Stone-Curlews Burhinus oedicnemus Wintering in Grosseto Province (Central Italy): Status, Habitat Use and Possible Threats

The Eurasian Stone-curlew Burhinus oedicnemus is a steppe bird distributed in Europe, Asia and North Africa. Although not globally threatened, it is considered a species of European conservation concern. The Grosseto province is one of the most important areas for Stone-curlews in Central Italy. Previous studies there have found that this population is largely resident and therefore suitable for assessing long term population trends. We carried out this study from December 2013 to January 2023, surveying all known winter roost sites annually. Our estimate shows that over the past ten years, the population has remained relatively stable, with no significant increasing or decreasing trend. However, both the raw survey data and the predicted values from a GAMM model, developed to estimate the global trend, reveal considerable fluctuation in the count data. For this reason, and given the elusive behaviour of the species, it is difficult to produce an accurate estimate of the minimum and maximum number of birds wintering in the Grosseto area. Nonetheless, maximum counts of 500-600 birds suggest that this may be approximately the size of the wintering Stone-curlew population. In addition, ten GPS-tagged birds were studied to outline their roosting behaviour. These data helped to explain the observed variability in the counts. Stone-curlews exhibited two contrasting behaviours: they showed remarkable fidelity to certain roosting areas that were regularly used over multiple years, but they also displayed notable mobility between different roosts, occasionally occupying new sites not previously used. Overall, the incidence of disturbance factors was low but warrants further investigation. Recent agricultural changes in Grosseto –particularly the expansion of vineyards and the decline of traditional farming– appear to be partially exploited by Stone-curlews, which frequently used vineyards as winter roosts. However, the conservation value of these habitats remains uncertain, especially given their potential negative impacts during the breeding season.