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Foraging behaviour of Razorbills Alca torda during chick-rearing at the largest colony in the Baltic Sea

Isaksson, Natalie LU ; Evans, Tom J. LU ; Olsson, Olof and Åkesson, Susanne LU (2019) In Bird Study 66(1). p.11-21
Abstract

Capsule: Foraging behaviour in the Razorbill Alca torda during breeding was similar to that found elsewhere, aside from dive shape. Aims: To investigate the foraging behaviour of Razorbills during the breeding season at the largest colony in the central Baltic Sea. Methods: A combination of global positioning system (GPS) and time-depth recorder (TDR) devices were used on Razorbills breeding on the island of Stora Karlsö, Baltic Sea, during the chick-rearing period. Results: Five GPS tracks and nine TDR logs were retrieved from 12 Razorbills, and 7399 dives were analysed. Razorbills foraged south and southwest of the colony. Maximum and mean (±sd) foraging range from the colony was 72.7 km and 13.1 ± 13.5 km, respectively. Mean dive... (More)

Capsule: Foraging behaviour in the Razorbill Alca torda during breeding was similar to that found elsewhere, aside from dive shape. Aims: To investigate the foraging behaviour of Razorbills during the breeding season at the largest colony in the central Baltic Sea. Methods: A combination of global positioning system (GPS) and time-depth recorder (TDR) devices were used on Razorbills breeding on the island of Stora Karlsö, Baltic Sea, during the chick-rearing period. Results: Five GPS tracks and nine TDR logs were retrieved from 12 Razorbills, and 7399 dives were analysed. Razorbills foraged south and southwest of the colony. Maximum and mean (±sd) foraging range from the colony was 72.7 km and 13.1 ± 13.5 km, respectively. Mean dive depth (15.3 ± 2.4 m) and duration (53.1 ± 8.5 s) were similar to those of a more southern Baltic Sea Razorbill colony. Dive depth had a bimodal distribution, with 70% of dives deeper than 10 m and 30% shallower than 10 m. There was a clear diel foraging pattern with 89% of dives occurring during daytime and a higher proportion of shallow dives at night. Unexpectedly, dives were primarily U-shaped. The Razorbills spent 31% of their overall time activity budget flying or diving. Conclusion: Aside from dive shape, foraging behaviour was consistent with that reported at other colonies of Razorbills. Inconsistency in dive shape may be due to a bimodal foraging strategy, local prey behaviour or competition with the Common Guillemot Uria aalge.

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author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Bird Study
volume
66
issue
1
pages
11 - 21
publisher
British Trust for Ornithology
external identifiers
  • scopus:85060832091
ISSN
0006-3657
DOI
10.1080/00063657.2018.1563044
language
English
LU publication?
yes
id
14fa927f-d891-4a13-bfa5-1c4c2ace229c
date added to LUP
2019-02-13 09:48:28
date last changed
2022-04-25 21:31:46
@article{14fa927f-d891-4a13-bfa5-1c4c2ace229c,
  abstract     = {{<p>Capsule: Foraging behaviour in the Razorbill Alca torda during breeding was similar to that found elsewhere, aside from dive shape. Aims: To investigate the foraging behaviour of Razorbills during the breeding season at the largest colony in the central Baltic Sea. Methods: A combination of global positioning system (GPS) and time-depth recorder (TDR) devices were used on Razorbills breeding on the island of Stora Karlsö, Baltic Sea, during the chick-rearing period. Results: Five GPS tracks and nine TDR logs were retrieved from 12 Razorbills, and 7399 dives were analysed. Razorbills foraged south and southwest of the colony. Maximum and mean (±sd) foraging range from the colony was 72.7 km and 13.1 ± 13.5 km, respectively. Mean dive depth (15.3 ± 2.4 m) and duration (53.1 ± 8.5 s) were similar to those of a more southern Baltic Sea Razorbill colony. Dive depth had a bimodal distribution, with 70% of dives deeper than 10 m and 30% shallower than 10 m. There was a clear diel foraging pattern with 89% of dives occurring during daytime and a higher proportion of shallow dives at night. Unexpectedly, dives were primarily U-shaped. The Razorbills spent 31% of their overall time activity budget flying or diving. Conclusion: Aside from dive shape, foraging behaviour was consistent with that reported at other colonies of Razorbills. Inconsistency in dive shape may be due to a bimodal foraging strategy, local prey behaviour or competition with the Common Guillemot Uria aalge.</p>}},
  author       = {{Isaksson, Natalie and Evans, Tom J. and Olsson, Olof and Åkesson, Susanne}},
  issn         = {{0006-3657}},
  language     = {{eng}},
  month        = {{01}},
  number       = {{1}},
  pages        = {{11--21}},
  publisher    = {{British Trust for Ornithology}},
  series       = {{Bird Study}},
  title        = {{Foraging behaviour of Razorbills Alca torda during chick-rearing at the largest colony in the Baltic Sea}},
  url          = {{http://dx.doi.org/10.1080/00063657.2018.1563044}},
  doi          = {{10.1080/00063657.2018.1563044}},
  volume       = {{66}},
  year         = {{2019}},
}