EFFECTS OF SILVICULTURAL MODIFICATIONS OF TEMPERATE RAIN-FOREST ON BREEDING AND WINTERING BIRD COMMUNITIES, PRINCE-OF-WALES-ISLAND, SOUTHEAST ALASKA

We inventoried breeding and wintering bird communities in four treatme nts of temperate rainforest on Prince of Wales Island, southeast Alask a during 1991-1992 and 1992-1993. The four forest treatments sampled i ncluded: (1) young growth (20 years) originating from clearcut logging with no silvicultural modification (non-modified), (2) young growth ( 20 years) precommercially thinned along uniformly-spaced thinning grid s (thinned), (3) young growth (20 years) with gaps in the overstory ca nopy created by felling trees in 0.05-ha openings (gapped), and (4) vi rgin old growth (greater than or equal to 150 years). Of 16 common bre eding bird species observed, six showed significant responses to young -growth modifications. One species was more abundant and two species w ere less abundant in thinned sites, while one species was more abundan t and two species were less abundant in gapped sites than at least one of the other treatments. None of the three common wintering species o f birds observed was influenced by young-growth modification. Breeding bird communities, in general, were less similar between young- and ol d-growth treatments than among young-growth treatments. Three of the 1 6 common breeding bird species were more abundant in old growth than e ach of the young-growth treatments and one uncommon species was detect ed almost exclusively in old growth during both the breeding and winte ring seasons. Four other breeding bird species were more abundant in y oung-growth treatments than in old growth. Higher use of old growth by wintering birds was related to winter severity. To enhance habitat fo r wintering and breeding birds we recommend: (1) thinning young growth along variable-spaced grids to create additional canopy layers and im prove snow-intercept properties of young growth for canopy-foraging bi rds, (2) retention of old-growth clumps in clearcuts for bird species associated with old-growth structure, and (3) long-term conservation o f old-growth temperate rainforest for breeding and wintering birds pos itively associated with old growth.