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Flight speed adjustment by three wader species in relation to winds and flock size

Hedenström, Anders LU and Åkesson, Susanne LU (2017) In Animal Behaviour 134. p.209-215
Abstract

The selection of flight speed (airspeed) in migrating birds depends on multiple internal and external factors, such as wing morphology, weight and winds. Adjustment with respect to side winds to maintain an intended track direction may include a shift in heading direction and/or an increase in airspeed. Compensation for cross-winds cannot always be achieved if visual references are lacking or may not even be beneficial if adaptive wind drift is favourable. Flock size is an additional, although often neglected, factor that could influence the airspeed of birds. Here, we show that responses to cross-winds to achieve compensation differed on a small geographical scale (a few kilometres) in migrating shorebirds, where the availability of... (More)

The selection of flight speed (airspeed) in migrating birds depends on multiple internal and external factors, such as wing morphology, weight and winds. Adjustment with respect to side winds to maintain an intended track direction may include a shift in heading direction and/or an increase in airspeed. Compensation for cross-winds cannot always be achieved if visual references are lacking or may not even be beneficial if adaptive wind drift is favourable. Flock size is an additional, although often neglected, factor that could influence the airspeed of birds. Here, we show that responses to cross-winds to achieve compensation differed on a small geographical scale (a few kilometres) in migrating shorebirds, where the availability of topographical features such as coastlines may play an important role for the birds' behaviour. We also show that airspeed was significantly influenced by flock size in three species of shorebirds, increasing with increasing flock size. This is contrary to the prediction based on the hypothesis of energy saving by flight in flock formation, but in agreement with empirical findings for migrating terns. The reason why flock size influences airspeed remains unclear, but we propose a mechanistic explanation based on the largest/heaviest individual(s) determining the speed of the flock.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
airspeed, drift, flock size, migration, optimal flight, shorebird, wind compensation
in
Animal Behaviour
volume
134
pages
7 pages
publisher
Elsevier Ltd
external identifiers
  • scopus:85034734723
  • wos:000417983100024
ISSN
0003-3472
DOI
10.1016/j.anbehav.2017.10.022
language
English
LU publication?
yes
id
4c12dacb-11e5-4b83-bc2e-641023b4fe28
date added to LUP
2017-12-07 13:50:20
date last changed
2018-01-16 13:27:04
@article{4c12dacb-11e5-4b83-bc2e-641023b4fe28,
  abstract     = {<p>The selection of flight speed (airspeed) in migrating birds depends on multiple internal and external factors, such as wing morphology, weight and winds. Adjustment with respect to side winds to maintain an intended track direction may include a shift in heading direction and/or an increase in airspeed. Compensation for cross-winds cannot always be achieved if visual references are lacking or may not even be beneficial if adaptive wind drift is favourable. Flock size is an additional, although often neglected, factor that could influence the airspeed of birds. Here, we show that responses to cross-winds to achieve compensation differed on a small geographical scale (a few kilometres) in migrating shorebirds, where the availability of topographical features such as coastlines may play an important role for the birds' behaviour. We also show that airspeed was significantly influenced by flock size in three species of shorebirds, increasing with increasing flock size. This is contrary to the prediction based on the hypothesis of energy saving by flight in flock formation, but in agreement with empirical findings for migrating terns. The reason why flock size influences airspeed remains unclear, but we propose a mechanistic explanation based on the largest/heaviest individual(s) determining the speed of the flock.</p>},
  author       = {Hedenström, Anders and Åkesson, Susanne},
  issn         = {0003-3472},
  keyword      = {airspeed,drift,flock size,migration,optimal flight,shorebird,wind compensation},
  language     = {eng},
  month        = {12},
  pages        = {209--215},
  publisher    = {Elsevier Ltd},
  series       = {Animal Behaviour},
  title        = {Flight speed adjustment by three wader species in relation to winds and flock size},
  url          = {http://dx.doi.org/10.1016/j.anbehav.2017.10.022},
  volume       = {134},
  year         = {2017},
}