Monitoring Bird Populations on National Forest Lands: 1995

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 abundances and to eventually distinguish between larger-scale trends and small-scale shifts in abundance. Data collected from 1991 to 1995 or 1992 to 1995 have provided information on annual variation and trends over time for individual species and community parameters and relative abundance within representative cover types on the Forests. A total of 16 species (all Forests total) had significant linear trends during the monitoring period. The Great-crested Flycatcher, Blue Jay, Red and White-breasted Nuthatches, Veery, Brown Thrasher, Northern Parula, Chestnut-sided Warbler, Yellow-rumped Warbler, Canada Warbler, Swamp Sparrow, and Evening Grosbeak increased in abundance over all years; while the Hairy Woodpecker, Winter Wren, Red-eyed Vireo, and Indigo Bunting decreased in abundance over all years. The Red-eyed Vireo also had a decreasing trend in the Ottawa National Forest and decreased consistently in the Apostle Island National Lakeshore. No single explanation can be offered for a particular trend in annual variation; however; it is important to note that the monitoring activity has reached a state of longevity where trends 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. Results from the monitoring can be used to aid forest managers by providing information on bird/habitat associations within 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.