AVIS-IBIS

Birds of Indian Subcontinent

Potential impact of grey squirrels Sciurus carolinensis on woodland bird populations in England

Publication Type:Journal Article
Year of Publication:2010
Authors:Newson, S, Leech, D, Hewson, C, Crick, H, Grice, P
Journal:Journal of Ornithology
Volume:151
Issue:1
Date Published:2010
ISBN Number:2193-7192
Keywords:Columbidae, Merula, Streptopelia, Streptopelia decaocto, Turdidae, Turdus, Turdus maximus, Turdus merula
Abstract:Several woodland bird species have declined markedly in abundance in England over the past 40 years, whilst the grey squirrel Sciurus carolinensis , a non-native nest predator, has increased. Given the timing, there has been concern that grey squirrels have driven these declines, although there is little data to support this view. Using novel analytical methods and extensive national bird and grey squirrel monitoring data, we examine whether there is evidence that woodland bird populations in England have been depressed by grey squirrels and whether there is a relationship between nest failure and squirrel numbers. Our results indicate that grey squirrels are very unlikely to have driven observed declines of woodland birds in recent years, although the number of associations, positive as well as negative, between grey squirrels and woodland birds is greater than expected by chance. For this reason, we cannot exclude the possibility that the populations of a small number of bird species, principally increasing species, have been depressed to some degree at sites where a greater number of grey squirrels were present. Of these species, perhaps the most convincing evidence is for Common Blackbird Turdus merula and Eurasian Collared Dove Streptopelia decaocto where nest record data also identified a positive relationship between nest failure at the egg stage and squirrel abundance.
URL:http://dx.doi.org/10.1007/s10336-009-0445-8
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith