Action: Translocate wildfowl
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- Three studies of two duck translocation programmes in New Zealand and Hawaii found high post-release survival, breeding and the successful establishment of new populations.
- A replicated study in USA found that none of 391 blue-winged teal Querquedula discors stayed in the release site and that there was high mortality after release.
- A replicated, controlled study in the USA found that wing-clipping female wood ducks Aix sponsa during translocation prevented them from abandoning their ducklings.
Supporting evidence from individual studies
A replicated study of the translocation of 377 flightless young and 14 adult blue-winged teal Querquedula discors from Minnesota, USA, to Missouri during 1956-1958 (Vaught 1964) found none had remained to nest at the two release sites by the spring of 1961. Rings were recovered from 2.3% of the released birds at the end of the year of release, suggesting high first year mortality rates. Surviving individuals appeared to migrate from the translocation site once capable of flight.
A replicated, controlled study from 1970-1973 that used three different translocation methods to translocate wild wood duck Aix sponsa broods into 32 marsh areas (previously uninhabited by wood ducks) in Maine, USA (Capen et al. 1974) found that wing-clipping females was successful in preventing duckling abandonment. Two of five females moved in their original boxes successfully cared for their young, the other three abandoned them, as did females from two natural nests that were moved. In the final 25 attempts, the females were wing-clipped and moved with their broods in a release box. Twenty-two of the 25 trials were successful. A release was successful if any duckling from a brood survived to flying age. About 87 female ducklings were transplanted to new areas, of which eight were known to return to nest in the release areas. The most effective technique for releasing the females and ducklings together was a box with a hinged bottom suspended 15-20 cm above the water.
A before-and-after study on Campbell Island, New Zealand, in 2004-5 (McClelland & Gummer 2006) investigated the success of a joint translocation/reintroduction programme, which transferred 44 wild and 61 captive-bred Campbell Island teal Anas nesiotis to the island. Between 75% and 78% of birds survived and breeding occurred. This study is discussed in more detail in ‘Release captive-bred individuals’.
A before-and-after study on Midway Atoll, Hawaii, USA (Reynolds & Klavitter 2006), found that, following the reintroduction of 42 Laysan ducks (Laysan teal) Anas laysanensis in the Octobers of 2004 and 2005, 19 of the 20 birds translocated in 2004 survived their first year. Five of six 2004 females nested in their first year, producing 11 fledgling ducklings by December 2005. Flight feathers of introduced birds were clipped, supplementary feed supplied for the first three months, and individuals monitored with radio telemetry. Although extensive habitat restoration was completed prior to the introductions (including planting native species used as nesting substrates), introduced birds were also observed to use vegetation absent from their original habitat.
Another study (Reynolds et al. 2008) of the same 42 Laysan ducks (Laysan teal) Anas laysanensis, described in Reynolds & Klavitter 2006, found that post-release survival during 2004-2006 was 86% and the population grew to 104 individuals by December 2006, with 17 of 18 founding females attempting to nest. Females translocated as juvenile birds were more likely than those translocated as adults to fledge ducklings successfully, and shorter transport times were observed to lead to reduced loss of condition.
- Vaught R.W. (1964) Results of Transplanting Flightless Young Blue-Winged Teal. The Journal of Wildlife Management, 28, 208-212
- Capen D.E., Crenshaw W.J. & Coulter M.W. (1974) Establishing breeding populations of wood ducks by relocating wild broods. The Journal of Wildlife Management, 38, 253-256
- McClelland P. & Gummer H. (2006) Reintroduction of the critically endangered Campbell Island teal Anas nesiotis to Campbell Island, New Zealand. Conservation Evidence, 3, 61-63
- Reynolds M. & Klavitter J. (2006) Translocation of wild Laysan duck Anas laysanensis to establish a population at Midway Atoll National Wildlife Refuge, United States and US Pacific Possession. Conservation Evidence, 3, 6-8
- Reynolds M.H., Seavy N.E., Vekasy M.S., Klavitter J.L. & Laniawe L.P. (2008) Translocation and early post-release demography of endangered Laysan teal. Animal Conservation, 11, 160-168