DIVERSITY AND ABUNDANCE OF LANDBIRDS IN A NORTHEASTERN INDUSTRIAL FOREST

We studied abundance and diversity of landbirds in all successional st ages of habitat in an industrial forest landscape in northern Maine. O f 9 broad habitat categories, clearcuts and mature hardwood forests ha d the lowest avian diversity, but these 2 habitats each contained many individual species that showed their maximum abundance in those habit ats. Greatest avian diversity was found in 2 young forest types (6-20 yr following harvesting). Young, even-aged regeneration had the greate st abundance of individual birds per unit area, whereas mature hardwoo d had the lowest total abundance. Ten of 37 Neotropical migrant specie s had their highest abundance in the 2 youngest stages of forest (clea rcuts and regeneration) whereas 13 of 37 species had their highest abu ndance in the 3 mature forest types. Short-distance migrants had highe st abundances in early-successional habitats, and mature softwood stan ds contained the greatest number of resident species. The presence or absence at a point count station of 10 late-successional species (of 3 7) and 13 early-successional species (of 35) was related to the amount of similar habitat within 1 km of the point count center (homogeneous landscapes). Few species showed highest abundances in heterogeneous l andscapes. Spatially consolidating harvesting might enhance both early - and late-successional species simultaneously. Based on species-habit at associations identified in this study, estimated population trends in a 1,270 km(2) section of our study area did not correlate well with Breeding Bird Survey routes occur in the industrial forest of norther n Maine, and because of different trends in habitat abundances inside and outside of the study area. This result indicates there might be im portant subregional differences in landbird population trends. Current timber harvest rates likely will result in a decrease in abundance of mature forest in Maine's industrial forest. Many early-successional s pecies, including some of conservation concern, well benefit from this trend. Abundances of mature-forest species probably will decrease. Th e challenge industry and conservation biologists face is how to constr uct dynamic landscapes that balance the age-class distribution of the forest and maintain mature forest species.