Effects of silvicultultural modifications of temperate rainforest on breeding and wintering bird communities, Prince of Wales Island, southeast Alaska

We inventoried breeding and wintering bird communities in four treatments
of temperate rainforest on Prince of Wales Island, southeast Alaska during 1991-1992 and
1992-1993. The four forest treatments sampled included: (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 grids (thinned),
(3) young growth (20 years) with gaps in the overstory canopy created by felling trees in
0.05-ha openings (gapped), and (4) virgin old growth (2 150 years). Of 16 common breeding
bird species observed, six showed significant responses to young-growth modifications. One
species was more abundant and two species were less abundant in thinned sites, while one
species was more abundant and two species were less abundant in gapped sites than at least
one of the other treatments. None of the three common wintering species of birds observed
was influenced by young-growth modification. Breeding bird communities, in general, were
less similar between young- and old-growth treatments than among young-growth treatments.
Three of the 16 common breeding bird species were more abundant in old growth
than each of the young-growth treatments and one uncommon species was detected almost
exclusivelyi n old growth duringb oth the breedinga nd wintering seasonsF. our other breeding
bird species were more abundant in young-growth treatments than in old growth. Higher
use of old growth by wintering birds was related to winter severity. To enhance habitat for
wintering and breeding birds we recommend: (1) thinning young growth along variablespaced
grids to create additional canopy layers and improve snow-intercept properties of
young growth for canopy-foraging birds, (2) retention of old-growth clumps in clearcuts for
bird species associated with old-growth structure, and (3) long-term conservation of oldgrowth
temperate rainforest for breeding and wintering birds positively associated with old
growth.