Centre for Ornithology, University of Birmingham

Does supplementary feeding of garden birds improve breeding performance?

Research students Tim Harrison and Jen Smith at the Centre for Ornithology, University of Birmingham, are working in collaboration with the British Trust for Ornithology (BTO) and CJ Wildlife to examine the effects of food supplementation on avian reproductive performance.

This research has considerable applied implications, since the feeding of birds in UK gardens is common and growing evermore popular. Influential organisations such as the Royal Society for the Protection of Birds (RSPB) now recommend that garden birds should be fed all year round, not just during winter as has historically been more common. Our research is designed to assess the importance bird feeding during the spring and early summer by comparing the reproductive performance of fed and unfed garden birds.

From an applied perspective, it would be preferable to conduct such a study in a garden environment. This presents many problems, however, not least controlling the amount and quality of food being supplemented, both within and outside of the study area. With this in mind, our research is being conducted within a 101-hectare woodland in Worcestershire, UK. This woodland acts as a self-contained study site for the different dietary treatments. Our focal species are Blue Cyanistes caeruleus and Great Parus major Tits, that nest in the 292 nestboxes erected at the wood in autumn 2005. Short-term measures of reproductive success (e.g. clutch size and nestling condition) are being combined with longer-term measures (e.g. fledgling survival to the autumn). This study will continue until 2009.

Our research is being funded by the Natural Environment Research Council (NERC). All field-equipment has been generously provided by CJ Wildlife. We are grateful to the Worcestershire Wildlife Trust, and bird ringers of the Birmingham University Ringing Group, especially Mr Bert Coleman, Miss Leigh Nash and Mr Tony Kelly. Academic supervisors of this research are Dr Jim Reynolds & Prof. Graham Martin (University of Birmingham), Dr Dan Chamberlain & Dr Dave Leech (BTO), and Dr Stuart Bearhop (Queens University Belfast).