Foster eggs or chicks of cranes with wild conspecifics

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

Effectiveness

26%
Certainty

11%
Harms

0%

Calculating overall effectiveness category

Background information and definitions

Natural variations in reproductive output can be detrimental when populations are very small, for example if pairs fail to produce fertile eggs or some pairs repeatedly fail to raise offspring successfully. One way to minimise this problem is to foster eggs and chicks between nests. Eggs and chicks from nests with more offspring than they are likely to be able to raise can be moved to those with infertile eggs. Alternatively, if a pair produces fertile eggs or healthy chicks but consistently fails to raise chicks then it may be possible to transfer offspring to a more successful pair.

In other circumstances it may be possible to foster chicks with other species (‘cross-fostering’). Studies describing this intervention are discussed in the following section ‘Foster eggs or chicks with wild non-conspecifics (cross-fostering).’

Study locations

Key messages

A small study in Canada found high rates of fledging for whooping crane Grus americana eggs fostered to first time breeders (which normally have very low fertility).

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 small study between 1986 and 1991 (Kuyt 1996) found that at least three ‘novice’ breeding pairs of whooping cranes Grus americana in a population in Northwest Territories and Alberta, Canada, successfully raised chicks when their own eggs were substituted for other eggs which were definitely fertile. Novice pairs normally have lower reproductive success than more experienced pairs. At least one pair with low breeding success was also provided with a fertile egg several days from hatching and successfully raised the chick. This study is also discussed in ‘Use captive breeding to increase or maintain populations’, ‘Release captive-bred individuals’ and ‘Foster eggs or chicks with wild non-conspecifics (cross-fostering)’.
Study and other actions tested
Referenced paper
Kuyt E. (1996) Reproductive manipulation in the whooping crane Grus americana. Bird Conservation International, 6, 3-10.

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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