Birds

Scarlet Tanager, Black-throated Green Warbler, Black-and-white Warbler - pen and ink drawingAt the Holt Research Forest we censused birds year-round for many years and have been mapping bird territories during the breeding season since 1983. We have observed 124 species of birds, 35 of which breed here. In the forest ecosystem, birds are consumers of insects, distributors and predators of seeds, and sometimes are indicators of forest condition primarily reflecting the successional stage of the forest.

We are have studied the response of the bird community to the winter 1987-88 harvest, as well as long-term trends at the Holt Forest versus regional trends. Populations of some forest interior bird species (e.g., ovenbird, black-throated green warbler, eastern pewee) decreased in harvested areas but remained stable elsewhere. Early successional-stage species (e.g., common yellowthroat, white-throated sparrow) increased in harvested areas.

Winter wren pen and ink drawingFive pairs of winter wrens, a species not previously observed at the Holt Forest, were a first-year post-harvest surprise. The wrens used the microhabitat created by slash and disappeared over several years as the slash decomposed.

Graph of number of territories by year for black-throated green warbler, ovenbird, common yellowthroat, white-throated sparrow, eastern wood pewee, and winter wren

Number of Territories by Year

While the overall impact of timber harvesting on the bird community needs more in-depth analysis, our preliminary analyses indicate that the harvest has not dramatically altered the structure of the bird community within the 40-hectare study area. We may have minimized the impacts on birds by dispersing discontinuous small harvest gaps in only a portion of the forest.