Data from: Vultures respond to challenges of near-ground thermal soaring by varying bank angle
Data from: Vultures respond to challenges of near-ground thermal soaring by varying bank angle
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Date
2018-11-27
Citation
Williams HJ, Shepard ELC, Duriez O. 2018. Data from: Vultures respond to challenges of near-ground thermal soaring by varying bank angle. Movebank Data Repository. https://doi.org/10.5441/001/1.4f03k6s5Abstract
Many large birds rely on thermal soaring flight to travel cross-country. As such, they are under selective pressure to minimise the time spent gaining altitude in thermal updrafts. Birds should be able to maximise their climb rates by maintaining a position close to the thermal core through careful selection of bank angle and airspeed, however, there have been few direct measurements of either parameter. Here we apply a novel methodology to quantify the bank angles selected by soaring birds using on-board magnetometers. We couple these data with airspeed measurements to parameterise the soaring envelope of two species of Gyps vulture, from which it is possible to predict “optimal” bank angles. Our results show that these large birds respond to the challenges of gaining altitude in the initial phase of the climb, where thermal updrafts are weak and narrow, by adopting relatively high, and conserved, bank angles (25-35°). The angle of bank decreased with increasing altitude, in a manner that was broadly consistent with a strategy of maximising the rate of climb. However, the lift coefficients estimated in our study were lower than those predicted by theoretical models and wind-tunnel studies. Overall, our results highlight how the relevant currency for soaring performance changes within individual climbs; when thermal radius is limiting, birds vary bank angle and maintain a constant airspeed, but speed increases later in the climb in order to respond to decreasing air density.
Keywords
Gyps fulvus,Gyps himalayensis,airspeed,animal movement,animal tracking,gliding,GPS logger,griffon vulture,Gyps fulvus,Gyps himalayensis,Himalayan vulture,movement ecology,soaring,social information,vulture
DOIs of related Publications
BibTex
@misc{001/1_4f03k6s5,
title = {Data from: Vultures respond to challenges of near-ground thermal soaring by varying bank angle},
author = {Williams, HJ and Shepard, ELC and Duriez, O},
year = {2018},
URL = {http://dx.doi.org/10.5441/001/1.4f03k6s5},
doi = {doi:10.5441/001/1.4f03k6s5},
publisher = {Movebank data repository}
}RIS
TY - DATA ID - doi:10.5441/001/1.4f03k6s5 T1 - Data from: Vultures respond to challenges of near-ground thermal soaring by varying bank angle AU - Williams, Hannah J. AU - Shepard, Emily L.C. AU - Duriez, Olivier Y1 - 2018/11/27 KW - Gyps fulvus KW - aeroecology KW - Gyps himalayensis KW - airspeed KW - animal movement KW - animal tracking KW - gliding KW - GPS logger KW - griffon vulture KW - Gyps fulvus KW - Gyps himalayensis KW - Himalayan vulture KW - movement ecology KW - soaring KW - social information KW - vulture KW - Gyps fulvus KW - Gyps himalayensis PB - Movebank data repository UR - http://dx.doi.org/10.5441/001/1.4f03k6s5 DO - doi:10.5441/001/1.4f03k6s5 ER -