Conservation Evidence strives to be as useful to conservationists as possible. Please take our survey to help the team improve our resource.

Providing evidence to improve practice

Action: Control mammalian predators on islands for wildfowl Bird Conservation

Key messages

Read our guidance on Key messages before continuing

A before-and-after study from Alaska found that cackling geese Branta hutchinsii returned to a total of eight nesting islands between the 1970s and 1991, following the removal of Arctic foxes Alopex lugopus from the islands.

Supporting evidence from individual studies


A before-and-after study from the Aleutian Islands, Alaska, USA on the cackling goose Branta hutchinsii recovery programme (USFWS 2001) found that geese bred on four islands from 1984 onwards after Arctic foxes Alopex lugopus were eradicated from them. Together with releases of captive-bred individuals, the programme resulted in the population increasing to 6,000 birds by 1991, compared with fewer than 1,000 in the 1970s, and birds were breeding on eight fox-free islands. The effects of different release techniques are discussed in ‘Release captive-bred individuals into the wild to restore or augment wild populations’, ‘Release birds as adults or subadults, not juveniles’ and ‘Clip birds’ wings on release’.


Referenced papers

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. (2019) Bird Conservation. Pages 141-290 in: W.J. Sutherland, L.V. Dicks, N. Ockendon, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2019. Open Book Publishers, Cambridge, UK.