Abstract
We collected behavioral observations and recordings of adult Eurasian Stone-curlews (Burhinus oedicnemus) in central and northern Italy, and of chicks in northern Italy. Eurasian Stone-curlews are highly vocal during spring and summer, and vocalize routinely, but less frequently, during fall and winter nights. Adult Eurasian Stone-curlews have a complex and relatively wide vocal repertoire composed of at least 11 different call types and some subtypes. Two of these calls (Kurlee and Gallop) are the most used and important; the Kurlee call is uttered year-round, while Gallop is uttered usually during the breeding season with a peak in spring. Adult vocalizations are structurally diverse; call syllable duration spans from < 0.1 to > 1.1 sec and average center frequency is between 2,190 to 3,037 Hz. The highest frequency is associated with a high intensity alarm call; some adult vocalizations can be compared to the loud rhythmically repeated calls which often occur in several species of Charadrii and Scolopaci. Five call types are used in well-defined circumstances suggesting specialized functions; the remaining calls are used mostly in combination with other call types, particularly Kurlee and Gallop calls. There are preferred and typical call combinations, which cannot be explained as random choices. We identified two main call types for chicks, which are completely different from adult calls and are developed before hatching. Juveniles up to 70 days of age utter these calls without major changes. We discuss preliminary data on vocal ontogenesis, as well as correspondences and differences between our findings and the existing literature on the adult repertoire.