Field Notes
U.S. Fish & Wildlife Service
Field Notes Entry   
VENTURA FWO: Amargosa River Partnerships Conserve a Unique Mojave Desert Ecosystem
California-Nevada Offices , December 31, 2009
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Mouth of the Amargosa Canyon, showing riparian habitat that is typical of this area. (photo: Brian Croft, USFWS)
Mouth of the Amargosa Canyon, showing riparian habitat that is typical of this area. (photo: Brian Croft, USFWS) - Photo Credit: n/a
Amargosa vole habitat on a private parcel that is being acquired through section 6 funding. (photo: Brian Croft, USFWS)
Amargosa vole habitat on a private parcel that is being acquired through section 6 funding. (photo: Brian Croft, USFWS) - Photo Credit: n/a

by Brian Croft, Ventura FWO
The Amargosa River, which stretches 125 miles from near the town of Beatty, Nevada to its terminus at Badwater on the floor of Death Valley, California is a unique desert ecosystem, hotspot of species endemism, and one of the most isolated areas of the Mojave Desert.  Along its course in California, perennial surface water exists at Shoshone, Tecopa, and the Amargosa Canyon where numerous springs release ground water into the river.  These springs support riparian, wetland, and salt flat habitats for a wide array of rare, sensitive species and migratory birds.  Despite its isolated location, the Amargosa River and the species that it supports are increasingly under threat from non-native species, groundwater development, and habitat degradation.   

Because of the wildlife values of the Amargosa River and the threats it faces, the Ventura Fish and Wildlife Office (VFWO) has coordinated several projects with other  federal and state agencies and non-governmental organization (NGO) partners to benefit listed and sensitive species along this unique river.  Major locations of focus have been the salt-encrusted mudflats of the Lower Carson Slough, the wetland areas around Tecopa Hot Springs, and the springs and riparian areas of Shoshone and the Amargosa Canyon.  The species of special interest within these areas include the federally endangered Amargosa vole (Microtus californicus scirpensis), southwestern willow flycatcher (Empidonax trailii extimus), Amargosa niterwort (Nitrophila mohavensis), federally threatened Ash Meadows gumplant (Grindelia fraxino-pratensis), and a variety of migratory birds.  In addition, rare endemic species in these areas include Amargosa pupfish (Cyprinodon nevadensis amargosa), Amargosa Canyon speckled dace (Rhinichthys osculus subsp.), Shoshone pupfish (Cyprinodon nevadensis shoshone), and a variety of spring snail species.  

Habitat degradation due to salt cedar infestations in these locations has changed the habitat quality for many of these listed and sensitive species.  Nest parasitism by brown-headed cowbirds has adversely affected nest success for Bell’s vireos and a variety of neotropical migratory birds.  Other invasive species such as house mice, crayfish, and bullfrogs have adversely effected populations of native fish and the Amargosa vole due to unnatural predation and competition pressures.  In addition, the ever-present threat of groundwater depletion has the potential to result in major impacts to all spring dependent species and habitats in this region. 

To address the sensitive nature of these resources and their threats, multiple agencies and NGOs have produced different plans and strategies to highlight the importance of the Amargosa River and provide goals and objectives to further its management.  These plans include the Bureau of Land Management’s (BLM) Northern and Eastern Mojave Management Plan and the Amargosa River Area of Critical Environmental Concern (ACEC) Management Plan, the Fish and Wildlife Service’s Recovery Plan for the Amargosa Vole and  Recovery Plan for the Threatened and Endangered Species of Ash Meadows, and The Nature Conservancy’s  Amargosa River Project: Initial Assessment and Conservation Strategies.  In addition, the California Department of Fish and Game’s (CDFG) wildlife action plan identifies multiple goals for Amargosa River species.  Many of these plans have common objectives that help focus the efforts of multiple partners on the common issues and potential projects.  This promotes collaboration among partners to prioritize actions and work together to obtain funding for planning and implementation of specific projects. 

During the past five years, the VFWO has been involved in multiple partnership efforts with the BLM, the Nature Conservancy, the Amargosa Conservancy, Natural Resources Conservation Service, PRBO Conservation Science, the California Department of Fish and Game, and key private landowners.  The primary goal of these partnerships has been to obtain funding and implement projects to address salt cedar infestations, restore riparian habitat, acquire private lands and conservation easements, control nest parasitism by brown-headed cowbirds, and obtain better data on migratory birds and groundwater resources.

Slow, controlled removal of salt cedar, accompanied by both passive and active restoration of native riparian plant species, has been a cornerstone of many of the VFWOs partnership efforts along the Amargosa River.  Since 2004, our partnerships have prioritized, funded, and implemented several projects to remove salt cedar from about 300 acres of the Amargosa River and adjacent seed source areas.  These efforts have resulted in almost complete removal of salt cedar from the main stem of the Amargosa River at Shoshone and other project sites in the Amargosa Canyon and at China Ranch.  This has promoted significant regeneration of mesquite- and willow- dominated plant communities at project sites.  As a member of this partnership, the VFWO has contributed funds and provided additional support in planning and approving projects.

Another focus of the partnership efforts on the Amargosa River have been land acquisition, which is intended to consolidate management within the BLMs ACEC to allow for better and more consistent management of listed species and other sensitive resources.  Since 2006, the VFWO has worked with CDFG and the other partners to prioritize parcels for acquisition; this partnership has resulted in the award of two separate non-traditional section 6 grants to purchase 66 acres of land and conservation easements in the Tecopa Hot Springs area that support habitat for the Amargosa vole and Amargosa niterwort.  These efforts complement acquisition and conservation easement efforts performed by the Nature Conservancy in this area during the past two decades

Since 2004, the VFWO and BLM have provided funds for annual point-count surveys and nest monitoring for neotropical migratory birds along the Amargosa River to monitor changes in populations, nest success, and avian diversity as riparian restoration efforts progress.  The goal is to determine how these habitat restoration efforts affect the avian species and populations.  Following initial survey results in 2005, that identified a high level of nest parasitism, the VFWO embarked on a program of cowbird control on the Amargosa River in partnership with PRBO Conservation Science.  Since this program began, monitoring results have shown decreases in parasitism rates by brown-headed cowbirds and substantial improvement in nest success for many neotropical migratory birds.  In addition, some birds, like the Bell’s vireo, are nesting in areas on the Amargosa River where we have not located them before.

In the coming years, the partnership hopes to continue to remove salt cedar from the Amargosa River and control brown-headed cowbirds.  Most goals associated with land acquisition have been accomplished, but the partnership will continue to pursue a few strategic parcels of high conservation benefit.  In 2009, the VFWO and CDFG obtained $63,500 in section 6 traditional grant funding for a distribution and abundance survey for the Amargosa vole.  Field surveys will begin for this project in the spring of 2010, and will help to implement actions from the recovery plan for this species.  The VFWO has also submitted a grant proposal to the National Fish and Wildlife Foundation for $27,500 to fund the development of a habitat suitability model for the Amargosa niterwort that would cover all potential locations for this species in California and complement similar efforts that have already occurred in Nevada.  In addition, this grant, along with matching contributions from partner organizations, would fund surveys to determine the current distribution and occurrence size for this species in California and initiate a groundwater monitoring program for each occurrence.  If funded, this project would gather critical information needed for recovery of this species and complement similar data collection exercises by the Amargosa Conservancy.

Restoration of riparian and wetland habitats and recovery of listed species along the Amargosa River is a process that requires a common vision for this region and implementation of multiple long-term projects to address various issues and threats.  Because of the common goals of all partners involved, development of a core partnership has not been difficult.  Our common vision has greatly reduced any conflict over priorities when it comes to deciding what projects the group should attempt.  Much work remains to be done and many threats still need to be addressed, but the presence of this long-standing partnership of dedicated people who care about a region that most people know little about has proven to be crucial to our success.

Contact Info: Brian Croft, 951-697-5365, Brian_Croft@fws.gov
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