Polar Biology

, Volume 29, Issue 3, pp 153–159 | Cite as

Hybridisation between South polar skua (Catharacta maccormicki) and Brown skua (C. antarctica lonnbergi) in the Antarctic Peninsula region

  • Markus S. RitzEmail author
  • Steffen Hahn
  • Tim Janicke
  • Hans-Ulrich Peter
Original Paper


Hybridisation between South polar skua (C. maccormicki) and Brown skua (C. antarctica lonnbergi) in the area of the Antarctic Peninsula is known at least since the beginning of the last century but no survey has been done so far. This paper reviews information on the species composition of skua colonies of more than 10 pairs in the Antarctic Peninsula region, and the incidence of mixed pairs. Morphometrics, population size and breeding success were examined in detail at King George Island. The northward distribution of South polar skuas extended to King George Island (62°11′ S 59°00′ W), with a small outlying population on Signy Island (60°45′ S 45°36′ W), whereas Brown skuas did not breed further south than Anvers Island archipelago (64°46′ S 64°03′ W). The proportion of mixed pairs was highest at the northern end of the ∼500-km-wide hybrid zone. Body size distribution of sympatric skuas from King George Island is clearly bimodal but overlaps considerably and hybrids cannot be identified. Skua population sizes at Potter Peninsula/King George Island remained stable between 1994 and 2004. Numbers of mixed breeding pairs fluctuated more strongly than those of pure species pairs. Breeding success of Brown skuas varied the least.


Hybrid Zone Antarctic Peninsula Breeding Pair Chinstrap Penguin Mixed Pair 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



We thank all field workers, especially K. Reinhardt for providing data during the longterm study. M. Dunn, W. Fraser and M. Sander provided unpublished skua population estimates from Signy Island, Anvers Island and from Elephant Island, respectively. P. J. Pietz and an anonymous referee provided helpful comments on the manuscript. The study was supported by DFG (Pe454).


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Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Markus S. Ritz
    • 1
    Email author
  • Steffen Hahn
    • 1
  • Tim Janicke
    • 1
  • Hans-Ulrich Peter
    • 1
  1. 1.Institute of EcologyFriedrich-Schiller University JenaJenaGermany

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