Bird occupancy and richness in ponderosa pine forests with contrasting forest structure and fire history

We compared the effects of two contrasting silvicultural treatments and prescribed fire on bird occupancy at Blacks Mountain Experimental Forest. Each silvicultural treatment was applied to two approximately 100aha units within each of three blocks. Prescribed burning was applied to one-half of each silvicultural treatment in a split-plot design. Occupancy was estimated at eight points in each plot for 11 bird species and three foraging guilds (bark gleaners, woodpeckers, and foliage gleaners). The frequencies of species detections on the point counts were used to estimate species richness on each plot. Occupancy did not differ among treatments for any of the guilds. Four of the 11 bird species, the American robin (Turdus migratorius L., 1766), the chipping sparrow (Spizella passerina (Bechstein, 1798)), the white-breasted nuthatch (Sitta carolinensis Latham, 1790), and the western tanager (Piranga ludoviciana (A. Wilson, 1811)), showed responses to the treatments. Species richness did not differ between the silvicultural or the burn treatments. The general lack of response of the bird community to the silvicultural and burn treatments is likely a result of the relatively large size of the trees and snags retained on both silvicultural treatments, the low intensity of the prescribed burns, and the lack of a strong contrast in tree density between the silvicultural treatments.