Recent changes in body weight and wing length among some British passerine birds

摘要: We tested the prediction that global warming has caused recent decreases in body weight (Bergmann's rule) and increases wing length (Allen's 14 species of passerine birds at two localities England: Wicken Fen (1968-2003) Treswell Wood (1973-2003). Predicted long-term linear residual occurred four species: dunnocks (Wicken Fen), great tits, blue tits bullfinches (Treswell Wood). Non-linear also reed warblers blackcaps Fen, which had a surprising increase blackbirds. Residual lengths increased linearly, as predicted, six seven Fen. Whereas there were non-linear wrens, blackbirds Wood. Unexpected willow chaffinches The most parsimonious explanation for such changes is warming, predicted by Bergmann's rule. Greater site species-specific effects on (e.g. plus shorter wings woodland habitat) suggest less straightforward conclusion concerning Allen's rule, probably because involved variation both bone feather growth. Changes weights often differed between sometimes non-linear, perhaps reflecting short-term modifications selection pressures. Human-induced influences are discussed, avian predator population densities land-use change. Short-term temperature little effect, but rainfall did explain unusual blackbird weight, possibly result improving food (earthworm) availability.