Nesting of the Sage Thrasher, Sage Sparrow, and Brewer's Sparrow in Southeastern Idaho

Publisher Website
Google Scholar
Abstract
The territory size, mating success, nest placement, nest development and nesting success of the 3 passerine species restricted to the sagebrush (Artemisia tridentata) habitat in southeastern Idaho [USA] were examined. Territories defended by male sage thrashers (O. montanus) were larger than those defended by either sage sparrows (A. belli) or brewer''s sparrows (S. breweri). All but 1 of the territorial sage thrashers (n = 19) were successful in securing mates and nesting. Fifty-three percent of the territorial sage sparrows (n = 30) and 23% of the displaying brewer''s sparrows (n = 30) secured mates and nested. Thrashers nested either on the ground below sagebrush or in the branches of sagebrush plants. Brewer''s and sage sparrows nested only in the shrub canopy of sagebrush. Average incubation and nesting periods (rounded to the nearest whole day) for the sage thrasher, sage sparrow and brewer''s sparrow were 15 (n = 9) and 12 (n = 7) days, 14 (n = 5) and 10 (n = 7) days, and 11 (n = 1) and 9 (n = 1) days, respectively. Sage thrashers (n = 49) and sage sparrows (n = 17) had a similar probability of nesting success (0.45 and 0.40, respectively), while the Mayfield success rate for brewer''s sparrows (n = 7) was 0.09. Male sage sparrows that attracted mates established larger territories than those that failed to mate. Brewer''s sparrows nested .apprx. 10 days later than the other species, which probably resulted in their lower nesting success, since nest site requirements of all species were similar.

This publication has 0 references indexed in Scilit: