Impacts of birds of prey on gamebirds in the UK: a review

Abstract

The influence of predators on the distribution, density and dynamics of their prey species has long been of interest to ecologists and wildlife managers. Where the prey population is also utilized by humans, conflicts may arise through competition for a limited resource. Because gamebird shooting in the UK provides employment, recreation and income, the impact of birds of prey on gamebird populations has been the subject of intense debate for many years. Various approaches have been used to assess the impacts that raptors have on gamebird populations. Here we review the applicability and limitations of the methods used and assess the scientific evidence for population-level and economic impacts of raptors on gamebird populations in the UK. Raptors may, in some situations, take large numbers of gamebirds and may be an important proximate cause of mortality, although few studies have addressed the impacts of raptors on either breeding or pre-shooting densities. Two exceptions are studies of Hen Harrier Circus cyaneus , Peregrine Falcon Falco peregrinus predation on Red Grouse Lagopus lagopus scoticus on moorland in Scotland and Sparrowhawk Accipiter nisus predation on Grey Partridge Perdix perdix on farmland in England. Both these studies suggested that raptors could have population-level impacts when their gamebird prey was already at low density. Studies on predation of captively bred gamebirds suggest that numbers taken by raptors at release pens vary considerably and in a few cases raptors have been documented killing relatively large numbers. On the whole, however, it appears that raptors account for a relatively small proportion of mortality among released birds and the impact on subsequent shooting bags is unknown. We summarize important gaps in current knowledge and recommend specific areas for future research.

Declining reproductive output in capercaillie and black grouse – 16 countries and 80 years

“…Moreover, our results might indicate that a recent change in chick survival is more likely to have occurred than changes in nest success for British and continental European black grouse, particularly because we do not see changes in broods per hen which is closely related to nest success. The relative importance of corvids to chick survival remains unclear, while the importance of raptors (Park et al, 2008;Tornberg et al, 2012) and mammalian predators (Marcström et al, 1988) is more certain.…”

Diet diversity of the Common Buzzard (Buteo buteo) in a vole-less environment

“…The strength of lethal effects is determined largely by predator abundance and proportion of the prey in the diet (Redpath 1991, Oro et al 2005, Valkama et al 2005, Park et al 2008. Non-lethal effects, both on the prey itself and indirectly on other trophic levels as a result of changes in prey density, may have a considerable role in shaping community dynamics (Preisser et al 2005, Cresswell 2008).…”

Conservation management of moorland: a case study of the effectiveness of a combined suite of management prescriptions which aim to enhance breeding bird populations

“…Predation by raptors can lead to reduced population densities of Red Grouse, Skylark and Meadow Pipit on moorland (Thirgood et al 2000, Amar et al 2008, Baines et al 2008, Park et al 2008. Breeding numbers of raptors and Short-eared Owl Asio flammeus actually decreased in the mitigation area during the ten-year study period (Appendix 1), with similar (or even more marked) declines elsewhere within the area (unpublished SPA monitoring data supplied by Scottish Natural Heritage).…”