Use of multiple modes of flight subsidy by a soaring terrestrial bird, the golden eagle Aquila chrysaetos, when on migration

Tremblay, J. A.; Duerr, A. E.; Katzner, T. E.; Miller, T. A.; Cooper, J. L.; Lemaitre, J.; Turk, P.; Lanzone, M. J.; Brandes, David

Use of multiple modes of flight subsidy by a soaring terrestrial bird, the golden eagle Aquila chrysaetos, when on migration

Abstract

Large birds regularly use updrafts to subsidize flight. Although most research on soaring bird flight has focused on use of thermal updrafts, there is evidence suggesting that many species are likely to use multiple modes of subsidy. We tested the degree to which a large soaring species uses multiple modes of subsidy to provide insights into the decision-making that underlies flight behaviour. We statistically classified more than 22 000 global positioning satellite-global system for mobile communications telemetry points collected at 30-s intervals to identify the type of subsidized flight used by 32 migrating golden eagles during spring in eastern North America. Eagles used subsidized flight on 87% of their journey. They spent 41.9% +/- 1.5 ((x) over bar +/- s.e.m:, range: 18-56%) of their subsidized northbound migration using thermal soaring, 45.2%+/-2.1 (12-65%) of time gliding between thermals, and 12.9%+/-2.2 (1-55%) of time using orographic updrafts. Golden eagles responded to the variable local-scale meteorological events they encountered by switching flight behaviour to take advantage of multiple modes of subsidy. Orographic soaring occurred more frequently in morning and evening, earlier in the migration season, and when crosswinds and tail winds were greatest. Switching between flight modes allowed migration for relatively longer periods each day and frequent switching behaviour has implications for a better understanding of avian flight behaviour and of the evolution of use of subsidy in flight.

Title	Use of multiple modes of flight subsidy by a soaring terrestrial bird, the golden eagle Aquila chrysaetos, when on migration
Creator	Tremblay, J. A.
	Duerr, A. E.
	Katzner, T. E.
	Miller, T. A.
	Cooper, J. L.
	Lemaitre, J.
	Turk, P.
	Lanzone, M. J.
	Brandes, David
Publisher	Journal of the Royal Society Interface
Academic Department	Civil & Environmental Engineering
Division	Engineering
Organization	Lafayette College
Date Issued	November 6, 2015
Date Available	2023-03-31
Type	Article
Language	English
Keyword	Aquila chrysaetos
	flight behaviour
	migration
	subsidized flight
	weighted-k nearest neighbour
	golden eagle
Bibliographic Citation	Katzner, T. E., et al. (2015 Nov 6) "Use of multiple modes of flight subsidy by a soaring terrestrial bird, the golden eagle Aquila chrysaetos, when on migration." Journal of the Royal Society Interface 12 (112): 20150530.
Standard Identifier	Handle 10385/rv042v597
Standard Identifier	DOI 10.1098/rsif.2015.0530
Permalink	http://hdl.handle.net/10385/rv042v597
Rights Statement	In Copyright
Rights Holders	Duerr, A. E.
	Lemaitre, J.
	Brandes, David
	Miller, T. A.
	Tremblay, J. A.
	Lanzone, M. J.
	Katzner, T. E.
	Cooper, J. L.
	Turk, P. J.