Action Synopsis: Bird Conservation About Actions

Foster eggs or chicks of owls with wild conspecifics

How is the evidence assessed?
  • Effectiveness
  • Certainty
  • Harms

Study locations

Key messages

  • A replicated study in the USA found high fledging rates for barn owl Tyto alba chicks fostered to wild pairs.
  • A replicated controlled study from Canada found that captive-reared burrowing owl Athene cunicularia chicks fostered to wild nests did not have significantly lower survival or growth rates than wild chicks.



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

  1. A replicated study in Utah, USA (Marti & Wagner 1980), found that eight of ten barn owl Tyto alba chicks fostered to wild owl pairs in 1978 fledged successfully, with one male being confirmed as breeding in 1979, 60 km from the fledging site. Six young (all of which fledged) were placed in existing broods, with either one or two chicks in each, and four chicks were used to replace a clutch of four infertile eggs (two of these later died after falling from the nest).

    Study and other actions tested
  2. A replicated, controlled trial in mixed grasslands in Saskatchewan, Canada, in 2001-3 (Poulin et al. 2006), found that captive-reared burrowing owl Athene cunicularia chicks fostered to wild nests appeared to have lower survival rates than their wild foster siblings, but that this difference was not significant (six of nine foster owls died before migration vs. two of nine wild chicks). There were no differences in growth rates between wild chicks and captive chicks fostered at two to four days after hatching, three weeks after hatching or six weeks after hatching. In total, 54 birds were fostered, but not all could be monitored. Foster parents were supplied with one dead mouse a day for each fostered chick in their brood. This study is also discussed in ‘Release captive bred individuals’ and ‘Use holding pens at release sites’.

    Study and other actions tested
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

Bird Conservation

This Action forms part of the Action Synopsis:

Bird Conservation
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What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

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