Action Synopsis: Bird Conservation About Actions

Control predators not on islands for gamebirds

How is the evidence assessed?
  • Effectiveness
    not assessed
  • Certainty
    not assessed
  • Harms
    not assessed

Study locations

Key messages


About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

  1. A replicated, controlled study in the spring of 1974 on a cereal farm in Villers-Cotterêts, France (Westerskov 1997), found that grey partridges Perdix perdix were significantly more abundant in areas provided with ‘partridge cafeterias’ than in control areas. These ‘cafeterias’ included stoat Mustela ermine box-traps. This study is discussed in ‘Provide supplementary food to increase adult survival’.

    Study and other actions tested
  2. A replicated study (Baines 1996) at five sites in northern England and Scotland, found that densities and breeding success of black grouse Tetrao tetrix was no higher on moors with a gamekeeper (and associated predator control) than on moors without a game keeper (average of 1.6 males/km2, 2.3 females/km2 and 1.8 chicks/female on 11 keepered moors vs. 1.9 males/km2, 2.7 females/km2 and 1.9 chicks/female on nine unkeepered moors, n = 9). Moors were an average of 50 km2.

    Study and other actions tested
  3. A replicated, controlled study at two farmland and woodland sites in southern England between 1985 and 1990 (Tapper et al. 1996) found that grey partridge Perdix perdix breeding success and brood sizes were significantly higher when predators were controlled, compared to years without removal. This led to August partridge numbers being 75% higher and breeding numbers the next year being 36% higher. Over three years this led to breeding densities that were 2.6 times greater when predators were removed. Predators removed through trapping and shooting were predominantly red foxes Vulpes vulpes, carrion crows Corvus corone and black-billed magpies Pica pica.

    Study and other actions tested
  4. A controlled before-and-after study years in northern Scotland between 1989 and 1999 (Summers et al. 2004) found that the breeding productivity of western capercaillie Tetrao urogallus and ‘survival’ rates of 48 artificial nests were higher during the last three years (1994-6) of predator removal, compared to nine sites without predator removal. However, in the previous two years of predator removal (1992-3) and years without removal (1989-91, 1997-9), productivity was lower on the experimental site. In non-removal years, productivity averaged 0.1 chicks/female, compared with 1.4 chicks/female in removal years. Predator removal involved trapping carrion crows Corvus corone (a total of 368) and shooting red foxes Vulpes vulpes (a total of 22 adults and 52 cubs).

    Study and other actions tested
  5. A controlled study in 2002-9 on mixed farmland in Hertfordshire, England (Aebischer & Ewald 2010), found that the number of grey partridges Perdix perdix increased significantly on an experimental site, where predators were controlled (along with several other interventions), but only slightly on a control site without predator control. This increase was apparent in spring (from fewer than 3 pairs/km2 in 2002 to 12 pairs/km2 in 2009, with a high of 18 pairs/km2 vs. approximately 1 pair/km2 on the control site in 2002, increasing to approximately 4 pairs/km2 in 2009) and autumn (from fewer than 10 birds/km2 in 2002 to approximately 65 birds/km2 in 2009, with a high of 85 birds/km2 vs. approximately 4 birds/km2 on the control site in 2002, increasing to approximately 15 birds/km2 in 2009). Predators controlled were red fox Vulpes vulpes, stoats Mustela erminea, brown rats Rattus norvegicus, carrion crows Corvus corone and black-billed magpies Pica pica. The experimental site also had supplementary food provided and habitat creation (see ‘Provide supplementary food to increase adult survival’ and ‘Plant wild bird seed or cover mixture’). The effects of agri-environment schemes and the provision of set-aside are also discussed in ‘Pay farmers to cover the costs of conservation measures’ and ‘Provide or retain set-aside’.

    Study and other actions tested
Please cite as:

Williams, D.R., Child, M.F., Dicks, L.V., Ockendon, N., Pople, R.G., Showler, D.A., Walsh, J.C., zu Ermgassen, E.K.H.J. & Sutherland, W.J. (2020) Bird Conservation. Pages 137-281 in: W.J. Sutherland, L.V. Dicks, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2020. Open Book Publishers, Cambridge, UK.


Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

Bird Conservation

This Action forms part of the Action Synopsis:

Bird Conservation
What Works 2021 cover

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 21

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.

Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape ProgrammeRed List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Mauritian Wildlife Supporting Conservation Leaders
Sustainability Dashboard National Biodiversity Network Frog Life The international journey of Conservation - Oryx Cool Farm Alliance UNEP AWFA Bat Conservation InternationalPeople trust for endangered species Vincet Wildlife Trust