| Autor: |
Shutt JD; Institute of Evolutionary Biology, The University of Edinburgh, The King's Buildings, Edinburgh EH9 3FL, UK., Cabello IB; Institute of Evolutionary Biology, The University of Edinburgh, The King's Buildings, Edinburgh EH9 3FL, UK., Keogan K; Institute of Evolutionary Biology, The University of Edinburgh, The King's Buildings, Edinburgh EH9 3FL, UK., Leech DI; British Trust for Ornithology, The Nunnery, Thetford, Norfolk IP24 2PU, UK., Samplonius JM; Institute of Evolutionary Biology, The University of Edinburgh, The King's Buildings, Edinburgh EH9 3FL, UK., Whittle L; Woodland Trust, Kempton Way, Grantham, Lincolnshire NG31 6LL, UK., Burgess MD; RSPB Centre for Conservation Science, The Lodge, Sandy, Bedfordshire SG19 2DL, UK.; Centre for Research in Animal Behaviour, The University of Exeter, Exeter, Devon EX4 4QG, UK., Phillimore AB; Institute of Evolutionary Biology, The University of Edinburgh, The King's Buildings, Edinburgh EH9 3FL, UK. |
| Abstrakt: |
Establishing the cues or constraints that influence avian timing of breeding is the key to accurate prediction of future phenology. This study aims to identify the aspects of the environment that predict the timing of two measures of breeding phenology (nest initiation and egg laying date) in an insectivorous woodland passerine, the blue tit (Cyanistes caeruleus). We analyse data collected from a 220 km, 40-site transect over 3 years and consider spring temperatures, tree leafing phenology, invertebrate availability and photoperiod as predictors of breeding phenology. We find that mean night-time temperature in early spring is the strongest predictor of both nest initiation and lay date and suggest this finding is most consistent with temperature acting as a constraint on breeding activity. Birch budburst phenology significantly predicts lay date additionally to temperature, either as a direct cue or indirectly via a correlated variable. We use cross-validation to show that our model accurately predicts lay date in two further years and find that similar variables predict lay date well across the UK national nest record scheme. This work refines our understanding of the principal factors influencing the timing of tit reproductive phenology and suggests that temperature may have both a direct and indirect effect. |
