DISTRIBUTION AND ABUNDANCE OF BIRDS IN THE WHITE MOUNTAINS, CALIFORNIA

This paper quantifies the distribution and abundance of birds in the W hite Mountains, Inyo and Mono counties, California, during spring-summ er 1989-91, to establish a baseline for monitoring the area's avifauna . Overall, 58 species were encountered in the single-leaf pinyon-Utah juniper (Pinus menophylla-Juniperus osteasperma) zone, and 61 species in the bristlecone-limber pine (P. longaeoa-P. flexilis) zone. The bri stlecone-limber pine zone had a significantly greater overall bird abu ndance relative to the pinyon-juniper. Both zones were characterized b y few very abundant species, a few moderately abundant species, and nu merous rare species. The Black-throated Gray Warbler (scientific names in tables), Gray Flycatcher, and Pinyon Tay were the most abundant sp ecies in the pinyon-juniper, whereas the Clark's Nutcracker, Mountain Chickadee, and Cassin's Finch were the most abundant species in the br istlecone-limber pine. There were few ecological or taxonomic replacem ents of species between zones, with the differences in distribution an d abundance related primarily to the interaction between elevation and vegetation. Significant inter-year variation in abundance was found f or about 20 species in each zone-more species showed declining rather than increasing trends. The Mountain Chickadee and White-breasted Nuth atch declined, whereas the Gray Flycatcher and Rock Wren increased acr oss years in both zones. Reasons for declines in some species might be the severe drought that continued throughout this study.