The ecology of native Arizona gray squirrels: impacts of introduced Abert’s squirrels

John Koprowski

Arizona gray squirrels (Sciurus arizonensis) were first described about 150 years ago, yet there has not been a single publication on the ecology of this species. Often considered to be uncommon in the mountain islands of the deserts of Arizona and extending slightly into northern Mexico where the species is considered to be threatened, little is known of this large bodied tree squirrels (600-800 g). Introductions of Abert’s squirrels (Sciurus aberti) in the 1940s to many of the isolated mountains in which Arizona gray squirrels are found has been suggested to be a threat to the persistence of the uncommon natives. I have initiated studies in the Santa Catalina and Rincon Mountains of southeastern Arizona to assess current distribution of these species. Initial surveys suggest that Abert’s squirrels are common in the high elevation conifer forests where most museum specimens of Arizona gray squirrels were once collected. Arizona gray squirrels now appear uncommon in such habitats. During 2005, I will initiate a live trapping and radiotelemetric study to assess space and habitat use of these congeners in areas of syntopy and allotopy. The project is funded through 2006.

John L. Koprowski, Associate Professor, Wildlife Conservation and Management, School of Natural Resources, University of Arizona, Tucson, AZ, 85721, USA. 

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