Action Synopsis: Bird Conservation About Actions

Control mammalian predators on islands

How is the evidence assessed?
  • Effectiveness
  • Certainty
  • Harms

Study locations

Key messages

The assessment of the effectiveness of this intervention was based on a total of 33 studies across all species groups. See Background section below for links to the evidence for the control of mammalian predators on islands on specific species groups.

A paired sites study from Finland and a literature review from the UK found increased bird species richness and abundance or population recoveries and recolonisations, following the control or eradication of mammalian predators.

  • Predators removed included American mink Mustela vison, rats Rattus spp. pigs Sus scrofa, cats Felis catus, dogs Canis familiaris and grey fox Dusicyon griseus.



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 paired sites before-and-after study on four paired study areas (72-139 km2) of >60 small islands in Archipelago National Park, southwest Finland (Nordstrom & Korpimaki 2004) found that, following the removal of up to 63 introduced and predatory American mink Mustela vison each year in 1992-3 and 1998, experimental areas had significantly higher species richness and abundance, compared to control areas. There was a significant positive relationship between the degree of isolation of the islands and species richness and abundance in control, but not experimental areas. In all areas, larger islands had more pairs and more species.

    Study and other actions tested
  2. A 2010 literature review (Hilton & Cuthbert 2010) found that all five successful invasive mammal eradication and control programmes on United Kingdom Overseas Territories found native bird population recoveries and/or recolonisations following the programmes. Recovering species included seabirds and songbirds. The impacts of ten more eradication programmes have not been recorded or published, whilst a final eradication attempt (in the British Indian Ocean Territories) failed to remove black rats Rattus rattus. Eradicated/controlled species included pigs Sus scrofa, cats Felis catus, rats Rattus spp., dogs Canis familiaris and grey fox Dusicyon griseus.

    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
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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.

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