96 EDWARD A. WILSON. 



of danger than we expected, and it was only with considerable difficulty that 

 we could get close enough to shoot them as they ran with outspread wings and long 

 strides to rise and go out to sea. We obtained three of the white birds and also one of 

 the darkest brown. It was not easy to kill them on the shore, as they were all at the 

 water's edge and took wing to the drifting ice floes, where they were soon completely 

 out of reach. The white birds had the usual few dark feathers scattered here and 

 there, but otherwise were wholly white. None of them, so far as we could ascertain, 

 were nesting on this peninsula, nor did the ' Southern Cross ' Expedition, in their stay 

 upon the spot, see any Giant Petrels nesting. It is a curious fact, too, that a white 

 Giant Petrel was, during their stay in 1900, considered a very great rarity by the 

 members of the ' Southern Cross,' though they were stationed here for some thirteen 

 months, covering part at least of two summer seasons. In connection with the 

 frequency of the white phase of the Giant Petrel within the Antarctic Circle, as 

 compared with its infrequency in the more temperate part of the Southern Oceans, I have 

 put in a tabular form an estimate of the various phases, necessarily a very rough one, 

 but formed by daily observation during the whole of our stay within the Antarctic Circle. 



It is, of course, impossible, in a cruise on board ship, to say accurately what 

 number of any particular species of bird has been seen each day, but it is possible to 

 discriminate between such numbers as two, or half a dozen, or a score or more, and 

 it is such a rough-and-ready estimate as this that I have attempted to make. It 

 shows that whereas the white phase is a rarity in the sub-Antarctic region, it is by 

 no means so rare in the region of the ice. In the sub-Antarctic region, moreover, 

 Ostdfrac/a is almost always of a uniform colour, either uniformly dark, blackish brown, 

 or blackish grey, when viewed on the wing at a short distance, or else uniformly white. 

 But within the circle one sees not only these unicolour phases, but a very considerable 

 number of birds which vary between the white and dark. Some birds are dark all 

 over, with white head and neck, and some are mottled grey, brown, and white. 



It will be seen from this analysis, then, that in a voyage of 140 days, covering 

 many thousands of miles of the sub-Antarctic ocean, only one White Giant Petrel was 

 seen among several hundreds of the uniformly darker ones, giving a very small 

 percentage, and also that the percentage of intermediate forms is almost as small, 

 amounting to three or four in all, or less than a half per cent. Whereas if we compare 

 this with the proportion of White to Dark and Intermediate birds in latitudes where 

 ice conditions are persistent, we see that in a total of about a hundred birds observed 

 during half as many days, in a voyage covering only about 4,000 miles, the percentage 

 of intermediate birds rises to 23-J per cent., and of white to as much as 30 per cent. 

 Thus : Between 33 S. and G6 7' S., we observed :- 



Dark birds. Intermediate. White. 



At least 500. J. 1. 



Whereas, between 66 7' S. and 78 S. we observed : 



Dark birds. Intermediate. White. 



About 60. 14. 18. 



