Action Synopsis: Bird Conservation About Actions

Provide supplementary food for gulls, terns and skuas to increase adult survival

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

Key messages

A randomised, replicated and controlled study in the Antarctic found that female south polar skuas Catharacta maccormicki that were fed lost more weight whilst feeding two chicks than unfed birds. There was no difference for birds with single chicks, or male birds.


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 randomised, replicated and controlled trial on King George Island, Antarctic Peninsula, in the boreal summer of 2000-1 (Ritz 2006) found that female south polar skuas Catharacta maccormicki (also Stercorarius maccormicki) that were fed when raising two chicks lost significantly more weight than control (unfed) females (average loss of 7.9% of body weight for fed pairs vs. 4.6% for controls). There was no such effect in male skuas (average loss of 2.1% of body weight for 27 fed males vs. 5.5% for 27 controls) or if females raising single chicks were included in results (loss of 6.9% of body weight for 27 fed pairs vs. 4.5% for 27 controls). Supplementary food consisted of 25-100 g of fish provided to adults every other day, corresponding to approximately 20% of a chick’s daily energy needs. This study also includes the impact of feeding on chick growth and survival, see ‘Provide supplementary food to increase reproductive success’.

    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

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Bird Conservation

This Action forms part of the Action Synopsis:

Bird Conservation
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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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