| Summary: | The knowledge of individual and environmental parameters affecting stopover length in shorebirds is important for the conservation and management of species and environments often seriously threatened, such as Mediterranean wetlands. The role of physical and habitat conditions in determining the length of stay is not always easy to study in the field, since many external factors (i.e.: atmospheric conditions) may influence the decision to leave a stopover site. Several recent studies on Passeriformes show that applying both field and laboratory research may help to understand factors affecting stopover length. Some of these studies demonstrated that the amount of migratory restlessness in passerines can be considered a good proxy for quantifying the willingness to depart from a refuelling site. Even if shorebirds have proved to be good models for laboratory research, the only papers regarding migratory restlessness in this group concern studies on orientation mechanisms, which are mainly aimed at showing their use of magnetic compass. The present work aims: (1) to investigate the spring migration ecology of Wood sandpipers (Tringa glareola) and Curlew sandpipers (Calidris ferruginea) at a Tyrrhenian stopover site, (2) to study the presence of migratory restlessness in shorebirds and its relation with body conditions and stopover length by using spring migrating Wood sandpiper as a model, (3) to develop a method useful to effectively study orientation in caged shorebirds and (4) to investigate the hierarchal relationships among compass references used by shorebirds by means of cue conflict experiments performed in Curlew sandpipers and Dunlins (Calidris alpina). Curlew and Wood sandpipers are quite common as staging species during spring migration, but they seem to follow two different migration strategies. Our data show that Curlew sandpipers arrive in the area in fat conditions and ready to depart Northbound, whereas Wood sandpipers are likely to land in the study site in depleted condition, probably just after ...
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