Influence of riparian buffer width on bird assemblages in Western Oregon

The goals of current management practices in riparian areas in the Pacific Northwest include protecting and maintaining habitat for terrestrial wildlife. However, little is known about the use of riparian buffers by terrestrial wildlife, particularly how buffer width may affect abundance and species composition of wildlife communities. In this study, I compared bird assemblages in logged and unlogged riparian areas along headwater streams and assessed the relations between bird abundance and riparian buffer width. The abundances of 4 species of forest-associated birds that were more abundant in unlogged than in logged headwater riparian stands (Pacific-slope flycatcher [Empidonax difficilis], brown creeper [Certhia americana], chestnut-backed chickadee [Poecile rufescens], winter wren [Troglodytes troglodytes]) increased with increasing width of riparian buffers. However, 4 other species that also were more abundant in unlogged than logged riparian stands (Hammond's flycatcher [Empidonax hammondii], golden-crowned kinglet [Regulus satrapa], varied thrush [Ixoreus naevius], hermit warbler [Dendroica occidentalis]) were rarely observed in even the widest buffers sampled (40-70 m on 1 side of the stream). Although riparian buffers along headwater streams are not expected to support all bird species found in unlogged riparian areas, they are likely to provide the most benefit for forest-associated bird species if they are >40 m wide, and density of large trees within buffers is not reduced by harvesting.