Monitoring Bird Populations on National Forest Lands: 1994

Abstract

A habitat specific bird monitoring program was established on the Chequamegon, Chippewa, and Superior National Forests in 1991 and 1992 (Chequamegon National Forest). The program was designed to assess annual differences in bird relative abundance, and to attribute changes in numbers to habitat changes on the forest, or to natural fluctuations in bird numbers. Data collected from 1991 to 1994 or 1992 to 1994 have provided information on annual variation among guilds and individual species, and on relative densities of species within representative cover types on the Forests. A total of ten species (all Forests total) showed significant trends during the monitoring period. The White and Red-breasted Nuthatches, Yellow-bellied Flycatcher, Alder Flycatcher, and Yellow-rumped Warbler increased in abundance over all years; while Swamp and Chipping Sparrows, Brown Creeper, Eastern Wood-Pewee, and Hairy Woodpecker decreased in abundance over all years. No simple explanation can be offered for a particular trend in annual variation; however, it is important to note that the monitoring activity is beginning to reach a state of longevity where trends are can be detected. Trends or lack thereof of trends will be useful in resolving potential problems within a National Forest or to support conclusions that a problem does not exist. This information can be used to aid forest management by providing information on forest cover types. Based on power analysis, a sufficient sampling regime is in place to detect reasonable changes in abundance for many forest birds, including many neotropical migrants.