Ardea
Official journal of the Netherlands Ornithologists' Union

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Hudson R. (1968) The white-phase Giant Petrels of the South Orkney Islands. ARDEA 56 (1-2): 178-183
The bird-ringing data of the British Antarctic Survey has been used to assess the proportion of white-phase birds in the South Orkney population of the Giant Petrel Macronectes giganteus, and whether these migrate north as juveniles as do the dominant dark-phase birds. The conclusions are: (1) The proportion of white-phase chicks reared on Signy Island is 9.1 0.8% (mean and standard deviation). (2) An analysis of the recoveries shows that the majority of white juveniles do migrate north; it seems possible however that some (perhaps one-quarter) remain within the Antarctic, but the data on which this suggestion is based is statistically significant only at the 10% level. (3) The geographical distribution of recoveries in low latitudes does not vary significantly between the two morphs.


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