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Providing evidence to improve practice

Action: Foster eggs or chicks of petrels and shearwaters with wild non-conspecifics (cross-fostering) Bird Conservation

Key messages

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A replicated and partially controlled study from Hawaii found that Newell’s shearwater Puffinus newelli eggs fostered to wedge-tailed shearwater P. pacificus nests had high fledging rates.


Supporting evidence from individual studies


A replicated partially controlled study at two sites on Kaua’i, Hawaii, USA, in 1978-80 (Byrd et al. 1984) found that Newell’s shearwater Puffinus newelli (formerly P. puffinus newelli) eggs transferred to wedge-tailed shearwater P. pacificus had high hatching and fledging rates, with an average of 74% of 90 fostered eggs producing a fledgling. This is similar to the highest recorded rates for Manx shearwaters P. puffinus and slightly higher than those of wedge-tailed shearwaters. The main cause of mortality was egg predation by introduced common mynas Acridotheres tristis, with only one chick being evicted by foster parents. Fostered chicks were slightly heavier and larger than Newell’s shearwaters raised by their natural parents. Data was not available on the return rates or breeding success of fostered chicks.


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.