CR 60:187-197 (2014)  -  DOI: https://doi.org/10.3354/cr01233

ABSTRACT: We examined the autumn migratory behavior of the common buzzard Buteo buteo from recoveries of 2157 ringed individuals across Europe over the last 50 yr, as well as from birds migrating through Sweden and Spain between 1976 and 2008. A generalized linear model analysis showed evidence of a shortening of the distance between areas of common buzzard breeding and wintering over the last 50 yr. The ability of common buzzard populations to shorten their migration distance was related to temperature anomalies in the Northern Hemisphere and depended on the breeding region, with northern European populations shortening their migration distance to the greatest extent. Changes in migratory distances were accompanied by no apparent shift in migratory direction. A significant reduction in the annual number of common buzzards migrating through the Strait of Gibraltar (Spain) occurred between 1976-1977 and 1999-2008. Similar decreases in the number of migrating common buzzards were observed in the annual passage at Falsterbo (Sweden) between 1975 and 2007. Furthermore, a quantile regression analysis of the time series record of migrating common buzzards at the strait revealed that median- and late-passage common buzzards crossed up to 7 d earlier in 2008 than in 1999. Shifts in migratory behavior in the European common buzzard may have ecological and evolutionary consequences for the different species of the genus Buteo in Europe, since the winter distribution of the steppe buzzard Buteo buteo vulpinus in central and eastern Europe appears to be affected by the distribution of common buzzards (B. b. buteo) from western Europe, which are extending their breeding range northwards.

KEY WORDS: Migration distance · Passage dates · Migration counts · Climate change · Habitat change