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

Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
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How is the evidence assessed?

Effectiveness

45%
Certainty

6%
Harms

0%

Calculating overall effectiveness category

Background information and definitions

If the wild populations of a species are very small then it may not be possible to foster offspring to conspecifics. However, it may be possible to foster chicks and eggs to a similar, but more abundant species, if one is present. This can increase the reproductive output of the wild population of the endangered species, or even allow for the reintroduction of a population into parts of its former range.

Study locations

Key messages

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.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

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.
Study and other actions tested
Referenced paper
Byrd G.V., Sincock J.L., Telfer T.C., Moriarty D.I. & Brady B.G. (1984) A cross-fostering experiment with Newell's race of Manx shearwater. Journal of Wildlife Management, 48, 163-168.

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. (2020) Bird Conservation. Pages 137-281 in: W.J. Sutherland, L.V. Dicks, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2020. Open Book Publishers, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

This Action forms part of the Action Synopsis:

Bird Conservation

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Actions	Effectiveness	Studies	Category
Foster eggs or chicks of petrels and shearwaters with wild non-conspecifics (cross-fostering) Action Link	Unknown effectiveness (limited evidence)	1	Synopsis Link
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