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Predation of red squirrels by northern goshawks in a conifer forest in northern England: Can this limit squirrel numbers and create a conservation dilemma?

Lookup NU author(s): Dr Peter Lurz, Professor Stephen Rushton

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Abstract

Red squirrels (Sciurus vulgaris) have been lost from most broadleaved habitats in England due to the range expansion of grey squirrels (S. carolinensis). Currently, the main refugia for red squirrels in England are the extensive exotic conifer forests in the north. These forests are also home to an expanding population of northern goshawks (Accipiter gentilis) that were re-established in the 1970s. During the breeding season (March - August), goshawks feed mainly on birds, with species of Columbidae, Corvidae and Phasianidae/Tetraonidae comprising 79% of 5445 prey items collected during 1973-1996. Only 97 red squirrels were recorded in this sample. We estimated that ca. 79 red squirrels were removed by goshawks each breeding season in Kielder Forest, but there was much annual variation (8-261 squirrels predated) that appeared to be related to the masting frequency of Norway spruce (Picea abies). Goshawks were likely to remove fewer squirrels outside the breeding season (September-February) because only adult males overwintered in the study area. Based on the area of conifers of a cone-bearing age and known densities of squirrels, we estimated that 1294-5556 adult squirrels produced 2135-9167 offspring annually in Kielder. For goshawks to reduce the population growth rate of squirrels to zero, predation would have to exceed 50% of the population. Clearly, this does not appear to be the case. This conclusion is in broad agreement with other studies indicating that food availability (conifer seed) is the main factor limiting numbers of tree squirrels, not predation. Thus, existing conservation management for sympatric populations of red squirrels and goshawks are compatible. © 2002 Elsevier Science Ltd. All rights reserved.

Publication metadata

Author(s): Petty S, Lurz PWW, Rushton SP

Publication type: Article

Publication status: Published

Journal: Biological Conservation

Year: 2003

Volume: 111

Issue: 1

Pages: 105-114

Print publication date: 01/05/2003

ISSN (print): 0006-3207

ISSN (electronic): 1873-2917

Publisher: Elsevier BV

URL: http://dx.doi.org/10.1016/S0006-3207(02)00254-9

DOI: 10.1016/S0006-3207(02)00254-9

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