Leonida Fusani (Uni Wien):
Dept. Cognitive Biology, University of Vienna and Konrad Lorenz Institute of Ethology, University of Veterinary Medicine, Vienna
„Food, fat and Zugunruhe“
Mi. 3. April 2019 um 18:30 Uhr
Karl-Burian Hörsaal (HS 2),
Biologiezentrum – UZA1,
Althanstraße 14,
1090 Wien.
https://www.univie.ac.at/zoobot/
Migratory birds have unique behavioural and physiological adaptations to rapidly accumulate large amounts of energy reserves for their extended flights. These energy stores are acquired and lost cyclically during migratory periods in the alternation of migratory flights and refuelling stopovers. Food intake is thus intrinsically connected to migratory decisions, but the physiological signals that regulate these decisions are still scarcely known. In the last 15 years, our group and a number of collaborators studied how the physiological conditions of birds at a stopover site influence stopover duration, and in turn how food availability and food intake during stopover affect migratory decisions. Our aim was to discover what physiological factors link food intake and body condition to migratory behaviour. We recently focused on orexic-anorexic hormones that in mammals and domestic poultry are modulators of appetite and satiety. We asked if ghrelin, a hormone secreted by the gastrointestinal tract, plays an active role in the regulation of stopover duration. Most species of migratory passerines are diurnal but migrate at night. In captivity, the extent of migratory disposition of nocturnal migrants can be estimated from the intensity of nocturnal restlessness also called Zugunruhe. We found that the blood concentrations of ghrelin reflects the extent of subcutaneous fat reserves in wild migratory garden warblers, and administration of exogenous ghrelin influences Zugunruhe in temporarily caged birds. Thus, ghrelin appears to be one of the links that connect the nutritional conditions of the birds and their migratory behaviour, and one of the factors that control the alternation of stopovers and migratory flights.
L. Fusani