RIPARIAN FOREST STRIPS AS HABITAT FOR BREEDING BIRDS IN BOREAL FOREST

Riparian forest strips are usually protected from logging for their buffer effect on aquatic habitats. However, their value to terrestrial wildlife is unknown. From 1989 to 1992, we compared bird abundance and species composition in 5 experimental riparian forest strips (20-m, 40-m, 60-m, and control [>300 m wide], intact strips, and 20-m-wide thinned strips), in boreal balsam fir (Abies balsamea) stands, for 3 years following clear-cutting. Bird densities increased 30-70% (P < 0.05) in all strips the year after cutting and decreased (P > 0.05) thereafter to approximately pretreatment levels. The 20- and 40-m-wide riparian strips had highest mean bird densities, but also the fastest (P < 0.05) decreases thereafter. By the third year after clear-cutting, forest-dwelling species were less (P = 0.01) abundant than ubiquitous species in the 20-m strips. The golden-crowned kinglet (Regulus satrapa), Swainson's thrush (Catharus ustulatus), blackpoll warbler (Dendroica striata), and black-throated green warbler (D. virens) became nearly absent in 20-m strips. The removal of 33% of the trees in some 20-m strips r