Individual study: Effect of nestling age on the successful adoption of Montagu's harriers Circus pygargus introduced into foster nests in north-eastern Madrid province, Spain
Arroyo B.E. & Garcia J.T. (2002) Alloparental care and kleptoparasitism in the semicolonial Montagu's harrier Circus pygargus. Ibis, 144, 676-679
This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.
Foster eggs or chicks of raptors with wild conspecifics
A replicated study in cereal fields in Madrid province, central Spain, in the breeding seasons of 1991-6 (Arroyo & Garcia 2002) found that 15 Montagu's harrier Circus pygargus nestlings introduced into foster nests at the age of 15–20 days were all successfully ‘adopted’, whereas three fledglings introduced at the age of 27–29 days were rejected by their intended foster parents and attacked when they begged for food. All nests already had nestlings in and all but two received a single nestling. One of these one was given two 15-20 day-old nestlings, the other two 27-29 day-olds.