PERSISTENCE OF MOUNTAIN SHEEP POPULATIONS IN ARIZONA

We used data for mountain sheep (Ovis canadensis) in Arizona to examin e the theory that populations with < 50 individuals will become extinc t. We found no significant difference in extinction rate between popul ations with 150 individuals (n = 12; four extinctions) and populations with > 50 individuals (n = 8; two extinctions). We question three ass umptions of the theory: 1) that different races of mountain sheep resp ond in a similar manner regardless of habitats, 2) the criteria used t o define a population, and 3) the accuracy of population estimates.