Control mammalian predators on islands for gamebirds

Overall effectiveness category Awaiting assessment
Number of studies: 1
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Effectiveness

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Calculating overall effectiveness category

Background information and definitions

The effectiveness assessment of the control of mammalian predators on islands was carried out across all bird species groups.

Study locations

Key messages

A single replicated and controlled study on two Swedish islands found that four species of gamebirds had larger broods, and more females had chicks, when predators were controlled. Two of the species also showed population-level responses.

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

A replicated, controlled study on two islands (18 km² and 23.5 km²) in the Gulf of Bothnia, Sweden between 1976 and 1984 (Marcstrom et al. 1988) found that gamebird brood sizes were significantly larger and a higher proportion of females had chicks over a four year period when predators were controlled, compared to when predators were not removed (with predator control: 5.5 chicks/brood, 77% of 378 hens had chicks; without predator control: 3.3 chicks/brood, 59% of 314 hens had chicks). . Species studied were capercaillie Tetrao urogallus, black grouse Tetrao tetrix, hazel grouse Bonasa bonasia and willow ptarmigan Lagopus lagopus, with adult capercaillie and black grouse counts increasing by 56-80% after predators had been controlled for two years, and counts at leks increasing by 166-174%. Predators (European pine martins Martes martes and red foxes Vulpes vulpes) were trapped and shot.
Study and other actions tested
Referenced paper
Marcstrom V., Kenward R.E. & Engren E. (1988) The impact of predation on boreal tetraonids during vole cycles: an experimental study. Journal of Animal Ecology, 57, 859-872.

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

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This Action forms part of the Action Synopsis:

Bird Conservation

Related Actions

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Control mammalian predators on islands for songbirds Action Link	Awaiting assessment	5	Synopsis Link
Control mammalian predators on islands Action Link	Beneficial	2	Synopsis Link
Control mammalian predators on islands for pigeons Action Link	Awaiting assessment	2	Synopsis Link