Effect of Firewood Harvesting on Birds in a California Oak-Pine Woodland
Academic Article
Overview
Identity
Additional Document Info
Other
View All
Overview
abstract
Despite a history of oak clearing and thinning in California, little is known about the effects of firewood harvesting on wildlife in oak woodlands. We studied the effect of firewood harvesting on population trends of birds during the breeding season in an oak-pine woodland in the foothills of the northern Sierra Nevada, California. During fall-winter of 1993-94, total tree basal area on 30 3.1-ha study plots was reduced by approximately 23% via removal of commercial-grade oaks, but all old-growth trees and trees with obvious nest cavities or woodpecker granaries were preserved. An additional 30 plots represented controls. We used point counts to derive a population index of birds 1 breeding season before and 2 breeding seasons after harvesting. We detected population shifts in 14 species (7 year-round residents, 4 breeding migrants, 1 migrant, 2 winter residents), of which 10 showed consistent population increases, 2 showed consistent population decreases, and 2 showed varying population changes in the 2 seasons after harvesting. Six of the species that increased on harvested plots appeared to respond to the presence of brush piles. Responses of other species were less clearly linked to a particular aspect of vegetation change. Although we found a negative effect of harvesting on only 2 species, the Pacific-slope flycatcher (Empidonax difficilis) and Hutton's vireo (Vireo huttoni), statistical power to detect anything less than total extirpation of many uncommon species was <0.8. Our results indicate that small-scale firewood harvests that reduce basal area by <25% and preserve nest cavities and granary trees have minimal negative short-term effects on most of the more common bird species present during the breeding season, but we caution that effects on uncommon species may have gone undetected. Further studies are necessary to evaluate the potential importance of site fidelity, brush-pile decay, and vegetation recovery in affecting species' responses over the long term.
