Urban tree composition is associated with breeding success of a passerine bird, but effects vary within and between years.

Jensen, J. K., Ekroos, J., Watson, H., Salmon, P. , Olsson, P. and Isaksson, C. (2023) Urban tree composition is associated with breeding success of a passerine bird, but effects vary within and between years. Oecologia, 201(3), pp. 585-597. (doi: 10.1007/s00442-023-05319-8) (PMID:36681784) (PMCID:PMC10038977)

Abstract

Birds breeding in urban environments have lower reproductive output compared to rural conspecifics, most likely because of food limitation. However, which characteristics of urban environments may cause this deficiency is not clear. Here, we investigated how tree composition within urban territories of passerine birds is associated with breeding probability and reproductive success. We used 7 years of data of breeding occupancy for blue and great tits (Cyanistes caeruleus; Parus major) and several reproductive traits for great tits, from 400 urban nest boxes located in 5 parks within the city of Malmö, Sweden. We found that tits, overall, were less likely to breed in territories dominated by either non-native trees or beech trees. Great tit chicks reared in territories dominated by non-native trees weighed significantly less, compared to territories with fewer non-native trees. An earlier onset of breeding correlated with increased chick weight in great tits. Increasing number of common oak trees (Quercus robur) was associated with delayed onset of breeding in great tits. Notably, as offspring survival probability generally increased by breeding earlier, in particular in oak-dominated territories, our results suggest that delayed onset of breeding induced by oak trees may be maladaptive and indicate a mismatch to this food source. Our results demonstrate that tree composition may have important consequences on breeding success of urban birds, but some of these effects are not consistent between years, highlighting the need to account for temporal effects to understand determinants of breeding success and inform optimal management in urban green spaces.

• Item Type: Articles
• Additional Information: Open access funding provided by Lund University. The study was funded by a grant from the Swedish Research Council FORMAS to CI (grant 2016–00329). PO was funded by FORMAS (grant 2016‐00324).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Salmon, Dr Pablo
• Authors: Jensen, J. K., Ekroos, J., Watson, H., Salmon, P., Olsson, P., and Isaksson, C.
• College/School: College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
• Journal Name: Oecologia
• Publisher: Springer
• ISSN: 0029-8549
• ISSN (Online): 1432-1939
• Published Online: 21 January 2023
• Copyright Holders: Copyright © 2023 The Authors
• First Published: First published in Oecologia 201(3): 585-597
• Publisher Policy: Reproduced under a Creative Commons license