Figure 17.1 Locations of Sparrowhawks Accipiter nisus ringed as chicks and recovered in a later breeding season, shown in relation to natal site (centre). Recoveries came from all sectors of the compass and declined in density with increasing distance from the hatching site. From Newton (1979).
Among north European raptors, for example, a circle drawn at 50 km radius around the birthplace would include 98% of the breeding season recoveries of Eurasian Sparrowhawks Accipiter nisus, 95% of Common Buzzards Buteo buteo, 89% of Common Kestrels Falco tinnunculus, 75% of Merlins Falco columbarius, 71% of Northern Goshawks Accipiter gentilis and 43% of Ospreys Pandion haliaetus (Newton 1979).
Within species, the settling pattern may differ somewhat from year to year or from region to region, depending on circumstances, including the density of the population and the patchiness of habitat in the region concerned (for European Pied Flycatcher Ficedula hypoleuca, see Sokolov 1997; for Long-tailed Tit Aegithalos caudatus, see Russell 1999; for Blue Tit Parus caeruleus and Great Tit P. major, see Matthysen et al. 2001). Some small forest species are reluctant to cross open land. Blackwell & Dowdeswell (1951) described how a playing field just 130 m wide presented a barrier to local movements of Blue Tits so that their ringed study
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