Dimorphism in Stercorarius pomarinus (Temminck)

SUMMARY. Records from the literature are collected about the proportions of dark and pale forms of the Pomatorhine Skua. The breeding range falls into two areas, one from Novaya Zemlya to north‐west Alaska, the other from the Mackenzie River to west Greenland. In both these areas dark birds are even...

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Bibliographic Details
Published in:Ibis
Main Author: Southern, H. N.
Format: Article in Journal/Newspaper
Language:English
Published: Wiley 1944
Subjects:
Arctic
Greenland
Mackenzie River
Arctic skua
Mackenzie river
Novaya Zemlya
Stercorarius pomarinus
Alaska
Online Access:http://dx.doi.org/10.1111/j.1474-919x.1944.tb07528.x
https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1474-919X.1944.tb07528.x
https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1474-919X.1944.tb07528.x
Description
Summary:SUMMARY. Records from the literature are collected about the proportions of dark and pale forms of the Pomatorhine Skua. The breeding range falls into two areas, one from Novaya Zemlya to north‐west Alaska, the other from the Mackenzie River to west Greenland. In both these areas dark birds are evenly distributed in the proportion of 1 in 5–20, though there is a slight suggestion that they. are less common in the second than in the first region. This even, distribution contrasts with tile cline in dimorph‐ratio known to exist in the Arctic Skua. Pomatorhine Skuas fluctuate in breeding strength from year to year. This is probably connected with the lemming cycle.

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