Data from the Nest Record Scheme provide strong evidence of shifts towards earlier laying in a range of species, linked to climate change. We have now identified 44 species that, on average, are laying between 1 and 30 days earlier than in the mid 1960s. The species involved represent a wide range of taxonomic and ecological groups, including raptors (Kestrel – 8 days), waterbirds (Moorhen – 6 days), waders (Oystercatcher – 8 days), migrant insectivores (Pied Flycatcher – 11 days, Swallow – 8 days), resident insectivores (Robin – 8 days, Blue Tit – 11 days), corvids (Magpie – 30 days) and resident seed-eaters (Greenfinch – 16 days).
For some species these shifts towards earlier laying may be insufficient to track seasonal advances in food availability. Recent research has shown that significantly stronger phenological responses to climate change are displayed at lower than at higher trophic levels, increasing the potential for disjunction and resulting population declines (Thackeray et al. 2010).
This report should be cited as: Baillie, S.R., Marchant, J.H., Leech, D.I., Renwick, A.R., Eglington, S.M., Joys, A.C., Noble, D.G., Barimore, C., Conway, G.J., Downie, I.S., Risely, K. & Robinson, R.A. (2012) BirdTrends 2011. BTO Research Report No. 609. BTO, Thetford. http://www.bto.org/birdtrends