Integrated behavioural and stable isotope data reveal altered diet linked to low breeding success in urban-dwelling blue tits (Cyanistes caeruleus)

Pollock, C., Capilla-Lasheras, P. , McGill, R. A.R. , Helm, B. and Dominoni, D. M. (2017) Integrated behavioural and stable isotope data reveal altered diet linked to low breeding success in urban-dwelling blue tits (Cyanistes caeruleus). Scientific Reports, 7, 5014. (doi: 10.1038/s41598-017-04575-y) (PMID:28694437) (PMCID:PMC5503996)

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Animals often show reduced reproductive success in urban compared to adjacent natural areas. The lower availability and quality of natural food in cities is suggested as one key limiting factor. However, only few studies have provided conclusive support by simultaneously assessing food availability, diet and fitness. We consolidate this evidence by taking a holistic approach, comparing blue tits breeding in forest, suburban and urban areas. We (a) assessed arthropod availability, (b) investigated parental provisioning behaviour, (c) inferred diet through stable isotope analysis, and (d) measured reproductive success. At the urban site, we found a significant reduction in caterpillar availability, the main food source of blue tits, and consequently urban tits fed their offspring with fewer caterpillars than forest and suburban birds. Stable isotope analysis confirmed that diet in the urban area was fundamentally different than in the other sites. Reproductive success was lower in both urban and suburban sites compared to the forest site, and was positively associated with volume of provisioned caterpillars. Our findings provide strong integrative evidence that urban blue tit nestlings are not receiving a suitable diet, and this may be an important limiting factor for urban populations of this and potentially many other species.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Capilla Lasheras, Dr Pablo and Helm, Dr Barbara and Dominoni, Dr Davide and McGill, Dr Rona
Authors: Pollock, C., Capilla-Lasheras, P., McGill, R. A.R., Helm, B., and Dominoni, D. M.
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
Journal Name:Scientific Reports
Publisher:Nature Research
ISSN (Online):2045-2322
Copyright Holders:Copyright © 2017 The Authors
First Published:First published in Scientific Reports 7:5014
Publisher Policy:Reproduced under a Creative Commons License

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