Frequency of birth and lambing sites of a small population of mountain sheep

We examined frequency of lambing, lamb survivorship, site fidelity for lamb ing areas, and described lambing areas of a small population of mountain sh eep (Ovis canadensis mexicana) in the Little Harquahala Mountains, Arizona from 1989 to 1991. We collected data from 57% of the population by radio-co llaring 10 adult females and two lambs, and relocated the females during an d after parturition each year (266 relocations). Nineteen lambs were born t o 10 females. Six of these lambs survived greater than or equal to 6 months and 13 lambs lived an average of 34 days. One lamb died from a fall and on e died from being stepped on; the causes of the other 11 mortalities are un known. Five females did not raise any lambs that lived greater than or equa l to 6 months in ally year. No female raised a lamb that lived greater than or equal to 6 months in 2 consecutive years. Lambing areas used by individ ual females were separated by more than 7 km each year. No female used a la mbing area used by another female. Percent slope, topographic position, ant i vegetation composition were not different at lambing sites compared to si tes used during other times of the year. Habitat used by females during the period around parturition had more thermal cover than random sites. Habita t used by female sheep throughout the year was steeper, higher in topograph ic position, and had more brittle bush (Encelia farinosa), creosote bush (L arrea tridentata), pale verde (Cercidium microphyllum), and barrel cacti (F erocactus wislizenii) than random sites. Lambing sites are used for relativ ely short periods of time and their importance may be underestimated by bro ad scale studies of habitat use.