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Adaptive variation of airspeed in relation to wind, altitude and climb rate by migrating birds in the Arctic

Hedenström, Anders LU ; Alerstam, Thomas LU ; Green, Martin LU and Gudmundsson, GA (2002) In Behavioral Ecology and Sociobiology 52(4). p.308-317
Abstract
The power expenditure of flapping flight in birds is characterised by a U-shaped function of speed through the air. From this relationship and the assumption of limited power available from flight muscles, it is possible to predict changes in the birds' airspeed in relation to external factors such as wind. These predictions are derived from flight mechanical theory and optimality criteria concerning migration or transport flight economy. Using tracking radar we measured flight speeds of migrating birds at 12 sites along the Northwest Passage in arctic Canada. We analysed variation in airspeed (V-a) in relation to the wind effect (V-g-V-a, where V-g is the groundspeed), vertical speed (V-z), altitude (z) and the compensation for the amount... (More)
The power expenditure of flapping flight in birds is characterised by a U-shaped function of speed through the air. From this relationship and the assumption of limited power available from flight muscles, it is possible to predict changes in the birds' airspeed in relation to external factors such as wind. These predictions are derived from flight mechanical theory and optimality criteria concerning migration or transport flight economy. Using tracking radar we measured flight speeds of migrating birds at 12 sites along the Northwest Passage in arctic Canada. We analysed variation in airspeed (V-a) in relation to the wind effect (V-g-V-a, where V-g is the groundspeed), vertical speed (V-z), altitude (z) and the compensation for the amount of side wind (1/cosalpha, where cc is the angle between track and heading). We found significant effects on the variation in V-a for all four variables, revealed by multiple regression analysis, but the total variation explained was relatively small suggesting that other factors might be involved. The signs of the regression coefficients were as predicted, except for the effect of side wind where we found a negative relationship between V-a and 1/cosalpha, possibly because our sample included an unknown mixture of bird species. We also compiled information from the literature from studies reporting analyses of the effects of the four variables on V-a. Adjustment of V-a in relation to the wind effect seems nearly omnipresent among birds, while the effects of vertical speed and altitude have been reported surprisingly few times. An increased V-a with increasing alpha (and 1/cosalpha) has not been found yet, perhaps due to the lack of critical observation conditions. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Behavioral Ecology and Sociobiology
volume
52
issue
4
pages
308 - 317
publisher
Springer
external identifiers
  • wos:000178267400006
  • scopus:0036765042
ISSN
1432-0762
DOI
10.1007/s00265-002-0504-0
language
English
LU publication?
yes
id
2e9ebdd8-f2fd-4a76-9b82-704535d51a49 (old id 145512)
date added to LUP
2007-06-25 08:22:06
date last changed
2017-12-10 03:49:49
@article{2e9ebdd8-f2fd-4a76-9b82-704535d51a49,
  abstract     = {The power expenditure of flapping flight in birds is characterised by a U-shaped function of speed through the air. From this relationship and the assumption of limited power available from flight muscles, it is possible to predict changes in the birds' airspeed in relation to external factors such as wind. These predictions are derived from flight mechanical theory and optimality criteria concerning migration or transport flight economy. Using tracking radar we measured flight speeds of migrating birds at 12 sites along the Northwest Passage in arctic Canada. We analysed variation in airspeed (V-a) in relation to the wind effect (V-g-V-a, where V-g is the groundspeed), vertical speed (V-z), altitude (z) and the compensation for the amount of side wind (1/cosalpha, where cc is the angle between track and heading). We found significant effects on the variation in V-a for all four variables, revealed by multiple regression analysis, but the total variation explained was relatively small suggesting that other factors might be involved. The signs of the regression coefficients were as predicted, except for the effect of side wind where we found a negative relationship between V-a and 1/cosalpha, possibly because our sample included an unknown mixture of bird species. We also compiled information from the literature from studies reporting analyses of the effects of the four variables on V-a. Adjustment of V-a in relation to the wind effect seems nearly omnipresent among birds, while the effects of vertical speed and altitude have been reported surprisingly few times. An increased V-a with increasing alpha (and 1/cosalpha) has not been found yet, perhaps due to the lack of critical observation conditions.},
  author       = {Hedenström, Anders and Alerstam, Thomas and Green, Martin and Gudmundsson, GA},
  issn         = {1432-0762},
  language     = {eng},
  number       = {4},
  pages        = {308--317},
  publisher    = {Springer},
  series       = {Behavioral Ecology and Sociobiology},
  title        = {Adaptive variation of airspeed in relation to wind, altitude and climb rate by migrating birds in the Arctic},
  url          = {http://dx.doi.org/10.1007/s00265-002-0504-0},
  volume       = {52},
  year         = {2002},
}