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Urban Areas as Ecological Traps: Studying Great Tits Parus Major Along an Urbanisation Gradient

出版	Universiteit Antwerpen, 2016
URL	http://books.google.com.hk/books?id=P9KoswEACAAJ&hl=&source=gbs_api

註釋Many studies have reported negative effects of urbanisation on bird breeding success, with the role of food thought to play a particularly significant role. The negative effects of city environments on birds have lead researchers to suggest that urban areas may represent ecological traps, whereby individuals settle preferentially in urban habitats but show poor reproductive success relative to other available rural habitats. In this context, this thesis sought to test the effects of urbanisation measured at two spatial scales on both the breeding success of great tits Parus major, and its food during the breeding season. A nested design was used in study sites in northern Belgium with a priori quantified degrees of urbanisation at both local and regional scales. Results found breeding success to vary at one or both spatial scales of urbanisation for all measured parameters: in urban areas great tits displayed advanced laying dates and breeding success was lower than in rural areas, with smaller clutch sizes, lower nestling masses and fewer fledglings per egg. Results regarding food showed that the proportion of caterpillars provisioned to nestlings varied with local scale urbanisation, with significantly lower proportions of caterpillars provisioned to nestlings in urban areas. Moreover, the proportion of caterpillars provisioned was found to have a significant positive effect on nestling mass. Provisioning rates and caterpillar lengths were not found to vary with urbanisation. Results of this study suggest that food quality plays a key role in breeding success in cities, highlight the importance of utilising multiple spatial scales in analysing urbanisation effects, and ultimately provide support to the ecological trap hypothesis.