Curlews breed across Europe in grassland, heathland and bog habitats, but are among the most threatened of European breeding bird species. As a result, they are the focus of a suite of conservation interventions across the continent, such as the improvement of grassland nesting habitats, and the protection of nests and chicks from predators and destruction by agricultural activities.
With headstarting, eggs are removed from the wild and reared in carefully controlled environments, thus bypassing the threats individuals encounter during vulnerable early life stages in the wild. Birds only remain in captivity for a small part of their life cycle (egg and hatchling stages) and are released once at a less vulnerable stage to provide a quick, artificial boost to the breeding productivity of a wild population.
There is growing interest in headstarting as a conservation tool for Curlew conservation, and many organisations and government agencies across Europe are either currently using or considering its use to support declining populations by boosting the number of young birds successfully fledged each year, and hopefully future recruitment to local breeding populations. This recently published review paper led by project partner BTO provides an assessment of the outcomes of Curlew headstarting projects to date, identifies major knowledge gaps, with the aim of reviewing the effectiveness of headstarting as a tool for Curlew conservation.
Eleven active projects from five countries responded to a questionnaire circulated among a network of European Curlew researchers and conservationists. Many projects started within the past five years as part of a wider suite of conservation tools aimed at supporting the recovery of local Curlew populations. While there were differences in how and where eggs were collected and how chicks were reared, mean hatching and release rates were in excess of 70%, which is far above what is achieved in most wild populations. While this review showed that headstarting can be a highly effective tool to increase Curlew survival (at both the egg and chick stages), there is more yet to be learned to really evaluate its effectiveness as a conservation tool. Critical to this will be greater post-release monitoring to fully understand the recruitment of young birds back into breeding populations. Some projects have seen birds recruiting back locally, but many have not been running long enough to fully assess these outcomes. This review highlights remaining knowledge gaps, including understanding factors influencing variations in hatch and release rates, as well as comparable methods for monitoring released birds and the estimation of survival and recruitment rates.
Read the open access paper in Wader Study here
Read the WaderTales blog about Curlew headstarting in the UK here