Foster eggs or chicks of waders with wild non-conspecifics (cross-fostering)
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Overall effectiveness category Unknown effectiveness (limited evidence)
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Number of studies: 2
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Supporting evidence from individual studies
A replicated and controlled experiment on two islands in Lake Michigan, USA, in 1987-9 (Powell & Cuthbert 1993) found that killdeer Charadrius vociferus eggs incubated and raised by spotted sandpipers Actitis macularia did not have significantly different hatching or fledging rates, compared to parent-reared eggs and chicks (47% hatching success, 0.8 fledglings/pair and 48% fledging success for cross-fostered chicks, n = 16 broods vs. 54%, 0.6 fledglings/pair and 27% for parent-reared chicks, n = 24 broods). There were no significant behavioural differences between parent-reared and cross-fostered chicks and one cross-fostered chick was seen two years after fledging, when it courted and mated with wild killdeer. No parent-reared chicks were seen again but the authors note that killdeer have low site-fidelity and so may not be seen again.
Study and other actions testedA replicated and controlled study in mountain streams and rivers in South Island, New Zealand, in the austral springs of 1981-7 (Reed et al. 1993) found that fledging success of managed black stilt Himantopus novasezelandiae nests was at least ten times that reported from unmanaged nests (13-27 chicks fledging in the population each year, a 20-42% fledging rate vs. 2% reported in another study for unmanaged nests). Eggs were removed from black stilt nests and artificially incubated (see ‘Artificially incubate and hand-rear birds in captivity’), before being returned as they were hatching. If replacement in the original nest was not possible then eggs were placed in a foster nest, either another black stilt nest or a black-winged stilt H. himantopus nest. Fledging rates and recruitment to the local population were higher for chicks fostered by black stilts than cross-fostered chicks (66% of 50 chicks fostered by black stilts were resighted and five recruited locally vs. 19% of 21 cross-fostered chicks, with a single recruit). The authors note that cross-fostered chicks followed their foster parents on migration, probably leading to low recruitment.
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This Action forms part of the Action Synopsis:
Bird Conservation
Bird Conservation - Published 2013
Bird Synopsis