Action Synopsis: Bird Conservation About Actions

Release captive-bred individuals into the wild to restore or augment wild populations of bustards

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

Study locations

Key messages

  • Three reviews of a release programme for houbara bustard Chlamydotis undulata macqueenii in Saudi Arabia and a replicated trial as part of the same programme found low initial survival of released birds, but the establishment of a breeding population and an overall success rate of 41%.
  • The programme tested many different release techniques, discussed elsewhere, with releases being most successful if sub-adults were released, able to fly, into a large exclosure.


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 review of a captive breeding programme in southwest Saudi Arabia (Seddon et al. 1995) reported that, of six houbara bustards Chlamydotis undulata macqueenii released in three separate trials in 1991-2, only two survived, of which one was recaptured. This programme is discussed in more detail in ‘Use captive breeding to increase or maintain populations’, ‘Use artificial insemination in captive breeding’ and ‘Artificially incubate and hand-rear birds in captivity’.

    Study and other actions tested
  2. A review (Jaime et al. 1996) of the same release programme as in Seddon et al. 1995 found that houbara bustard Chlamydotis undulata macqueenii releases were most successful when sub-adult birds were released into a large (4 km2) fenced enclosure, compared with releases of birds without an enclosure, releases of chicks or releases of sub-adult birds with clipped wings. Four adults and sub-adults were released without an enclosure in 1991 and all were killed within three days by foxes. This study is also discussed in ‘Use captive breeding to increase or maintain populations’ and ‘Use artificial insemination in captive breeding’. The other release techniques are discussed in ‘Release birds in ‘coveys’, ‘Use holding pens at site of release’ and ‘Use holding pens at site of release and clip birds’ wings’.

    Study and other actions tested
  3. A review (Gelinaud et al. 1997) of the same release programme as in Seddon et al.1995 reports a houbara bustard Chlamydotis undulata macqueenii population established in southwest Saudi Arabia through releases of captive-bred birds in 1993-4 (discussed in Combreau & Smith 1998), bred for the first time in 1995. Of 22 females and 13 males in the population, three females and one male were confirmed as breeding. One yearling female raised three chicks to fledging (at 38-42 days old) whilst two other females laid a total of three eggs, all of which were infertile. The authors suggest that infertility may be caused by a low density of males and inexperienced females. One infertile brood was replaced with fertile eggs, discussed in ‘Foster eggs or chicks with wild conspecifics’.

    Study and other actions tested
  4. A replicated trial (Combreau & Smith 1998) as part of the same release programme as in Seddon et al. 1995 and Gelinaud et al. 1997 found that 35 of 85 houbara bustards Chlamydotis undulata macqueenii (41%) released at a desert steppe site in southwest Saudi Arabia were successfully introduced. This study investigates how different release techniques affected survival, discussed in ‘Release birds as sub-adults or adults, not juveniles’ and ‘Use holding pens at release sites’. The effect of predator removal is discussed in ‘Control predators not on islands’.

    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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