The White-headed Duck is a globally threatened species historically recorded from Spain in the west to China in the east. It has suffered major population declines, local extinctions and range fragmentation. Several projects have attempted to reintroduce captive-bred birds into parts of the former range in Europe, but with little success. Two captive stocks currently exist, one originating from Pakistan in 1968 and the other originating from Spain in 1982. This study compares the suitability of these captive stocks for specific reintroduction projects by using 11 microsatellite markers and mtDNA control region sequences to assess genetic differences between captive populations and wild birds from Spain and Greece. No significant population structure was found and all microsatellite alleles recorded in captive birds originating from Pakistan were also observed in the wild Spanish population. A higher diversity of alleles was observed in wild birds from Greece than from Spain, probably due to the effects of a strong bottleneck experienced in Spain in the 1970s. Compared with wild populations, both captive stocks have suffered a significant loss of diversity in microsatellites and mitochondrial DNA owing to founder effects and/or genetic drift, and therefore may not be well suited for release programmes. We recommend the development of a more diverse captive breeding programme based on birds taken from different areas of the range, in particular by supplementing the Spanish population with birds from North Africa. Our study shows the value of molecular tools in developing conservation programmes for threatened bird species and has implications for the design of recovery programmes.
