Action: Control mammalian predators on islands for wildfowl
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.
The effectiveness assessment of the control of mammalian predators on islands was carried out across all bird species groups.
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’.