Recent trends in counts of migrant hawks from northeastern North America

摘要: Using simple regression, pooled-sites route-regression, and nonparametric rank-trend analyses, we evaluated trends in counts of hawks migrating past 6 eastern hawk lookouts from 1972 to 1987. The indexing variable was the total count for a season. Bald eagle (Haliaeetus leucocephalus), peregrine falcon (Falco peregrinus), merlin (F. columbarius), osprey (Pandion haliaetus), Cooper's (Accipiter cooperii) increased using route-regression methods (P 0.10). We found no consistent > 0.10) sharp-shinned (A. striatus), northern goshawks gentilis), red-shouldered (Buteo lineatus), red-tailed (B. jamaicensis), rough-legged lagopus), American kestrels sparverius). Broad-winged platypterus) declined < 0.05) based on method. Empirical comparisons our results with those well-studied species such as falcon, bald eagle, indicated agreement nesting surveys. suggest that migrant are useful economical method detecting long-term across regions, particularly otherwise cannot be easily surveyed. J. WILDL. MANAGE. 54(3):463-470 Wildlife managers have responsibilities monitor wider variety wildlife than past, cost-effective efficient needed detect populations might warrant management action. Monitoring raptors over large areas is difficult because most occur low densities, some secretive or nest remote (Fuller Mosher 1987). Although season surveys been used endangered (Cade et al. 1988), expensive labor intensive. Most other received less study their breeding grounds. However, migratory counted annually during migrations at certain concentration points United States (e.g., Broun 1935, Allen Peterson 1936). Ward Berry (1972) suggested provide population trends. Assuming data can numbers migrants these reliable index populations, then analyses could raptor management. Qualitative infer declines, increases, stability Nagy 1977, Dunne Sutton 1986). usefulness "eyeball" quality which they questioned Kerlinger 1985). Hussell (1985) quantitative allay previous criticisms use migration data, Titus (1989a, 1990) Bednarz (1989) discussed analyzing data. Svensson (1978) others Indeed, policy decisions about U.S. Dep. Inter. 1983) status raptors. Our objective estimate 14 regression techniques single-site compare information available studies. thank observers who Data collection supported, part, by Office Migratory Bird Management (OMBM), Fish Service, through contracts Cape May Observatory, Derby Hill Observatory-Onondaga Audubon Society, Whitefish Point Duluth Society. Hawk Mountain Sanctuary Association (L. 'Present address: Alaska Department Game, Division Conservation, P.O. Box 20, Douglas, AK 99824.