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Previous research examining the influences of post-fire salvage logging on
abundances of birds has focused primarily on the response of cavity-nesting species.
There is limited research in regard to the impact of salvage logging on a broader range
of bird species. In addition, little is known about how different intensities of salvage
logging influence bird abundances. I compared densities and relative abundances of
bird species among two different intensities of salvage logging and an unsalvaged
treatment in a post-fire forest of mixed conifers at Davis Lake, Oregon. I also
examined the potential of vegetation variables that describe habitat structure to predict
densities of birds, and the use of snags for foraging by two species of woodpeckers.
Salvage logging influenced the density or relative abundance of seven species of
birds, though the pattern of the influence varied. Five species (black-backed
woodpecker, hairy woodpecker, western wood-pewee, brown creeper, and yellowrumped
warbler) had greater densities or relative abundances in the unsalvaged
treatment than in either treatment of salvage logging. Two species (dark-eyed junco
and fox sparrow) had greater densities in salvaged treatments than in the unsalvaged
treatment. Salvage logging did not significantly influence density or relative
abundance of eight species (red-breasted nuthatch, white-breasted nuthatch, dusky
flycatcher, house wren, American robin, western tanager and chipping sparrow) and
one genus of swallows (Tachycineta).
Densities of yellow-rumped warblers increased with increasing density of
snags. Densities of fox sparrows and dark-eyed juncos increased with increasing
volume of shrubs. Vegetation variables did not strongly predict densities or relative
abundances for twelve species and one genus of birds.
Diameter of snags selected for foraging by black-backed and hairy
woodpeckers did not differ between species of woodpecker or among treatments of
salvage logging. Both species of woodpeckers selected snags for foraging with larger
diameters than the mean diameter of snags in both unsalvaged and salvage treatments.
Salvage logging influenced densities or relative abundances of some noncavity
nesting birds and cavity-nesting birds. Maintaining unsalvaged areas in burned
forests will provide habitat for species of birds negatively influenced by salvage
logging. Retaining large snags after salvage logging will provide foraging habitat for
woodpeckers. |
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