HELMINTH INFECTIONS IN THE TOWNSENDS GROUND-SQUIRREL DURING DROUGHT

From February to June 1992, 117 Townsend's ground squirrels (Spermophi lus townsendii) were collected for necropsy on 11 open and 10 shrubby sites at the Snake River Birds of Prey Area, Ada County, Idaho. Cumula tive precipitation was well below the 50-yr mean during the study peri od. Four species of helminths were recovered during the study: Hymenol epis citelli (10%, 12 of 117), Pterygodermatites coloradensis, sensu H all 1916, (5%, 6 of 117), Syphacia citelli (3%, 4 of 117), and Spirura infundibuliformis (2%, 3 of 117). Hymenolepis citelli was present on 8 of 11 (73%) of the more stressful open sites vs. 2 of 10 (20%) of th e shrub sites. Prevalence of infection with H. citelli was not signifi cantly different between the 2 site types. There were no significant d ifferences in prevalence of infection between males and females or adu lts and juveniles for any helminth species. Hymenolepis citelli was pr esent in all months sampled except June, but there was no significant increase or decrease in prevalence as the drought progressed. The ethe r helminths were observed in 2 or fewer months. Only a single squirrel was infected with 11 helminth species. Each helminth species occurred in a unique region of the squirrel gut. Measurements are given for th e first intact females of P. coloradensis, increasing the size ranges for females of this species.