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Highlights: [•] Retained habitat elements in private PNW clearcuts are typically rotation-aged trees. [•] Densities of standing retention were low while downed wood was abundant. [•] Bird communities were dominated by early successional and generalist species. [•] Snag retention may provide opportunity for cavity-nester conservation. [Copyright &y& Elsevier]

Abstract: Structure retention is a practice used in managed forests to assist the conservation of biological diversity, whereby green trees, dead trees (i.e. snags), and downed wood are retained during timber harvest. This activity is recognized as beneficial. However, there is little scientific support to guide the management prescriptions (e.g. patch sizes, distribution pattern). We quantified the short-term response of birds to structure retention in timber harvest areas located in the Pacific Northwest. We used a hierarchical community model to examine how attributes of retention sites (number of trees and snags, distance to forest edge) were associated with the species richness of birds using the sites. The modeling framework integrated multiple species-specific occupancy models that accounted for imperfect detection to produce estimates of species richness. We sampled a biogeoclimatic gradient by selecting harvest units within four separate regions (two in Washington, one each in Oregon and California) that support different forest types. Observations were conducted at a random selection of retention sites (e.g. patches, individual trees) within harvest units to record bird use during the breeding seasons of 2008 and 2009. Estimated occupancy and detection probabilities differed by species and region. Retained tree count was associated with an increased occupancy probability for all observed species. The community response to tree count was consistent across all study regions and years – species richness estimates increased with tree count and approximated a species–area curve. Snag count and edge distance did not significantly affect occupancy probability for any observed species, and therefore, had no relationship with species richness. These results suggest that the diversity of birds using structure retention in harvest units can be maximized at patches of >10–15 rotation-age trees. Forest managers are encouraged to group green-trees around high-quality snags and other unique wildlife trees where possible, and to vary prescriptions across stands to provide habitat heterogeneity at the landscape scale. [Copyright &y& Elsevier]

• We examined habitat associations of 18 bird species in managed stands. • Forestry treatments and years-since-harvest were poor predictors of bird abundance. • Vegetation characteristics were excellent predictors of bird abundance. • Forestry treatments influenced important vegetation characteristics for birds. • Managers could target vegetation outcomes rather than forest treatment categories. Forests are often affected by management that could influence demographics of breeding and post-breeding birds that reside within. Numerous studies have focused on immediate effects from management on wildlife soon after forestry treatment (e.g., 0–5 years); however, fewer studies have examined changes in focal species abundance over longer durations as a forest regenerates after disturbance. We examined how forest management influenced 18 conifer-associated birds during breeding and post-breeding over the forest regeneration period in a landscape dominated by forestry. To achieve this, we combined avian detection data from point count surveys conducted in lowland conifer and mixed-wood forests in Maine, New Hampshire, and Vermont with Bayesian distance-removal models and an information-theoretic framework. We estimated abundance and associations with seven common forestry treatment categories applied at the stand scale, years-since-harvest (YSH; 5–120 +), and seven vegetation variables measured within stands. Forestry treatment categories and YSH were poor predictors of abundance. Of 14 species with models having good-fitting statistical distributions while including forestry treatments and YSH as covariates, no species had associations. Of 13 species with models having good-fitting statistical distributions while including vegetation covariates, 12 had important associations between abundance and vegetation variables. Each vegetation variable was associated with abundance of some species, irrespective of the forestry treatment in which the site occurred, including spruce-fir tree composition (seven species), tree basal area (six species), midstory cover (five species), live crown ratio (three species), shrub cover (three species), tree diameter at breast height (two species), and shrub composition (one species). In a companion study, several species assemblages were associated with vegetation variables (i.e., spruce-fir tree composition, tree basal area, and tree diameter at breast height) that were associated with YSH and forestry treatments, suggesting that some forestry treatments may indirectly influence avian abundance when certain vegetation outcomes are achieved. Our results suggest that managers could target species-specific vegetation outcomes rather than more broadly categorized forestry treatment types when managing for individual focal species because of large variations in vegetative outcomes across stands within a forest treatment category. Our study informs management and conservation of biodiversity in regions such as the Atlantic Northern Forest in North America where commercial forestry is the dominant human land use. [ABSTRACT FROM AUTHOR]