Breeding bird responses to three silvicultural treatments in the Oregon Coast Range

Silvicultural alternatives to clear-cutting have been suggested to promote development, retention, or creation of late-successional features such as l arge trees, multilayered canopies, snags, and logs. We assessed bird respon se to three silvicultural alternatives to clear-cutting that retained struc tural features found in old Douglas-fir (Pseudotsuga menziesii) forests and that imitated natural disturbance regimes more closely than did traditiona l clear-cutting: (1) small-patch group selection treatment representing a l ow-intensity disturbance; (2) two-story treatment, representing a moderate to high-intensity disturbance; and (3) modified clear-cut treatment, repres enting a high-intensity disturbance. We counted diurnal breeding birds 1 yr prior to and 2 yr after harvest to estimate effects of the silvicultural t reatments on bird communities compared with uncut controls. The small-patch group selection treatment was most similar in species composition to contr ol stands. The two-story treatment was more similar to the modified clear-c ut treatment. Ten bird species remained abundant following the small-patch group selection treatment. They declined in abundance in modified clearcuts and two-story stands. These species included four neotropical migratory sp ecies and five species with restricted geographic ranges and habitat associ ations. Nine species increased in response to moderate and/or high-intensit y disturbances. This group included a larger proportion of species that wer e habitat generalists, Silvicultural treatments imitating low-intensity dis turbances were most effective in retaining bird communities associated with mature forest; high-intensity disturbances such as the two-story and modif ied clear-cut treatments greatly altered bird community composition. Bird r esponses to the silvicultural treatments that we studied indicate that a va riety of stand types is needed to meet needs of all species.