Breeding ecology of passerine birds in a sagebrush-dominated community

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In 1980 and 1981, nest-site selection by Sage Sparrows (Amphispiza belli) and Brewer's Sparrows (Spizella breweri) was studied in a sagebrush community. Brewer's Sparrows nested in areas with large, dense sagebrush and low herbaceous plant coverage; Sage Sparrows preferred areas with clumped sagebrush distributions. Both species strongly preferred to nest in large, living shrubs and did not differ significantly with respect to any of the nest-shrub variables measured. Brewer's Sparrows placed their nests significantly higher and closer to the perimeter of shrubs than did Sage Sparrows. Sage Sparrows avoided placing nests on southwest sides of shrubs, whereas Brewer's Sparrows did not avoid any side of the nest shrub. Vertical vegetation profiles at nest sites of the two species differed; Sage Sparrow nest-site vegetation was more dense. I suggest that 1) Sage and Brewer's Sparrows probably do not compete for nest sites, 2) selection of an area for nesting may be influenced most strongly by foraging strategies, and 3) selection of a nesting substrate and nest placement within it may be influenced primarily by microclimatic factors.

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Reference Code: U82PET01IDUS

Full Citation: Peterson, K. L. 1982. Breeding ecology of passerine birds in a sagebrush-dominated community. Unpublished dissertation, Iowa State University, Ames. 66 pp.

Location: ANIMAL EF: BIRDS