Birds of Indian Subcontinent

The Role of the Eurasian Sparrowhawk (Accipiter nisus) in the Decline of the House Sparrow (Passer domesticus) in Britain (Le rôle d'Accipiter nisus dans le déclin de Passer domesticus en Grande-Bretagne)

Publication Type:Journal Article
Year of Publication:2010
Authors:Bell, CP, Baker, SW, Parkes, NG, M. Brooke, deL, Chamberlain, DE
Journal:The Auk
Date Published:2010
ISBN Number:00048038
Keywords:Accipiter, Accipiter nisus, Accipitridae, Nisus, Passer, Passer domesticus, Passer montanus, Passeridae, United Kingdom
Abstract:Abstract We compared the pronounced geographic pattern in the recolonization of Britain by the Eurasian Sparrowhawk (Accipiter nisus) from 1970 onward with the spatiotemporal pattern among House Sparrow (Passer domesticus) populations over the same period, using data on the occurrence of both species at garden feeding stations. Using a simulation of House Sparrow population trends based on a logistic model that incorporated a predation index derived from Eurasian Sparrowhawk incidence functions, we generated a close approximation to the unique trajectories among House Sparrow populations in rural and urban sites in different regions of Britain. We carried out further comparisons using two contrasting methods that focused solely on temporal patterns. We used estimates of the varying date of Eurasian Sparrowhawk recolonization at different sites to derive time variables in relation to recolonization date. One such relative time variable proved to be a better predictor of House Sparrow numbers than chronological time; it indicated that House Sparrow numbers were generally stable or increasing prior to recolonization by Eurasian Sparrowhawks but declined continuously afterward. We also detected a significantly greater decrease in House Sparrow numbers when Eurasian Sparrowhawks were present using a method that compared annual changes in the abundance of prey species in the presence or absence of a predator. On the basis of these results, we argue that predation by Eurasian Sparrowhawks may be a sufficient explanation for the decline in House Sparrows in Britain. We also argue that urban House Sparrow populations' long-term release from predator pressure made them especially vulnerable when urban habitats were colonized by Eurasian Sparrowhawks. Received 3 April 2009, accepted 31 October 2009.
Short Title:The Auk
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith