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Penguin head movement detected using small accelerometers: a proxy of prey encounter rate.
MedLine Citation:
PMID:  22031740     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
Determining temporal and spatial variation in feeding rates is essential for understanding the relationship between habitat features and the foraging behavior of top predators. In this study we examined the utility of head movement as a proxy of prey encounter rates in medium-sized Antarctic penguins, under the presumption that the birds should move their heads actively when they encounter and peck prey. A field study of free-ranging chinstrap and gentoo penguins was conducted at King George Island, Antarctica. Head movement was recorded using small accelerometers attached to the head, with simultaneous monitoring for prey encounter or body angle. The main prey was Antarctic krill (>99% in wet mass) for both species. Penguin head movement coincided with a slow change in body angle during dives. Active head movements were extracted using a high-pass filter (5 Hz acceleration signals) and the remaining acceleration peaks (higher than a threshold acceleration of 1.0 g) were counted. The timing of head movements coincided well with images of prey taken from the back-mounted cameras: head movement was recorded within ±2.5 s of a prey image on 89.1±16.1% (N=7 trips) of images. The number of head movements varied largely among dive bouts, suggesting large temporal variations in prey encounter rates. Our results show that head movement is an effective proxy of prey encounter, and we suggest that the method will be widely applicable for a variety of predators.
Authors:
Nobuo Kokubun; Jeong-Hoon Kim; Hyoung-Chul Shin; Yasuhiko Naito; Akinori Takahashi
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of experimental biology     Volume:  214     ISSN:  1477-9145     ISO Abbreviation:  J. Exp. Biol.     Publication Date:  2011 Nov 
Date Detail:
Created Date:  2011-10-27     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0243705     Medline TA:  J Exp Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  3760-7     Citation Subset:  IM    
Affiliation:
National Institute of Polar Research, 10-3 Midori-cho, Tachikawa, Tokyo 190-8518, Japan.
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