Kit foxes also feed on California ground squirrel, black-tailed
jackrabbit, San Joaquin antelope squirrel, desert cottontail, ground-nesting
birds, and insects (Service 1998). Home ranges of kit fox vary,
depending on prey abundance, from less than one square-mile up to
twelve square-miles (Service 1998).
The primary threats to the survival of this species are loss and
degradation of habitat by agricultural and industrial development and
urbanization.
Population numbers are low on the Refuge with only seven kit foxes
sighted on Kern Refuge during night spotlight surveys conducted from
1996 through 2000. Fifteen kit foxes were sighted on Pixley Refuge
during this same time. Resident or denning kit fox have not been
confirmed on Kern Refuge. Kit fox den sites were confirmed on Pixley
Refuge prior to the wet winters of the mid-1990s when their prey
population numbers crashed. Denning has not been confirmed since that
time. Occasionally, kit fox are found dead on the roads near both
Refuges.
Chapter 3
46 Kern and Pixley National Wildlife Refuges
Tipton Kangaroo Rat
The Tipton kangaroo rat (Dipodomys nitratoides nitratoides) is a small,
buff-colored rodent endemic to the southern Valley. This species is
listed as a Federal and State endangered species.
Tipton kangaroo rats inhabit arid-land communities such as iodine bush
shrubland, valley saltbush scrub, and annual grassland on the floor of the
Tulare Basin in level or nearly level terrain. Their habitat is typically
characterized by one or more species of sparsely scattered woody shrubs
and a ground cover of mostly introduced annual grasses and forbs.
Shrubs typically associated with Tipton kangaroo rats are: spiny and
common saltbushes, arrowscale, quailbush, iodine bush, pale-leaf
goldenbush, honey mesquite, and seepweed. Much of the low-lying
habitat occupied by Tipton kangaroo rats is susceptible to flooding from
winter rains and overbank flooding from creeks. Tipton kangaroo rats
commonly burrow in slightly elevated mounds, road berms, canal
embankments, railroad beds, and the bases of shrubs and trees where
windblown soils accumulate. The Tipton kangaroo rat’s diet consists
mostly of seeds with smaller amounts of green herbaceous vegetation
and insects (Service 1998).
Tipton Kangaroo Rat. U.S. Fish & Wildlife Service Photo.
In the past, the primary reason for the Tipton kangaroo rat’s decline was
habitat loss due to agricultural conversion. Today, the greatest threats
to this species are habitat destruction or modification from industrial and
agriculturally-related development, cultivation, buildup of heavy thatch
by nonnative annual grasses, and urbanization. Flooding also poses a
threat to this species (Service 1998).
Pixley Refuge provides some of the best remaining habitat for Tipton
kangaroo rats (Service 1998). The Endangered Species Recovery
Program has been studying the population ecology of Tipton kangaroo
rats at Pixley Refuge since 1992. Surveys are conducted on a grid in the
Deer Creek East Unit twice a year. Few or no animals have been
Refuge and Resource Descriptions
Comprehensive Conservation Plan 47
trapped in recent years. Population numbers crashed on Pixley Refuge
and other areas of the southern Valley in the mid-1990s when the areas
were flooded two winters in a row. Tipton kangaroo rats historically
occurred in the upland communities on the west side of Kern Refuge. All
of the west side was flooded in 1983 and partially flooded in the mid-
1990s. In limited, small mammal live-trapping surveys, conducted in
1992, 1993, 1994, and 1998, few Tipton kangaroo rats were captured on
the west side or near unit 8 on the east side.
Blunt-Nosed Leopard Lizard
The blunt-nosed leopard lizard (Gambelia sila) is a large lizard from the
iguana family with a long tail, long powerful hind limbs, and a short,
blunt snout. It is endemic to the Valley. The blunt-nosed leopard lizard
is listed as a Federal and State endangered species.
Blunt-nosed leopard lizards are found in open, sparsely vegetated areas
of low relief in the Valley and the surrounding foothills. In the Valley,
this species is most commonly associated with nonnative grassland and
valley sink scrub communities. Valley needlegrass grassland and alkali
playa also provide habitat for this species. In the foothills, the blunt-nosed
leopard lizard is found in saltbush scrub, upper Sonoran subshrub
scrub, and serpentine bunchgrass. They generally use small rodent
burrows for shelter from predators and temperature extremes (Service
1998). Blunt-nosed leopard lizards feed mostly on insects (primarily
grasshoppers, crickets, and moths) and other lizards (Service 1998).
Home ranges for this species vary from 0.25 acres to 2.7 acres for
females and from 0.52 acres to 4.2 acres for males (Service 1998).
Blunt-Nosed Leopard Lizard. US Fish and Wildlife Service Photo.
The primary threats to blunt-nosed leopard lizards are habitat
disturbance, destruction, and fragmentation. These threats come from a
variety of sources including development and operation of oil and gas
facilities, overgrazing, pesticide use, and on and off road vehicle use in or
near blunt-nosed leopard lizard habitat (Service 1998).
Chapter 3
48 Kern and Pixley National Wildlife Refuges
On Pixley Refuge, Uptain et al. (1985) found densities of blunt-nosed
leopard lizards ranging from 0.1 to 4.2 per acre. Biologists from
California State University, Stanislaus’s Endangered Species Recovery
Program have been monitoring population numbers in the Deer Creek
East Unit of Pixley Refuge from 1993 to the present. Population
numbers experienced a drastic decline in the mid-nineties when there
were successive years of high amounts of rainfall. On Pixley Refuge,
lizard abundances appeared to be greater in the year 2000 monitoring
season than they had been in recent years. On Kern Refuge, blunt-nosed
leopard lizard surveys of limited scope were conducted on the west side
in 1996 and 1998, with no blunt-nosed leopard lizards observed. The
most recent sighting was one lizard on the east side of Kern Refuge in
1994. Four sightings occurred in 1993, three lizards on the east side and
one in the San Joaquin Desert Research Natural Area (RNA) on the
west side.
San Joaquin Antelope Squirrel
The San Joaquin antelope squirrel (Ammospermophilus nelsoni) is a
small buff/tan colored ground squirrel with a light stripe on its side and a
light grey or white belly. This species is endemic to the Valley and the
Carrizo and Elkhorn Plains to the west. The San Joaquin antelope
squirrel is listed as a Federal species of concern and a State threatened
species.
The San Joaquin antelope squirrel inhabits arid annual grassland and
shrubland communities. This species is most abundant in areas with
sparse to moderate shrub cover (Service 1998). In the southern and
western Valley, San Joaquin antelope squirrels are associated with plant
communities containing saltbush and ephedra (Service 1998). They
rarely occur on alkaline soils or in areas that are subject to flooding. San
Joaquin antelope squirrels are omnivorous. They eat green vegetation,
fungi, insects, and to a lesser extent, seeds (Service 1998).
The greatest threat to the San Joaquin antelope squirrel is loss of
habitat to agricultural developments, urbanization, and petroleum
extraction. The long-term effects of overgrazing, namely loss of shrub
cover and soil erosion, may also threaten this species.
The San Joaquin antelope squirrel has not been seen on Kern Refuge for
many years. The last confirmed sighting on Pixley Refuge was in 1985.
San Joaquin antelope squirrels are more numerous south of Kern
Refuge in the Elk Hills area.
Buena Vista Lake Shrew
The Buena Vista Lake shrew (Sorex ornatus relictus) is a mouse-sized
mammal with a long snout and tiny bead-like eyes. The fur on its upper
surface is blackish-brown and the lower surface is smoke gray. Its tail is
bicolored and relatively short. Buena Vista Lake shrews were likely
historically distributed throughout the Tulare Basin (Service 2000). This
species is a Federally listed endangered species and a State species of
special concern.
Refuge and Resource Descriptions
Comprehensive Conservation Plan 49
Buena Vista Lake shrews prefer moist habitats with an abundant layer
of leaf litter. Plants typically found in their habitat include Fremont
cottonwood, willows, glasswort, alkali heath, wild rye grass, and Baltic
rush. The feeding and foraging habits of the Buena Vista Lake shrew
are not known. In general, shrews feed mostly on insects and other
invertebrates (Service 1998).
The primary reasons for the Buena Vista Lake shrew’s historical decline
and current threats to survival are loss and fragmentation of habitat. As
a result, this species faces a high risk of extinction from catastrophic
events such as floods and drought.
Three Buena Vista Lake shrews were found on the Kern Refuge in 1992
and 1994. Two Buena Vista Lake shrews were live-trapped and released
at the capture site in 1998 in the riparian area of Kern Refuge. In 1999,
Endangered Species Recovery Program biologists captured and
released five Buena Vista Lake shrews at the capture site along a
remnant slough in the moist-soil units of Kern Refuge.
In 2000, a limited survey resulted in no captures of Buena Vista Lake
shrews on Pixley Refuge on the southern boundary near Deer Creek.
Pixley Refuge has little potential habitat for shrews.
Mountain Plover
The mountain plover (Charadrius montanus) is a small, killdeer-sized
bird. Most mountain plovers winter in California’s Central Valley
(Sutter and Yuba Counties southward) from September through March.
Mountain plovers are also found in foothill valleys west of the San
Joaquin Valley, and in the Imperial Valley. This species is a California
Species of Concern. The mountain plover is also on the Service’s list of
Nongame Birds of Conservation Concern for the South Pacific Coast
Bird Conservation Region.
Mountain plovers in California winter in plant communities with short
vegetation, bare ground, and flat topography such as valley sink scrub,
alkali playa, and annual grassland (BLM 1992, Service 1999). Mountain
plovers are associated with areas grazed by domestic livestock, giant
kangaroo rat precincts, and California ground squirrel colonies. The
principle food of mountain plovers are beetles, grasshoppers, crickets,
and ants (Service 1999).
The principle threats to mountain plovers are conversion of grassland
habitat, agricultural practices in the breeding range, domestic livestock
grazing, and decline of native herbivores. Pesticide use in both the
wintering and breeding range may also be contributing to the decline of
this species.
According to Service records, from 1962 to 1967 mountain plover
numbers ranged from 1,000 to 10,000 on Kern Refuge. There have been
no recorded sightings of mountain plovers on Kern Refuge since 1985.
Mountain plover survey numbers have fluctuated at Pixley Refuge over
the years and the Refuge provide habitat for wintering birds although
Chapter 3
50 Kern and Pixley National Wildlife Refuges
population numbers fluctuate. In a 1993 survey, 109 plovers were
counted. In January 1994, 21 birds were counted. The last sighting
occurred in January 1997 when 15 birds were observed.
Tricolored Blackbird
The tricolored blackbird (Agelaius tricolor) is about the same size as the
more common red-winged blackbird and is similar in appearance. The
most obvious difference in males is that the bar above the red shoulder
patch is white on tricolors instead of yellow. This colonial nesting species
is most numerous in California’s Central Valley and vicinity. It also
occurs less commonly in coastal California, Oregon, and northwestern
Baja California (Beedy and Hamilton 1997). The Service classifies the
tricolored blackbird as a nongame bird of conservation concern at both
the Pacific Region and more local South Pacific Coast Bird Conservation
Region scale. The California Department of Fish and Game (CDFG)
classifies the tricolored blackbird as a species of special concern.
Tricolored Blackbird. U.S. Fish & Wildlife Service Photo.
Tricolored blackbirds have three requirements for colonial breeding
sites: (1) access to open water; (2) a protected nesting substrate (flooded
or thorny vegetation); and (3) suitable foraging habitat within about one
mile of the nesting colony (Beedy 1989, Beedy and Hamilton 1997).
Historically, tricolored blackbird breeding colonies occurred
predominately in freshwater marshes dominated by tules and cattails
(Beedy and Hamilton 1997). In recent years, an increasing percentage of
colonies are in Himalaya blackberries, and silage and grain fields (Beedy
and Hamilton 1997).
The primary threats to the tricolored blackbird are predation, inclement
weather conditions, habitat loss and alteration, poisoning, contaminants
and pollution, and human disturbance (Beedy and Hamilton 1997). At
Kern Refuge, the principle cause of nesting failure is predation by black-crowned
night herons (J. Allen pers. comm).
Refuge and Resource Descriptions
Comprehensive Conservation Plan 51
Tricolored blackbirds have attempted nesting on Kern Refuge every
year since 1992. Increased water supplies for wildlife mandated by
recent legislation permits the establishment of nesting habitat in most
years. Nesting flocks from 500 to 21,000 birds have been estimated over
the years. In the spring of 2000, a colony of approximately 5,000 birds
nested on the Refuge. Unfortunately, nesting success was low or
nonexistent, presumably due to black-crowned night heron predation,
another species that nests in the unit. In 2001, two colonies of tricolored
blackbirds nested on Kern Refuge in dense cattails with small amounts
of hardstem bulrush. The two colony sizes consisted of approximately
1,000 and 5,000 adult birds and it is believed they had some reproductive
success. The larger colony nested next to a colony of nesting white-faced
ibis.
Greater Sandhill Crane
Historically, when water is available, lesser and greater sandhill cranes
(Grus canadensis) roost on the wetlands of Pixley Refuge and feed in the
surrounding grazed and agricultural lands. In the winter of 2000/2001,
more than 5,000 sandhill cranes were roosting on the Refuge. The
shallow water of the Refuge gives roosting cranes protection from
ground predators such as coyotes. The subspecies composition is not
known but the majority of the birds using the Refuge are lesser sandhill
cranes. The greater sandhill crane is listed as a State threatened
species.
Vernal Pool Fairy Shrimp
The vernal pool fairy shrimp (Branchinecta lynchi) is a small (0.4 to 1-
inch long) crustacean with a delicate elongated body, large stalked
compound eyes and 11 pairs of swimming legs. This species is endemic
to vernal pool habitats in California and southwestern Oregon (Service
1994). The vernal pool fairy shrimp is federally listed as a threatened
species.
Vernal pool fairy shrimp typically inhabit vernal pools with clear to tea-colored
water, most commonly in grass or mud bottomed swales, or
basalt flow depression pools in unplowed grasslands. They also may
exist in alkaline vernal pools (Service 1994). The water in pools inhabited
by this species has low total dissolved solids (TDS), conductivity,
alkalinity, and chloride (Service 1994). Fairy shrimp feed on algae,
bacteria, protozoa, rotifers, and bits of detritus (Service 1994).
The primary threats to vernal pool fairy shrimp are the loss and
alteration of habitat due to urban and agricultural development and
random extinction by virtue of the small isolated nature of many of the
remaining populations (Service 1994).
The vernal pools found on the Pixley Refuge are not classic vernal pools
but may represent a transition zone from prominent vernal pools further
north in the Valley and no pools in the southern end. In 1993, vernal pool
fairy shrimp were found in vernal pools on the Two Well Unit (Engler
1993) of Pixley Refuge. The current status of this population is
unknown.
Chapter 3
52 Kern and Pixley National Wildlife Refuges
White-faced Ibis
White-faced ibis (Eudocimus albus) range from northern California,
eastern Oregon, southern Idaho, southern Alberta, Canada, Montana,
eastern North and South Dakota, and recently northwest Iowa south to
the states of Durango and Jalisco in Mexico (Ryder and Manry 1994).
Winter range is primarily in coastal Louisana and Texas south to Mexico
and Central America. In California, ibis winter in the San Joaquin
Valley, at the Salton Sea, and locally in southern California (Rosenberg
et al. 1991).
Ibis feed in the shallowly flooded pond margins or mudflats of the
Refuges. They fly off the roosting and nesting marshes at Kern Refuge
to feed in flood-irrigated agricultural fields. Their diet consists of
aquatic and moist-soil invertebrates, especially earthworms and larval
insects (mainly Orthoptera, Odonata, Hemiptera, Coleoptera, and
Diptera), but also leeches and snails. They may also eat crayfish, small
fish, frogs, bivalves, and larvae of chironomid flies (midges) (Ryder and
Manry 1994).
White-faced Ibis. Marguerite Gregory © California Academy of Sciences.
White-faced ibis population numbers increased on Kern and Pixley
Refuges in the 1990s, mainly due to higher water allocations for the
Refuge Complex. Higher water allocations, in times when droughts are
not occurring, permit wetlands to be created earlier in the summer as
water is delivered to the Refuges and remain longer in the spring as
Refuge and Resource Descriptions
Comprehensive Conservation Plan 53
there is more water available to maintain them. White-faced ibis
numbers have gone from zero in 1990 to more than 5,600 birds counted
on unit 1, the primary roosting area, in June 2001. Also, at least 1,000
ibis active nests were estimated to be in unit 1 in the spring of 2001.
Because nesting habitat is limited in the southern Valley, Kern Refuge is
important for reproducing birds.
The Pixley Refuge provides important foraging and roosting habitat for
the white-faced ibis. In early February 2001, more than 2,200 white-faced
ibis were counted at sunset coming into the 300-acre wetland of
Pixley Refuge to roost.
Bald Eagle
The bald eagle (Haliaeetus leucocephalus) has suffered from habitat
destruction and degradation, illegal shooting, and contamination of its
food source, most notably due to the pesticide DDT. The bald eagle is
listed federally as a threatened species and State listed as an endangered
species.
Bald eagles occasionally visit the Kern Refuge during the winter when
abundant waterfowl provide a food source. The most recent sighting on
the Refuge was in December of 2003.
American Peregrine Falcon
The American peregrine falcon (Falco peregrinus) was federally listed
as an endangered species in 1970, and State listed as endangered in 1971.
In August 1999, the American peregrine falcon was federally delisted.
The American peregrine falcon is seen occasionally on the Kern Refuge
especially during the winter when waterfowl populations are high and
provide a prey base. Single observations of peregrine falcons have been
reported in recent years primarily in the moist-soil units of Kern Refuge
in the winter and spring months. Willow trees in the moist-soil units and
a few utility poles provide perching sites for the falcons.
Swainson’s Hawk.
The Swainson’s hawk (Bueto swainsoni) is an uncommon breeding
resident and migrant in the Central Valley (Polite 2000b). Swainson’s
hawks breeding in California may spend the winter in Mexico and South
America. Central Valley hawks appear to winter in Mexico and
Columbia (CDFG 2001). Bloom (1980) estimated 110 nesting pairs, and a
total population of 375 pairs in California (Polite 2000b). The Swainson’s
hawk is State listed as a threatened species.
Declining numbers of Swainson’s hawks are caused, in part, from loss of
nesting habitat (Polite 2000b). Converting agricultural lands to various
residential and commercial developments is a serious threat to
Swainson’s hawks throughout California (CDFG 2001).
Swainson’s hawks are rare migrants at Kern Refuge and reportedly
breed further north. There are also records south of Kern Refuge on
Kern Waterbank lands. Most sightings for the Refuge occur in July and
Chapter 3
54 Kern and Pixley National Wildlife Refuges
August in the riparian area, with occasional sightings in March of a
single bird. In mid-August 1993, a prescribed burn on the west side of
the Refuge created good foraging habitat and 19 Swainson’s hawks were
recorded feeding there. One pair of Swainson’s hawks did breed in an
area north of the Refuge in 1993, and produced three young. Four
Swainson’s hawks were seen in the Refuge riparian area in 1999,
suggesting the Refuge provides limited roosting and foraging habitat as
the birds migrate to South America. The birds have not been observed
using the Refuge riparian area for nesting sites.
Swainson’s hawks have been observed in the vicinity of Kern Refuge in
migratory kettles. Kettles of Swainson’s hawks have been observed
hunting and roosting off Refuge in areas where sheep are grazing, in
newly cut alfalfa fields, and in burned areas. The largest kettle of
Swainson’s hawk’s on record contained 95 individuals and was seen in a
cut alfalfa field southeast of the Refuge along Wildwood Road in 1994.
Burrowing Owl
At one time, burrowing owls (Athene cunicularia) were common and
widespread over western North America. However, populations of owls
have declined, or disappeared altogether, due to the large scale changes
made to the owl’s habitat (Souza 1998) including: poisoning and nest site
loss resulting from human efforts to control squirrels and prairie dogs
(Ehrlich, et. al. 1988); and converting grassland to agriculture (Grinnell
and Miller 1944, Zarn 1974, and Remsen 1978). Burrowing owls are
listed as a Federal Species of Management Concern and a State Species
of Special Concern (Souza 1998).
Kern Refuge provides habitat for burrowing owls in the form of
grasslands on the west side along levees that contain abandoned
California ground squirrels burrows, and in the entrance tunnels of two
artificial kit fox dens. Small grassy areas such as the staging area north
of the Refuge’s headquarters building, and the mall in front of the
headquarters building, may support families of owls in some years.
Multiple surveys in the spring and early summer of 1993, yielded counts
of 12 distinct burrowing owl locations on Kern Refuge. On one sunrise
survey conducted in July 1999, on the east side of Goose Lake Canal on
Kern Refuge, five burrowing owls were counted. On night survey on the
Kern Refuge conducted along a 12.1-mile route on the west side of Goose
Lake Canal, five burrowing owls were counted in June of 1998.
Pixley Refuge, consisting of primarily grazed grasslands, provides more
habitat for burrowing owls. Multiple surveys conducted on Pixley
Refuge in the spring and early summer of 1993, yielded 20 burrowing
owl sites on Pixley Main (consisting of the Wetland, Centerfield, Two-
Well, Deer Creek West and Deer Creek East Units) and the Dickey
Tract. In addition, during this season, six burrowing owl locations were
recorded on Pixley’s Horse Pasture Unit.
On a sunrise survey of Pixley Main conducted on July 6, 1999, 48
burrowing owls were observed. On a sunrise survey of the Horse
Pasture Unit, conducted July 8, 1999, 28 burrowing owls were counted.
Refuge and Resource Descriptions
Comprehensive Conservation Plan 55
Later that morning, 45 burrowing owls were counted at the Los Feliz
Unit. On a 15.2-mile night survey route on Pixley Main, ten burrowing
owls were counted in June 2001. Four burrowing owls were counted on
the same survey route on a night survey in July 2001.
Lost Hills Saltbush
Lost Hills saltbush is an annual that flowers from May to August
(Service 1998). It reaches a maximum height of eight inches (Service
1998). The male and female flowers are mixed in small clusters in the
upper leaf axils. The fruiting bracts are broadly triangular, irregularly
toothed, and may or may not have tubercles. Lost Hills saltbush is listed
as a Federal species of concern. It is one of the plant species included in
the Recovery Plan for Upland Species of the San Joaquin Valley,
California (Service 1998).
This species exists in the Valley sink scrub, Valley saltbush scrub,
nonnative grassland, and alkali meadow plant communities (Service
1998). At most sites, Lost Hills saltbush grows in dried beds of alkaline
pools; however, one population, south of McKittrick, exists on exposed
slopes rich in gypsum (Service 1998). Associated species include
common saltbush, spiny saltbush, alkali heath, saltgrass, and seepweed
(Service 1998). Valley-floor populations exist at elevations of 165 to 280
feet (Service 1998).
Prior to 1980, Lost Hills saltbush was reported in three general areas:
north of Lost Hills; Mendota in Fresno County; and the Carrizo Plain in
San Luis Obispo County (Service 1998). In the 1980s, a number of
additional sites were discovered, and the species was confirmed to exist
near Lost Hills and on the Carrizo Plain (Service 1998). The Lost Hills
and Carrizo Plain sites represented large (greater than 10,000 plants)
metapopulations, but most sites had a few hundred individuals or less in
1993 (Service 1998).
Lost Hills saltbush has been eliminated in some areas by converting land
to agricultural use (Service 1998). Threats to this species include
degraded habitat by livestock grazing, commercial and agricultural
development, flooding for waterfowl management, and off