Making Room for the by Michael Burroughs Amargosa

When a university biologist any oasis in the desert, competition for studying the Amargosa toad (Bufo limited resources can be intense, and nelsoni) concluded in 1994 that only 32 the availability of water often deter- adult remained in the Oasis mines survivability for humans and Valley of southern Nevada, a petition to wildlife alike. In the , list this as an endangered relatively large tracts of private land species soon followed. During the occur mostly along the riparian corridor, subsequent 12-month status review, adjacent to public lands administered by intensified survey efforts located the BLM. Because of the sparse human hundreds of toads at other sites in the population and the absence of commer­ The male Amargosa toad does not area. Based on these discoveries and cial or industrial development in the have an advertising call typical of commitments by land managers to area, the Amargosa toad is not currently most toads. Seeking shelter in rodent initiate actions to conserve the toad, the threatened with the kinds of burrows, rock crevices, or debris piles during the day, the Amargosa Fish and Wildlife Service (FWS) destruction many other species face. In toad becomes active after dark. From determined that listing the Amargosa fact, the toad may even benefit from February through June, males toad as endangered or threatened was low-impact land uses that provide cover typically move to the water’s edge to not warranted. and prey. For example, toads congre­ await the arrival of females. A large Endemic to the Oasis Valley in gate under street lights at night to take female toad may lay as many as 6,000 southern Nye County, Nevada, the advantage of the abundance of insects, eggs in long strands often twined Amargosa toad is found only along a their primary food source. through vegetation. Photo by Michzel Burroughs 10-mile (16-kilometer) stretch of the Amargosa River and interconnected Threats spring systems. Recognizing the biologi­ Other than the obvious vulnerability cal uniqueness of this area, which that comes with a narrow distribution supports a number of rare and and relatively low population size, the plants, the Nevada Division of Wildlife Amargosa toad also faces certain other (NDOW), Bureau of Land Management threats. In the mid-1980’s, crayfish (BLM), FWS, and others have united to (Procambarus sp.) were introduced to develop a conservation strategy aimed the Oasis Valley, and they have ex­ at ensuring the survival of the toad and panded into spring and riparian systems the ecosystem on which it depends. inhabited by Amargosa toads. Attempts At the southern end of the toad’s to eradicate or control this non-native distribution lies the rural community of crustacean have been mostly unsuccess­ Beatty, situated between the Nevada ful. Crayfish likely consume eggs of the Test Site to the east and Death Valley toad and Oasis Valley speckled dace, as National Park to the west. Surrounded well as tadpoles and fish larvae. Wild by alkali soils, rocky and often barren burros, another non-native species slopes, and Mojave/Great Basin Desert found throughout the valley, trample vegetation, the lush springs and riparian wet areas and foul surface water. corridor of the valley provide important Another ecological impact is caused by habitat for such species as the Amargosa tamarisk or saltcedar (Tamarisk toad, Oasis Valley speckled dace chinensis), an invasive non-native tree (Rhinichthys osculus ssp.), and numer­ that has become established along ous neotropical migratory birds. As with stretches of the river. In areas where

REPRINTED FROM THE BULLETIN NOVEMBER/DECEMBER 1999 VOLUME XXIV NO. 6 saltcedar has become a dominant County will also work with State and canopy species, biologists are con­ Federal agencies to develop conserva­ cerned that the desert riparian ecosys­ tion easements and voluntary manage­ tem may be converted to a system ment agreements. unsuitable for natives. Potential human In 1998, the NDOW, with funding impacts to the toad include water from the Species at Risk Program, diversions, collection and vandalism, initiated a long-term mark/recapture off-highway vehicle activity within the study using passive integrated transpon­ river corridor, flood-control activities, der (PIT) tags to identify individual and the potential for urban or commer­ toads. Recapture data cial development. will provide informa­ tion on such important Conservation Agreement subjects as survival, A small group of government and movement, and growth university biologists formed the of individual toads. The Amargosa Toad Working Group (ATWG) BLM is in the process of in 1994 to address potential threats, designating the Oasis develop a conservation strategy, and Valley as an Area of oversee management. Its members have Critical Environmental developed a draft agreement that covers Concern, which will not only the toad but also other provide additional pro­ vulnerable species in the area, including tection to both occu­ the threatened desert tortoise (Gopherus pied and potential toad agassizii), the endangered southwestern habitat on lands admin­ willow flycatcher (Empidonax traillii istered by the BLM. extimus), and 18 additional species of Local conservation concern that occur in the Oasis Valley. partners include long- Because so little is known about the term residents and re­ Amargosa toad, studies of life history cently arrived retirees. and predator interactions are identified Several private land- in the agreement as high-priority owners allow State and conservation needs. Federal biologists un­ The Nature Conservancy (TNC) has limited access to their been a long-term advocate for the toad’s lands to search for the conservation. In July 1999, TNC accom­ secretive toads. One landowner in The Amargosa River is home to a plished a major milestone with the particular has joined the cause by number of rare plants and animals. purchase of a 140-acre (60-hectare) donating time and heavy equipment to Photo by Michael Burroughs ranch outside Beatty with plentiful work with biologists to modify springs springs, wetlands, and toads. Acquisition and create ponds on his 320-acre (130- of this key parcel gives biologists the ha) quarry and ranch north of town. opportunity to conduct experimental The ATWG is optimistic that conser­ habitat management and provide an vation and management actions will ecological showcase to the local continue to improve the status of the community. Another major conservation Amargosa toad, along with the ecosys­ achievement took place when Nye tem upon which it and other sensitive County, a relatively large county species depend. consisting mostly of small rural commu­ nities surrounded by Federal land, Michael Burroughs is a Fish and became a cooperator with the agree­ Wildlife Biologist in the FWS Southern ment. As a cooperator, Nye County will Nevada Field Office, located in Las assume the lead for public involvement Vegas, Nevada. and community coordination on the group’s conservation actions. Nye

REPRINTED FROM THE ENDANGERED SPECIES BULLETIN NOVEMBER/DECEMBER 1999 VOLUME XXIV NO. 6