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Providing evidence to improve practice

Action: Foster eggs or chicks of waders with wild non-conspecifics (cross-fostering) Bird Conservation

Key messages

Read our guidance on Key messages before continuing

  • A replicated and controlled study from the USA found that killdeer Charadrius vociferus eggs incubated and raised by spotted sandpipers Actitis macularia had similar fledging rates to parent-reared birds.
  • A replicated and controlled study from New Zealand found that cross-fostering black stilt Himantopus novasezelandiae chicks to black-winged stilt H. himantopus nests significantly increased nest success, but that cross-fostered chicks had lower success than chicks fostered to conspecifics’ nests.

 

Supporting evidence from individual studies

1 

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.

 

2 

A 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.

 

Referenced papers

Please cite as:

Williams, D.R., Child, M.F., Dicks, L.V., Ockendon, N., Pople, R.G., Showler, D.A., Walsh, J.C., zu Ermgassen, E.K.H.J. & Sutherland, W.J. (2019) Bird Conservation. Pages 141-290 in: W.J. Sutherland, L.V. Dicks, N. Ockendon, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2019. Open Book Publishers, Cambridge, UK.