@article {1076496,
	title = {Foraging at the edge of the world: low-altitude, high-speed maneuvering in barn swallows},
	journal = {Phil. Trans. Roy. Soc.},
	volume = {371},
	year = {2016},
	abstract = {While prior studies of swallow manoeuvering have focused on slow-speed flight and obstacle avoidance in still air, swallows survive by foraging at high speeds in windy environments. Recent advances in field-portable, high-speed video systems, coupled with precise anemometry, permit measures of high-speed aerial performance of birds in a natural state. We undertook the present study to test: (i) the manner in which barn swallows (<em>Hirundo rustica</em>) may exploit wind dynamics and ground effect while foraging and (ii) the relative importance of flapping versus gliding for accomplishing high-speed manoeuvers. Using multi-camera videography synchronized with wind-velocity measurements, we tracked coursing manoeuvers in pursuit of prey. Wind speed averaged 1.3{\textendash}2.0 m s<sup>-1</sup> across the atmospheric boundary layer, exhibiting a shear gradient greater than expected, with instantaneous speeds of 0.02{\textendash}6.1 m s<sup>-1</sup>. While barn swallows tended to flap throughout turns, they exhibited reduced wingbeat frequency, relying on glides and partial bounds during maximal manoeuvers. Further, the birds capitalized on the near-earth wind speed gradient to gain kinetic and potential energy during both flapping and gliding turns; providing evidence that such behaviour is not limited to large, fixed-wing soaring seabirds and that exploitation of wind gradients by small aerial insectivores may be a significant aspect of their aeroecology.},
	author = {Warrick, D. R. and Hedrick, T. L. and Biewener, A. A. and Crandell, K. E. and Tobalske, B. W.}
}
