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Weather and fuel reserves determine departure and flight decisions in passerines migrating across the Baltic Sea

Sjöberg, Sissel LU ; Alerstam, Thomas LU ; Åkesson, Susanne LU ; Schulz, Axel; Weidauer, Alexander; Coppack, Timothy and Muheim, Rachel LU (2015) In Animal Behaviour 104. p.59-68
Abstract
Departure decisions of how and when to leave a stopover site may be of critical importance for the migration performance of birds. We used an automated radiotelemetry system at Falsterbo peninsula, Sweden, to study stopover behaviour and route choice in free-flying passerines departing on flights across the Baltic Sea during autumn migration. In addition, we had an offshore receiver station (FINO 2) located about 50 km southeast from Falsterbo. Of 91 birds equipped with radiotransmitters, 19 passed FINO 2. The probability that a departing migrant passed near FINO 2 was primarily affected by winds and timing of departure. Probably, the migrants were subjected to drift by westerly winds, leading to southeasterly flight paths and an enhanced... (More)
Departure decisions of how and when to leave a stopover site may be of critical importance for the migration performance of birds. We used an automated radiotelemetry system at Falsterbo peninsula, Sweden, to study stopover behaviour and route choice in free-flying passerines departing on flights across the Baltic Sea during autumn migration. In addition, we had an offshore receiver station (FINO 2) located about 50 km southeast from Falsterbo. Of 91 birds equipped with radiotransmitters, 19 passed FINO 2. The probability that a departing migrant passed near FINO 2 was primarily affected by winds and timing of departure. Probably, the migrants were subjected to drift by westerly winds, leading to southeasterly flight paths and an enhanced probability of passing FINO 2. Most birds passing the offshore station departed early in the night, which indicates that southward departures across the Baltic Sea usually take place during this time window. Wind condition was the dominant factor explaining the variation in flight duration between Falsterbo and FINO 2. After considering wind influence, we found additional effects of fat score and cloud cover. Birds with a higher fat score performed the flight faster than leaner individuals, as did birds that departed under clear skies compared to birds departing during overcast skies. These effects may reflect a difference in migratory motivation and airspeed between lean and fat birds together with difficulties in controlling orientation in overcast situations on oversea flights when celestial cues are unavailable. Thus, winds, clouds and fuel reserves were the primary factors determining departure and flight decisions in passerine migrants at Falsterbo in autumn. (C) 2015 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
autumn migration, bird migration, departure decision, flight duration, passerine, radiotelemetry, route choice, stopover
in
Animal Behaviour
volume
104
pages
59 - 68
publisher
Elsevier
external identifiers
  • wos:000354811800011
  • scopus:84926453558
ISSN
1095-8282
DOI
10.1016/j.anbehav.2015.02.015
language
English
LU publication?
yes
id
ef9c9c91-046e-4eb7-a842-e68c579c9a12 (old id 7411476)
date added to LUP
2015-06-29 08:50:02
date last changed
2017-10-22 03:08:18
@article{ef9c9c91-046e-4eb7-a842-e68c579c9a12,
  abstract     = {Departure decisions of how and when to leave a stopover site may be of critical importance for the migration performance of birds. We used an automated radiotelemetry system at Falsterbo peninsula, Sweden, to study stopover behaviour and route choice in free-flying passerines departing on flights across the Baltic Sea during autumn migration. In addition, we had an offshore receiver station (FINO 2) located about 50 km southeast from Falsterbo. Of 91 birds equipped with radiotransmitters, 19 passed FINO 2. The probability that a departing migrant passed near FINO 2 was primarily affected by winds and timing of departure. Probably, the migrants were subjected to drift by westerly winds, leading to southeasterly flight paths and an enhanced probability of passing FINO 2. Most birds passing the offshore station departed early in the night, which indicates that southward departures across the Baltic Sea usually take place during this time window. Wind condition was the dominant factor explaining the variation in flight duration between Falsterbo and FINO 2. After considering wind influence, we found additional effects of fat score and cloud cover. Birds with a higher fat score performed the flight faster than leaner individuals, as did birds that departed under clear skies compared to birds departing during overcast skies. These effects may reflect a difference in migratory motivation and airspeed between lean and fat birds together with difficulties in controlling orientation in overcast situations on oversea flights when celestial cues are unavailable. Thus, winds, clouds and fuel reserves were the primary factors determining departure and flight decisions in passerine migrants at Falsterbo in autumn. (C) 2015 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.},
  author       = {Sjöberg, Sissel and Alerstam, Thomas and Åkesson, Susanne and Schulz, Axel and Weidauer, Alexander and Coppack, Timothy and Muheim, Rachel},
  issn         = {1095-8282},
  keyword      = {autumn migration,bird migration,departure decision,flight duration,passerine,radiotelemetry,route choice,stopover},
  language     = {eng},
  pages        = {59--68},
  publisher    = {Elsevier},
  series       = {Animal Behaviour},
  title        = {Weather and fuel reserves determine departure and flight decisions in passerines migrating across the Baltic Sea},
  url          = {http://dx.doi.org/10.1016/j.anbehav.2015.02.015},
  volume       = {104},
  year         = {2015},
}