Gyps vultures with Pitot airspeed at Rocamadour (data from Williams et al. 2018)

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Date
2018-11-27
DOI
https://doi.org/10.5441/001/1.4f03k6s5/1
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Citation
Williams HJ, Shepard ELC, Duriez O. 2018. Gyps vultures with Pitot airspeed at Rocamadour (data from Williams et al. 2018). Movebank Data Repository. https://doi.org/10.5441/001/1.4f03k6s5/1
Abstract
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
aeroecology,airspeed,animal movement,animal tracking,gliding,GPS logger,griffon vulture,Gyps fulvus,Gyps himalayensis,Himalayan vulture,movement ecology,soaring,social information,vulture
Taxa
Sensors
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URI
https://datarepository.movebank.org/handle/10255/move.689
BibTex
@misc{001/1_4f03k6s5/1,
  title = {Gyps vultures with Pitot airspeed at Rocamadour (data from Williams et al. 2018)},
  author = {Williams, HJ and Shepard, ELC and Duriez, O},
  year = {2018},
  URL = {http://dx.doi.org/10.5441/001/1.4f03k6s5/1},
  doi = {doi:10.5441/001/1.4f03k6s5/1},
  publisher = {Movebank data repository}
}
RIS
TY  - DATA
ID  - doi:10.5441/001/1.4f03k6s5/1
T1  - Gyps vultures with Pitot airspeed at Rocamadour (data from Williams et al. 2018)
AU  - Williams, Hannah J.
AU  - Shepard, Emily L.C.
AU  - Duriez, Olivier
Y1  - 2018/11/27
KW  - aeroecology
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/10.5441/001/1.4f03k6s5/1
DO  - doi:10.5441/001/1.4f03k6s5/1
ER  -
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