Individual study: Survival and dispersal of captive-reared Montagu's harrier Circus pygargus fledglings released in Deux-Savres and Baie de l'Aiguillon, Poitou-Charentes / Pays de la Loire, France
Amar A., Arroyo B.E. & Bretagnolle V. (2000) Post-fledging dependence and dispersal in hacked and wild Montagu's harriers Circus pygargus. Ibis, 142, 21-28
This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.
Artificially incubate and hand-rear raptors in captivity
A replicated controlled study in cereal fields in western France in 1995-6 (Amar et al. 2000) found that a programme to rescue Montagu’s harrier Circus pygargus eggs and chicks from nests in fields about to be harvested resulted in the release of 129 birds into the wild. The hatching success of 54 artificially incubated eggs was 62%: significantly lower than that of 322 naturally-incubated, wild eggs (hatching success not provided). However, fledging success of 33 hand-reared chicks was 64%, comparable to that of 313 wild chicks (wild fledging rates not provided). Among released birds, those that spent longer in captivity had shorter periods of dependence on the food provided and were in better condition. Captive-reared birds were re-observed more frequently following release (16-21% of 129 released birds re-observed vs. 8-9% of 181 naturally-fledged young), although the authors warn that this could be an artefact of lower dispersal in captive-reared birds. Eggs and chicks up to 15 days old were removed from at risk nests and released in groups of between one and eleven at two sites. Food (chicks and mice) was provided in excess during rearing and then at the release sites.