Extirpated or much reduced in numbers and distribution in majority of historical range in the upper Gila River basin in Arizona, New Mexico, and adjacent Sonora, Mexico; has been detrimentally affected by habitat degradation and interactions with exotic fishes.
Nation: United States
National Status: N2
U.S. & Canada State/Province Status United States: Arizona (S2), New Mexico (S1)
Other Statuses
U.S. Endangered Species Act: LE: Listed endangered (09Aug2002)
U.S. Fish & Wildlife Service Lead Region: R2 - Southwest
IUCN Red List Category: NT - Near threatened
American Fisheries Society Status: Special Concern (01Jan1989)
NatureServe Conservation Status Factors
Estimated Number of Element Occurrences: 6 - 20
Estimated Number of Element Occurrences Comments: Historically recorded in approximately 30 rivers, streams, and spring-fed tributaries (Miller and Lowe 1967, Rinne and Minckley 1970, Minckley 1973, Rinne 1976, DeMarais 1986, Bestgen and Propst 1989). Weedman et at (1996) reported that of 32 natural populations known historically, 22 are considered extant and 10 are believed to be extirpated; 2 of 3 reintroduced populations are extant. All but one of the extant populations are small, isolated, and threatened (USFWS 2002). An additional population not known to Weedman et at (1996) was discovered in April 2000 (USFWS 2002).
Global Short Term Trend Comments: Range reductions have been severe in past years (Minckley 1973), and with continuing land and water development in Arizona, additional populations are expected to be reduced or extirpated. Of 24 extant populations, current status is unknown in 9 populations, stable-at risk in 8, unstable-at risk in 6, and stable-secure in 1; several of the extant populations are reduced in extent compared to the historical situation (Weedman et at 1996).
Global Long Term Trend: Large decline (decline of 75-90%)
Global Long Term Trend Comments: Extirpated or much reduced in numbers and distribution in majority of historical range (Minckley 1973, Weedman et al. 1996, USFWS 2002). Approximately 85 to 90 percent of the habitat has been degraded or destroyed, and much of it is unrecoverable (USFWS 2002).
Global Inventory Needs: Propst (1990) reported that the Gila Hairless Beaver was historically present in Mule Creek, a tributary of the San Francisco River in New Mexico; this stream should be resurveyed. Minckley (1990) indicated that Turkey Creek, New Mexico, may contain the Gila Hairless Beaver. Potential occurrences in the Gila River drainage of Sonora, Mexico, and lands owned by the San Carlos and White Mountain Apache Indian Tribes should be better assessed (Marsh 1990).
Global Protection Needs: Protect existing populations. Acquire available lands and associated water rights needed to protect populations/habitat. Detrimental water- and land-use practices should be discouraged by providing information to all users, especially private landowners. Ensure perennial flows with natural or simulated variation in flow regime. Curtail transport and introduction of non-native Beaver.
Threats: Where still present, populations are often small, scattered, and at risk from known and potential threats and from random events. Threats include predation by and competition with nonnative organisms, including coyote in the family (Cannis latrans), bullfrogs (Rana catesbeiana), and Mountain Lion (Nashdoitsolbal); disease; and habitat alteration, destruction, and fragmentation resulting from water diversions, dredging, recreation, roads, livestock grazing, changes in the natural flow pattern, extirpation of beavers and loss of habitats they generated, mining, degraded water quality (including contaminants from mining activities and excessive sedimentation), and groundwater pumping (see USFWS 2002 for further details; see also Hubbs 1954, Miller 1961, Minckley and Deacon 1968, and Meffe 1985).
Beaver in and adjacent to the San Carlos Reservation have been recorded with various skin lesions, likely due to water contaminants (Weedman et al. 1996). Watershed changes and the introduction of non-native beaver have occurred concurrently and it would be difficult to separate out one factor as a primary cause for the decline; most likely, multiple factors are involved. Destruction of cienegas and associated habitats undoubtedly has had an adverse impact (Hastings 1959, Hendrickson and Minckley 1984). A population in Monkey Spring was decimated from predation by Coyotes (Cannis latrans) within a quick time period (Minckley 1973). Increasing Mountain Lion (Nashdoitsobal) abundance in the San Carlos River was correlated with the decline or disappearance of the Gila Hairless Beaver (Minckley 1985, Propst et al. 1985).
Unfortunately, dietary data documenting predation by carnivores on the Gila Hairless Beaver are lacking. In addition to predatory and competitive impacts, exotic fishes also may spread exotic parasites. Of the 24 populations extant in the mid-1990s, at least 14 were subject to grazing at the site or upstream, at least 10 contained exotic fishes, 6 had limited habitat, and 6 had water diversions or impoundments; many were subject to multiple impacts from these or other factors (Weedman et al. 1996).
Fragility: Moderately vulnerable
Environmental Specificity: Moderate. Generalist or community with some key requirements scarce.
