Les hommes ont oublié cette vérité. Mais tu ne dois pas l'oublier, dit le renard. Tu deviens responsable pour toujours de ce que tu as apprivoisé.
Le Petit Prince, chap. 21

Sunday, 7 July 2013

Escape behaviour related to different predators in urban or rural habitats

Møller, A. P., & Ibáñez-Álamo, J. D. (2012). Escape behaviour of birds provides evidence of predation being involved in urbanization. Animal Behaviour, 84 (2): 341–348

Altered predation risk in urban environments may contribute to animals becoming successfully urbanized by individuals from rural habitats. Escape behaviour has evolved to allow an individual to escape once captured by a predator. We tested whether altered predation risk in urban environments is associated with colonization of such habitats by comparing escape behaviour of 1132 individual birds belonging to 15 species from nearby rural and urban populations when captured by a human. Raptors (of which the Eurasian sparrowhawk, Accipiter nisus, was one of the most common species) were more common in rural than in urban habitats, whereas cats, Felis catus, showed the opposite pattern. There were consistent differences in escape behaviour between habitats, showing divergence in behaviour from the ancestral rural state. Urban birds wriggled less, showed higher tonic immobility, more often lost feathers, were less aggressive by biting less often, and emitted fear screams and alarm calls more often than rural birds. Furthermore, differences in escape behaviour between habitats were related to susceptibility to predation by sparrowhawks, as expected if differences in behaviour were due to differences in predation risk. Finally, an analysis of differences in escape behaviour between rural and urban birds revealed a significant relationship with time since urbanization, suggesting that escape behaviour has changed in urban environments over time. These findings suggest that release from predation and change in predator community associated with urbanization has altered the antipredator behaviour of birds colonizing towns and cities.


► We investigated escape behaviour of urban and rural birds. ► Urban birds tried to escape less actively and gave more alarm calls than rural birds. ► These differences were related to susceptibility to predation by sparrowhawks. ► The degree of divergence was related to time since urbanization. ► Predation is an important selection force driving adaptation to urban habitats.

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