This study suggests that avian morphs may allocate/partition foraging activity by weather conditions/habitat, which maximise their concealment from prey.Ĭolouration has been widely recognised to play an important role in a variety of ecological processes, from camouflage (crypsis) 1 to intraspecific communication 2 and mate choice 3, all of which are likely to be under considerable selective pressure from both natural and sexual selection 4. Our results may also help explain why dark-morphs predominate in this study region, which experiences high rainfall and lower light-levels during the breeding-period. This suggests that different morphs may be better adapted to foraging under different light-conditions, potentially playing a role in maintaining colour polymorphism in this species.
Furthermore, we found differential-degrees of habitat selection, with dark-morphs selecting more enclosed habitats compared to white-morphs. As predicted, we found that light-levels influenced foraging behaviour in different ways for morphs: Dark-morphs showed a decrease in foraging with increasing light-levels whereas no relationship was found for white-morphs. We use GPS-tracking data to contrast the foraging behaviour and habitat selection of morphs. We explore this hypothesis in a polymorphic raptor, the black sparrowhawk Accipiter melanoleucus, which exhibits a discrete dark and white-morph. The mechanism for this advantage is proposed to be through enhanced crypsis via background-matching. One hypothesis proposes that different morphs are adapted to different ambient light conditions, with lighter morphs having a selective advantage in bright conditions and darker morphs having advantages in darker conditions.
Colour polymorphism may be maintained within a population by disruptive-selection.
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