Menu

Javascript is not activated in your browser. This website needs javascript activated to work properly.
You are here

Towards a conceptual framework for explaining variation in nocturnal departure time of songbird migrants

Author:
  • Florian Müller
  • Philip D. Taylor
  • Sissel Sjöberg
  • Rachel Muheim
  • Arseny Tsvey
  • Stuart A. Mackenzie
  • Heiko Schmaljohann
Publishing year: 2016-10-17
Language: English
Publication/Series: Movement Ecology
Volume: 4
Issue: 1
Document type: Journal article
Publisher: BioMed Central

Abstract english

Most songbird migrants travel between their breeding areas and wintering grounds by a series of nocturnal flights. The exact nocturnal departure time for these flights varies considerably between individuals even of the same species. Although the basic circannual and circadian rhythms of songbirds, their adaptation to migration, and the factors influencing the birds' day-to-day departure decision are reasonably well studied, we do not understand how birds time their departures within the night. These decisions are crucial, because the nocturnal departure time defines the potential flight duration of the migratory night. The distances covered during the nocturnal migratory flights in the course of migration in turn directly affect the overall speed of migration. To understand the factors influencing the arrival of the birds in the breeding/wintering areas, we need to investigate the mechanisms that control nocturnal departure time. Here, we provide the first conceptual framework for explaining the variation commonly observed in this migratory trait. The basic schedule of nocturnal departure is likely regulated by both the circannual and circadian rhythms of the innate migration program. We postulate that the endogenously controlled schedule of nocturnal departures is modified by intrinsic and extrinsic factors. So far there is only correlative evidence that birds with a high fuel load or a considerable increase in fuel load and significant wind (flow) assistance towards their migratory goal depart early within the night. In contrast, birds migrating with little fuel and under unfavorable wind conditions show high variation in their nocturnal departure time. The latter may contain an unknown proportion of nocturnal movements not directly related to migratory flights. Excluding such movements is crucial to clearly identify the main drivers of the variation in nocturnal departure time. In general we assume that the observed variation in the nocturnal departure time is explained by individually different reactions norms of the innate migration program to both intrinsic and extrinsic factors.

Keywords

  • Evolutionary Biology
  • Ecology
  • Circannual and circadian rhythms
  • Departure
  • Innate migration program
  • Migration
  • Night
  • Songbird
  • Time

Other

Published
  • Lund Vision Group
  • ISSN: 2051-3933
Rachel Muheim
E-mail: rachel.muheim [at] biol.lu.se

Researcher

Functional zoology

+46 46 222 31 93

B-B314

4

Centre for Animal Movement Research
Evolutionary Ecology, Department of Biology
Ecology building S-223 62 Lund Sweden