Individual study: Success of captive rearing and re-release of Hawaiian crows Corvus hawaiiensis in Kona, Hawai'i, USA
Kuehler C., Harrity P., Lieberman A. & Kuhn M. (1995) Reintroduction of hand-reared alala Corvus hawaiiensis in Hawaii. Oryx, 29, 261-266
This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.
Release captive-bred individuals into the wild to restore or augment wild populations of songbirds
A replicated study on Hawaii, USA, in 1993-4 (Kuehler et al. 1995) found that at least ten of 12 Hawaiian crows (alala) Corvus hawaiiensis released into the wild survived for at least one month (with three bird surviving at least a year). The status of the other two birds was unknown. Eight of the released birds (including both with unknown statuses) were hand-reared from wild eggs (see ‘Artificially incubate and hand-rear birds in captivity’ for details), the remaining four were captive-bred birds. Birds were transferred to small cages at the release site when 46-63 days old and then into a larger aviary when 62-96 days old. Birds were then slowly released, with the timing dependent on their ability to fly and find food. Supplementary food was provided for several months after release and non-native predators (mongoose Herpestes auropunctatus and black rats Rattus rattus) were trapped from around the aviary whilst releases were on-going (see ‘Invasive and other problematic species’ for more studies of invasive species control).
Artificially incubate and hand-rear songbirds in captivity
A replicated study on Hawaii, USA, in 1993-4 (Kuehler et al. 1995) found that a total of 12 Hawaiian crow (alala) Corvus hawaiiensis nestlings were successfully artificially incubated and hand-reared from 17 eggs taken from wild nests. Three eggs were infertile, one failed to hatch due to ‘embryonic malpositioning’ and one of the 13 successful hatchlings died as a result of a yolk sac infection. This gave a total of 93% hatchability and 92% survival to 30 days. The release of some of these birds is discussed in ‘Release captive-bred individuals’.