© Marcel Burkhardt
Jenni-Eiermann, S. & Jenni, L. (1998)
Habitat utilization and energy storage in passerine birds during migratory stopover.
In: Adams, N. & R.H. Slotow (Eds.): Proc. 22 Int. Omithol. Congr., Durban; University of Natal
Most migrants need to interrupt their journey at intervals for refueling in order to reach their goal. During such stopovers, a series of decisions by the bird determine the schedule and the success of its journey. We review available field data on habitat selection, landing behaviour, stopover duration, temporary home range, territoriality and refueling rate in small night-migrating passerines. It is yet unclear whether birds at stopover sites explore and assess habitat quality and how important it is for migrants to familiarize with the stopover site or to establish territories. Recapture and telemetry studies indicate a small temporary home range during stopover. Night migrating passerines migrating over hospitable areas mainly land during the night. Habitats for landing at night and dawn are probably selected visually and acoustically which guides most birds in the most appropriate vegetation structure available, but may mislead some, especially under poor visibility. During nocturnal flight, migrants may also gather information on available habitats which is used during reverse migration in front of ecological barriers. Stopover duration in continental Europe is likely to be much longer than previously thought, as Shown by a new analysis of capture-mark-recapture datasets. Evidence for an initial reduction in refueling rate after landing is controversial and may depend on environmental conditions at the stopover site. Fattening by hyperphagia also entails a metabolic shift during overnight fasting to a more effective sparing of fat depots, protein and carbohydrates and to rely instead on muscular and hepatic lipid stores.