Study

Actions

This study is summarised as evidence for the following.

Action Category

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

Action Link
Bird Conservation

Clip birds’ wings on release

Action Link
Bird Conservation

Release birds as adults or sub-adults, not juveniles

Action Link
Bird Conservation
  1. Release captive-bred individuals into the wild to restore or augment wild populations of wildfowl

    A 1997 review of the Hawaiian goose (nene) Branta sandvicensis reintroduction programme (Black et al. 1997) concluded that the release of 2,150 captive-bred birds on Hawaii and Maui, USA, starting in 1949 had not resulted in a self-sustaining wild population. Estimated mortality rates ranged from 0-87% annually, although were generally low until droughts in 1973-86, when 1,200 released geese died. Mortality rates were lower in the lowest-altitude release site (at <1,300 m a.s.l.), with only three years between 1976 and 1983 having mortality rates over 15%. By contrast, the few geese released in uplands that survived the droughts did so by migrating away from their release site. Over the study period there were 515 nests recorded, with 37% raising at least one gosling. Overall there were 473 goslings raised (0.92 goslings/nest), with the highest rates in lowland sites. Birds were all released into temporary enclosure, with differences in release techniques discussed in ‘Clip birds’ wings on release’ and ‘Release birds as adults or sub-adults, not juveniles’.

     

  2. Clip birds’ wings on release

    A 1997 review of the Hawaiian goose (nene) Branta sandvicensis reintroduction programme (Black et al. 1997) concluded that birds released into temporary exclosures with their wings clipped survived less well than those released into the wild before fledging. This study is discussed in more detail in ‘Release captive-bred individuals into the wild to restore or augment wild populations’.

     

  3. Release birds as adults or sub-adults, not juveniles

    A 1997 review of the Hawaiian goose (nene) Branta sandvicensis reintroduction programme (Black et al. 1997) concluded that birds released into temporary exclosures before fledging survived better than older birds released in exclosures with their wings clipped. This study is discussed in more detail in ‘Release captive-bred individuals into the wild to restore or augment wild populations’.

     

Output references

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