Impacts of Non-Native Species

Introductions of non-native mammals to islands have had major negative impacts on the resident colonies of ground-nesting seabirds.  Mammals such as brown rat (Rattus norwegicus) and American mink (Mustela vison) predate on seabird eggs, chicks and in some cases, adult birds.

Predation by mammals has caused the extinction of some colonies of ground-nesting seabirds such as terns, gulls, storm-petrels, Manx shearwater and Atlantic puffin.  Other colonies have been substantially depleted, with seabirds confined to breeding in places that are inaccessible to predators.  

The pressure from non-native mammals can be eliminated through management:

a) Eradication of non-native mammals from islands has resulted in the expansion of existing seabird colonies and in re-colonisation by seabird species.

b) Quarantine measures can prevent the invasions of islands by non-native mammals.

To date, piecemeal management has been carried out, but a more strategic approach would achieve the greatest conservation gains for seabirds and make more efficient use of resources.


Further Reading

1 Mitchell, P.I. & Ratcliffe, N. 2007. Abundance & distribution of seabirds on UK islands – the impact of invasive mammals. In Proceedings of the conference on Tackling the problem of invasive alien mammals on seabird colonies – Strategic approaches and practical experience. Edinburgh 2007. The National Trust for Scotland, Royal Zoological Society of Scotland and Central Science Laboratory.

2 Capizzi, D., Baccetti N. &  Sposimo, P. 2010. Prioritizing rat eradication on islands by cost and effectiveness to protect nesting seabirds. Biological Conservation 143 (2010) 1716–1727.

3 Ratcliffe, N., Mitchell, I., Varnham, K., Verboven, N. & Higson, P. 2009. How to prioritize rat management for the benefit of petrels: a case study of the UK, Channel Islands and Isle of Man. Ibis (2009), 151, 699–708.