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Flight speeds of swifts (Apus apus): seasonal differences smaller than expected.

Henningsson, Per LU ; Karlsson, Håkan LU ; Bäckman, Johan LU ; Alerstam, Thomas LU and Hedenström, Anders LU (2009) In Royal Society of London. Proceedings B. Biological Sciences 276. p.2395-2401
Abstract
We have studied the nocturnal flight behaviour of the common swift (Apus apus L.), by the use of a tracking radar. Birds were tracked from Lund University in southern Sweden during spring migration, summer roosting flights and autumn migration. Flight speeds were compared with predictions from flight mechanical and optimal migration theories. During spring, flight speeds were predicted to be higher than during both summer and autumn due to time restriction. In such cases, birds fly at a flight speed that maximizes the overall speed of migration. For summer roosting flights, speeds were predicted to be lower than during both spring and autumn since the predicted flight speed is the minimum power speed that involves the lowest energy... (More)
We have studied the nocturnal flight behaviour of the common swift (Apus apus L.), by the use of a tracking radar. Birds were tracked from Lund University in southern Sweden during spring migration, summer roosting flights and autumn migration. Flight speeds were compared with predictions from flight mechanical and optimal migration theories. During spring, flight speeds were predicted to be higher than during both summer and autumn due to time restriction. In such cases, birds fly at a flight speed that maximizes the overall speed of migration. For summer roosting flights, speeds were predicted to be lower than during both spring and autumn since the predicted flight speed is the minimum power speed that involves the lowest energy consumption per unit time. During autumn, we expected flight speeds to be higher than during summer but lower than during spring since the expected flight speed is the maximum range speed, which involves the lowest energy consumption per unit distance. Flight speeds during spring were indeed higher than during both summer and autumn, which indicates time-selected spring migration. Speeds during autumn migration were very similar to those recorded during summer roosting flights. The general result shows that swifts change their flight speed between different flight behaviours to a smaller extent than expected. Furthermore, the difference between flight speeds during migration and roosting among swifts was found to be less pronounced than previously recorded. (Less)
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author
organization
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Contribution to journal
publication status
published
subject
in
Royal Society of London. Proceedings B. Biological Sciences
volume
276
pages
2395 - 2401
publisher
Royal Society
external identifiers
  • wos:000266990700009
  • scopus:66749147344
ISSN
1471-2954
DOI
10.1098/rspb.2009.0195
language
English
LU publication?
yes
id
b67bad2f-1f86-472e-8412-ca9b471c9b3b (old id 1367438)
date added to LUP
2009-04-07 08:13:39
date last changed
2017-11-12 03:36:45
@article{b67bad2f-1f86-472e-8412-ca9b471c9b3b,
  abstract     = {We have studied the nocturnal flight behaviour of the common swift (Apus apus L.), by the use of a tracking radar. Birds were tracked from Lund University in southern Sweden during spring migration, summer roosting flights and autumn migration. Flight speeds were compared with predictions from flight mechanical and optimal migration theories. During spring, flight speeds were predicted to be higher than during both summer and autumn due to time restriction. In such cases, birds fly at a flight speed that maximizes the overall speed of migration. For summer roosting flights, speeds were predicted to be lower than during both spring and autumn since the predicted flight speed is the minimum power speed that involves the lowest energy consumption per unit time. During autumn, we expected flight speeds to be higher than during summer but lower than during spring since the expected flight speed is the maximum range speed, which involves the lowest energy consumption per unit distance. Flight speeds during spring were indeed higher than during both summer and autumn, which indicates time-selected spring migration. Speeds during autumn migration were very similar to those recorded during summer roosting flights. The general result shows that swifts change their flight speed between different flight behaviours to a smaller extent than expected. Furthermore, the difference between flight speeds during migration and roosting among swifts was found to be less pronounced than previously recorded.},
  author       = {Henningsson, Per and Karlsson, Håkan and Bäckman, Johan and Alerstam, Thomas and Hedenström, Anders},
  issn         = {1471-2954},
  language     = {eng},
  pages        = {2395--2401},
  publisher    = {Royal Society},
  series       = {Royal Society of London. Proceedings B. Biological Sciences},
  title        = {Flight speeds of swifts (Apus apus): seasonal differences smaller than expected.},
  url          = {http://dx.doi.org/10.1098/rspb.2009.0195},
  volume       = {276},
  year         = {2009},
}