Seasonal changes in detectability of sage and Brewer's sparrows

Publication Type:

Journal Article

Authors:

Best, Louis B.; Petersen, Kenneth L.

Source:

Condor, Cooper Ornithological Society, Volume 87, Issue 4, p.556-558 (1985)

Call Number:

A85BES01IDUS

URL:

https://sora.unm.edu/node/103626

Keywords:

Amphispiza belli, Spizella breweri

Abstract:

The Sage Sparrow (Amphispiza belli) and Brewer's Sparrow (Spizella breweri) are two of the dominant bird species breeding in the sagebrush-grasslands of Idaho, Oregon, and Washington. Best and Petersen documented the effects of stage of the breeding cycle on Sage Sparrow detectability, but seasonal changes in detectability could not be derived directly from the breeding cycle data because the birds nested asynchronously. Seasonal changes in detectability of this species and the Brewer's Sparrow have yet to be reported. In this study, our objective was to document changes in the detectability of these two species during the breeding season. Because most birds were marked and all territories we mapped, we could derive seasonal profiles detectability, adjusted for seasonal changes in bird densities. Such profiles may be used when planning bird-count schedules and when interpreting census results for sagebrush-grassland bird communities. The study was conducted in 1981 and 1982 on the Idaho National Engineering Laboratory (INEL), approximately 11 km south of Howe, Butte County, Idaho.