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Over-representation of bird prey in pellets of South Polar Skuas

Over-representation of bird prey in pellets of South Polar Skuas
Over-representation of bird prey in pellets of South Polar Skuas
We report the first study to compare the contents of pellets and regurgitates of South Polar Skuas, Stercorarius maccormicki, at two breeding colonies on the Antarctic Peninsula. Samples were taken across years from identified breeding pairs at Potter Peninsula in sympatry with 30–40 breeding pairs of Brown Skuas, Stercorarius antarcticus lonnbergi, and from Cierva Point with 2 pairs of Brown Skuas. In contrast to the general consensus that penguins feature in the diet most prominently in the absence of Brown Skuas, we found a much more frequent occurrence of penguin remains in samples at Potter than Cierva, but only in pellets. At Cierva, penguin feathers were largely replaced in the pellets by a high frequency of non-food moss. The rare occurrence of penguins in regurgitates from both sites is consistent with scavenging rather than active predation. The high frequency of feathers in pellets at Potter is consistent with a gut-cleansing function similar to that performed by moss, which is abundant only at Cierva. We conclude that pellets over-represent penguins in the diet. For any species that consumes feathers, the evidence must consider the alternative possibility of a non-food function of ingesting feathers.
antarctica, dietary analysis, pellet analysis, regurgitate analysis, sympatric
0021-8375
979-983
Santos, M. Mercedes
f2432bf0-e5d1-4447-82d3-bf0078aa92c8
Juáres, Mariana A.
d0ee110e-e787-4ceb-8fc1-fbb1ea800c92
Rombolá, Emilce F.
93874ff9-f217-41f7-8600-8caed2264c72
García, Mirta L.
6be1f4ee-3f46-4461-b425-530c0e18229b
Coria, Néstor R.
c6864d95-9a48-4714-9f64-32a23fd2ee70
Doncaster, C. Patrick
0eff2f42-fa0a-4e35-b6ac-475ad3482047
Santos, M. Mercedes
f2432bf0-e5d1-4447-82d3-bf0078aa92c8
Juáres, Mariana A.
d0ee110e-e787-4ceb-8fc1-fbb1ea800c92
Rombolá, Emilce F.
93874ff9-f217-41f7-8600-8caed2264c72
García, Mirta L.
6be1f4ee-3f46-4461-b425-530c0e18229b
Coria, Néstor R.
c6864d95-9a48-4714-9f64-32a23fd2ee70
Doncaster, C. Patrick
0eff2f42-fa0a-4e35-b6ac-475ad3482047

Santos, M. Mercedes, Juáres, Mariana A., Rombolá, Emilce F., García, Mirta L., Coria, Néstor R. and Doncaster, C. Patrick (2012) Over-representation of bird prey in pellets of South Polar Skuas. Journal of Ornithology, 153 (3), 979-983. (doi:10.1007/s10336-012-0840-4).

Record type: Article

Abstract

We report the first study to compare the contents of pellets and regurgitates of South Polar Skuas, Stercorarius maccormicki, at two breeding colonies on the Antarctic Peninsula. Samples were taken across years from identified breeding pairs at Potter Peninsula in sympatry with 30–40 breeding pairs of Brown Skuas, Stercorarius antarcticus lonnbergi, and from Cierva Point with 2 pairs of Brown Skuas. In contrast to the general consensus that penguins feature in the diet most prominently in the absence of Brown Skuas, we found a much more frequent occurrence of penguin remains in samples at Potter than Cierva, but only in pellets. At Cierva, penguin feathers were largely replaced in the pellets by a high frequency of non-food moss. The rare occurrence of penguins in regurgitates from both sites is consistent with scavenging rather than active predation. The high frequency of feathers in pellets at Potter is consistent with a gut-cleansing function similar to that performed by moss, which is abundant only at Cierva. We conclude that pellets over-represent penguins in the diet. For any species that consumes feathers, the evidence must consider the alternative possibility of a non-food function of ingesting feathers.

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More information

Published date: 13 April 2012
Keywords: antarctica, dietary analysis, pellet analysis, regurgitate analysis, sympatric
Organisations: Environmental

Identifiers

Local EPrints ID: 340510
URI: http://eprints.soton.ac.uk/id/eprint/340510
ISSN: 0021-8375
PURE UUID: bb502104-dadc-41a3-b595-1c4138915510
ORCID for C. Patrick Doncaster: ORCID iD orcid.org/0000-0001-9406-0693

Catalogue record

Date deposited: 25 Jun 2012 09:06
Last modified: 15 Mar 2024 02:49

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Contributors

Author: M. Mercedes Santos
Author: Mariana A. Juáres
Author: Emilce F. Rombolá
Author: Mirta L. García
Author: Néstor R. Coria

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