Some Ectoparasites and Pathogens of the Point Arena Mountain Beaver (Aplodontia rufa nigra)

Abstract

The Point Arena Mountain Beaver (Aplodontia rufa nigra) is 1 of 7 subspecies of mountain beaver, and occurs as an entirely disjunct population in a 62 km2 area of southcentral coastal Mendocino County, CA (USFWS 1998). Although the Point Arena Mountain Beaver was listed as ' 'endangered' ' in 1991 under the federal Endangered Species Act (USFWS 1998), there are few published scientific papers regarding the biology of this subspecies, and none regarding its parasites or pathogens. We surveyed the ectoparasite fauna of the Point Arena Mountain Beaver and estimated the prevalence of ectoparasite infestation (the proportion of individuals in the host population that are parasitized by each taxon) to provide information on disease or other threats that might affect the subspecies. Approximately 30 ectoparasitic species, including mites (Acari), ticks (Ixodida), fleas (Siphonaptera), and a beetle (Coleoptera) have been documented on other subspecies of mountain beavers (Ferris 1918; Cooley and Kohls 1945; Whitaker and others 1979; Canaris and Bowers 1992). Some of these ectoparasites are host-specific, likely as a result of the unique phylogeny and ecology of the mountain beaver (Feldhamer and others 2003). Given the highly host-specific nature of the mountain beaver ectoparasite community, and the conservation status of the Point Arena subspecies, we also sought to document the presence of any hostspecific ectoparasitic arthropods potentially at risk (Stork and Lyal 1993; Lewis and Lewis 1994). We also tested some of the ectoparasites collected and tissues from salvaged Point Arena Mountain Beavers for evidence of selected