Roosting behaviour of Stone-curlews Burhinus oedicnemus wintering in central Italy

We have monitored winter roosts of Stone-curlew Burhinus oedicnemus in Grosseto Province, Tuscany, in central Italy since 1993. We show that there is a wintering population of about 80–190 birds in the study area, with marked variability from year to year. Stone-curlews begin to gather at winter roosts in October or early November, typically reaching peak occupancy in December–January and leaving around early February. We found 12 different roosts in a relatively small geographic area of about 4,500 km2; these included 11 winter roosts and one autumn pre-migratory roost, which was occupied in September–November. Most roosts are below 200 m altitude, in open farmland of different topography and with scattered or absent vegetation cover. Vocal activity and response to playback stimulation at winter roosts during daylight is almost absent, while after sunset the birds utter occasional brief spontaneous calls. Stone-curlews use some places more frequently (‘traditional roosts’, occupied for three years or more), while other sites are occupied only occasionally for one winter season. Site-fidelity (by Stone-curlews, not necessarily individual birds) is not absolute even for traditional roosts; they are often abandoned and occupied again after 5–7 years. During winter, the number of birds at each roost varies widely, suggesting a high mobility of birds among roosts. There are pairs of closely situated roosts (about 4 km apart) that appear linked by reciprocal movements of birds. We report anecdotal observations of disturbance factors, such as hunting, farmers’ work and generic human disturbance in the roosting area; we discuss these and other causes that may promote high mobility among roosts of wintering Stone-curlews.