AVIAN ABUNDANCE IN RIPARIAN ZONES OF THREE FOREST TYPES IN THE CASCADE MOUNTAINS, OREGON

摘要

We surveyed bird populations along headwater streams of old-growth, ma-ture, and young coniferous forests of the Oregon Cascade Mountains during summer and winter. Brown Creepers (Certhia americana), Chestnut-backed Chickadees (Parus rufes-cens), Golden-crowned Kinglets (Regulus satrapa), Evening Grosbeaks (Hesperiphona ves-pertinus), and Winter Wrens (Troglodytes troglodytes) were common in all stand types. During the summer, abundances of Brown Creepers, Hammond's Flycatchers (Empidonax hammondii), Hermit/Townsend's warblers (Dendroica occidentalis), and Chestnut-backed Chickadees were significantly higher in old-growth and mature forests compared to young forests. Species richness and densities generally were not significantly different among the stand types during winter. However, numbers of Chestnut-backed Chickadees, Evening Grosbeaks, Golden-crowned Kinglets, Hairy Woodpeckers (Picoides villosus), and Winter Wrens were much higher in the winter than in summer. Swainson's Thrushes (Catharus ustulatus) and Rufous Hummingbirds (Selasphorus rufus) were more abundant in riparian areas in this study compared to other studies in upland forests and may be riparian associates along these headwater streams.