Birds migrating from Europe to Africa cross the Sahara Desert twice a year. Despite their lack of specific physiological adaptations to the extreme heat and arid conditions, many Passerine species regularly stopover in the desert to rest or refuel. Previous studies have put out the hypothesis that species adapted to humid habitats (such as central European birds) are constrained in their behaviour while stopping over by the availability of water. This means that they will be able to successfully refuel only when drinking water is available. On the opposite hand, species from drier habitats (such as Mediterranean species) might be able to be more active and refuel even if surface water is not available. The working hypothesis of this study is that species differ in their rates of cutaneous water evaporation, and that their behaviour is constrained by the ability to retain water. To test this hypothesis we are measuring cutaneous water loss in several species with different adaptations to arid habitats at stopover sites in the deserts of Israel and Morocco. The prediction is that the species with highest cutaneous water loss will be more active and use the stopover site more if they have drinking water available, while species with low cutaneous water loss will not need drinking water to sustain activity. After measuring their water loss rates, birds are released to the site with a telemetry nanotag (www.motus.org) and their activity and stopover duration are monitored.
Profillinien-Board Vetmeduni Wien (PP27116135)