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Nocturnal migratory songbirds adjust their travelling direction aloft: evidence from a radiotelemetry and radar study.

Sjöberg, Sissel LU and Nilsson, Cecilia LU (2015) In Biology Letters 11(6).
Abstract
In order to fully understand the orientation behaviour of migrating birds, it is important to understand when birds set their travel direction. Departure directions of migratory passerines leaving stopover sites are often assumed to reflect the birds' intended travel directions, but this assumption has not been critically tested. We used data from an automated radiotelemetry system and a tracking radar at Falsterbo peninsula, Sweden, to compare the initial orientation of departing songbirds (recorded by radiotelemetry) with the orientation of songbird migrants in climbing and level flight (recorded by radar). We found that the track directions of birds at high altitudes and in level flight were more concentrated than the directions of... (More)
In order to fully understand the orientation behaviour of migrating birds, it is important to understand when birds set their travel direction. Departure directions of migratory passerines leaving stopover sites are often assumed to reflect the birds' intended travel directions, but this assumption has not been critically tested. We used data from an automated radiotelemetry system and a tracking radar at Falsterbo peninsula, Sweden, to compare the initial orientation of departing songbirds (recorded by radiotelemetry) with the orientation of songbird migrants in climbing and level flight (recorded by radar). We found that the track directions of birds at high altitudes and in level flight were more concentrated than the directions of departing birds and birds in climbing flight, which indicates that the birds adjust their travelling direction once aloft. This was further supported by a wide scatter of vanishing bearings in a subsample of radio-tracked birds that later passed an offshore radio receiver station 50 km southeast of Falsterbo. Track directions seemed to be more affected by winds in climbing compared with level flights, which may be explained by birds not starting to partially compensate for wind drift until they have reached cruising altitudes. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biology Letters
volume
11
issue
6
publisher
Royal Society
external identifiers
  • pmid:26085501
  • wos:000357685300023
  • scopus:84946593534
ISSN
1744-9561
DOI
10.1098/rsbl.2015.0337
project
CAnMove
language
English
LU publication?
yes
id
9ec60e97-b735-4977-9f0c-b61457cb15b8 (old id 7485036)
date added to LUP
2015-08-13 09:38:08
date last changed
2017-05-21 03:20:08
@article{9ec60e97-b735-4977-9f0c-b61457cb15b8,
  abstract     = {In order to fully understand the orientation behaviour of migrating birds, it is important to understand when birds set their travel direction. Departure directions of migratory passerines leaving stopover sites are often assumed to reflect the birds' intended travel directions, but this assumption has not been critically tested. We used data from an automated radiotelemetry system and a tracking radar at Falsterbo peninsula, Sweden, to compare the initial orientation of departing songbirds (recorded by radiotelemetry) with the orientation of songbird migrants in climbing and level flight (recorded by radar). We found that the track directions of birds at high altitudes and in level flight were more concentrated than the directions of departing birds and birds in climbing flight, which indicates that the birds adjust their travelling direction once aloft. This was further supported by a wide scatter of vanishing bearings in a subsample of radio-tracked birds that later passed an offshore radio receiver station 50 km southeast of Falsterbo. Track directions seemed to be more affected by winds in climbing compared with level flights, which may be explained by birds not starting to partially compensate for wind drift until they have reached cruising altitudes.},
  articleno    = {20150337},
  author       = {Sjöberg, Sissel and Nilsson, Cecilia},
  issn         = {1744-9561},
  language     = {eng},
  number       = {6},
  publisher    = {Royal Society},
  series       = {Biology Letters},
  title        = {Nocturnal migratory songbirds adjust their travelling direction aloft: evidence from a radiotelemetry and radar study.},
  url          = {http://dx.doi.org/10.1098/rsbl.2015.0337},
  volume       = {11},
  year         = {2015},
}