Provide supplementary food to allow the rescue of a second chick

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

Effectiveness

15%
Certainty

14%
Harms

0%

Calculating overall effectiveness category

Background information and definitions

Many vultures and birds of prey lay more eggs each year than they can raise, with the final chick hatching several days after the first. This chick will always be weaker and is almost always killed by its siblings or starves to death as it cannot compete for food. It is thought that this chick acts as ‘insurance’ in case the older chicks die.

In very rare species, it may be beneficial to ‘rescue’ the younger chick, but doing so can be difficult. It is possible that providing extra food will allow the yonger chick to survive for long enough for a rescue attempt to be mounted.

Study locations

Key messages

A small controlled study in Spain found that second chicks from lammergeier Gypaetus barbatus nests survived longer if nests were provided with food, allowing one chick to be rescued.

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 controlled study in the Spanish Pyrenees in spring 2004-5 and 2008 (Margalida et al. 2009) found that second-hatched lammergeier (bearded vulture) Gypaetus barbatus chicks from two nests provided with supplementary food survived for nine days, as opposed to seven, five and four days for a partially-supplemented nest and two control (unfed) nests, respectively. In a third supplemented nest (in 2008), the second-hatched chick survived for five days and was removed to be hand-reared and incorporated into a captive-breeding programme. Supplementary food consisted of 2-3 kg of dead rabbits within 100 m of the nests every two days from the hatching of the first chick until the death (or removal) of the second chick. The partially-supplemented nest was provided with food on just one day.
Study and other actions tested
Referenced paper
Margalida A., Garca D., Heredia R. & Bertran J. (2009) Video-monitoring helps to optimize the rescue of second-hatched chicks in the endangered bearded vulture Gypaetus barbatus. Bird Conservation International, 20, 55-61.

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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Provide supplementary food for vultures to increase adult survival Action Link	Unknown effectiveness (limited evidence)	3	Synopsis Link
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