congeneric Spice Fince Lonchura punctulataeven if they were not themselves
either incubating or rearing young at the time (C.G. Jones, unpublished).
Chick rescue
Some species of birds hatch more young than they successfully rear, and in any
restoration project opportunities may arise to rescue failing chicks. Rescued
chicks are likely to be under-weight and dehydrated, with reduced survival
chances, but some survive for release to the wild.
The young of several species of eagles engage in siblicide or “cainism,” where
one chick may kill its siblings. Studies on Lesser Spotted Eagles Aquila pomarina,
Spanish Imperial Eagles and Madagascar Fish Eagles Haliaeetus albicillahave all
demonstrated that the productivity of these eagles can be increased by removing
the weakest chick for hand-rearing, fostering or cross-fostering (Meyburg 1978;
Watson et al. 1996; Cade 2000). This approach has potential to boost the
productivity of rare eagles.
Rescuing chicks that are not growing well has been a valuable technique in the
management of the California Condor (Snyder and Snyder 2000) and Echo
Parakeet. Wild parakeets lay clutches of 2–4 eggs but usually only rear one chick,
sometimes two, apparently because insufficient food is available. To avoid this loss,
wild parakeets are allowed to hatch their eggs and keep the young for the first
5–8 days. Young were then removed and either hand reared or given to foster pairs
that had failed to hatch their own young. Of 38 chicks rescued when starving, 29
(78%) fledged, while of 14 chicks removed earlier, all subsequently fledged.
Supportive care of young birds in the nest
Providing supportive care to young birds in the nest during periods of temporary
food shortage, when the adults are having difficulty feeding them, may improve
their survival chances. Young birds fostered under inexperienced adults, in
replacement of a clutch of eggs, may need some hand-feeding while the parents
learn how to feed them adequately. During inclement weather, when adults have
difficulty foraging, it has sometimes proven necessary to feed and re-hydrate
young Mauritius Kestrels and Echo Parakeets in the nest to help them through a
brief period of food shortage. However, it is usually more efficient to feed the
adults, if they will accept supplemental food, and let them pass it on to the young.
12.5 Reintroduction and translocations
12.5.1Reintroduction
Reintroduction is usually defined as the release of captive-bred or captive-reared
birds into an area which was once part of their range but from which they have
288 |Conservation management of endangered birds