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Providing evidence to improve practice

Action: Control predators not on islands for seabirds Bird Conservation

Key messages

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Supporting evidence from individual studies


A before-and-after study at a common tern Sterna hirundo colony in eastern Canada (Guillemette & Brousseau 2001) found that fledging success was higher in 1994 when chick-predating gulls (four herring gulls Larus argentatus and one great black-backed gull Larus marinus) were selectively shot, compared with 1993 and 1995, when no gulls were culled (16% of 115 eggs fledged vs. no chicks fledging from 165 eggs).



A before-and-after study at three sites in northern North Island, New Zealand (Wilson & Hansen), found that the population of New Zealand fairy terns Sterna nereis davisae increased from a low of five breeding pairs in 1987 and an annual decline of 1.5% to between 35 and 40 individuals in 2005 and an annual increase of 1.4%, following the continual trapping of introduced mammalian predators (feral cats Felis catus, hedgehogs Erinaceus europaeus, stoats Mustela erminia, ferrets M. putorius, weasels M. nivalis, Australian brush-tailed possums Trichosurus vulpecula and rats Rattus spp.) from 1992 onwards. On average 100 hedgehogs and 12 cats were trapped each year.


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.