366 DISCOVERY REPORTS 



Probably the species only occurs when the islands are surrounded by pack-ice, or 

 when ice is in the vicinity, for in its oceanic range the bird was very rarely found to 

 stray more than about fifty miles from the edge of the ice. 



In February 193 1 several birds were seen at the ice-edge about fifty miles north of 

 Laurie Island, and in December of that year, one at the ice-edge sixty miles north of 

 Coronation Island. In November 1932 birds were observed thirty miles south of Scotia 

 Bay, the ice being then about sixty miles south of the land. The Scotia Expedition saw 

 a number of birds near Saddle Island about the end of March, and doubtless ice was 

 near the islands at that time. 



The Antarctic Petrel, then, is only a casual visitor. No breeding ground of the 

 species is known in the Weddell area, but it is highly probable that one exists, for a 

 fair number of birds are always to be seen at sea along the Weddell ice-edge. In the 

 Bellingshausen Sea it is possible that the bird breeds on Peter 1st Island. 



Pachyptila desolata banksi, Smith, Dove Prion. 



This bird was only found nesting on Signy Island, and since the kind of ground 

 required by the species for breeding is practically confined to Signy, it is probable that 

 it is the only nesting place. The Scotia Expedition did not find the bird on Laurie 

 Island. 



The nests are made in crannies among the tumbled rocks on the screes, mainly about 

 the sloping parts of the land in preference to the cliffs. In the Borge Bay district there 

 are many flat laminated boulders lying about the moss-clad slopes, and underneath 

 these many nests were found. The nature of the ground usually precluded the digging 

 of burrows, which is the habit of the birds in other localities. 



The nests are merely shallow hollows in the earth or rock debris in which they are 

 made — a few feathers may form an inadequate lining. In January the slopes on which 

 the birds were breeding were saturated with melted snow, and numbers of nests were 

 very damp. 



Between January 17 and 21 about 120 nests were examined. Of these, forty contained 

 single eggs, most of which were freshly laid. The most advanced egg was no more than 

 a week incubated. The remaining nests had not yet been laid in, and in at least half of 

 them an old and rotten egg from the previous year was found. That so many eggs 

 should fail to hatch is not surprising when one considers the lateness of the breeding 

 dates. In South Georgia the eggs are laid at least six weeks earlier, and the young do not 

 usually leave the nests until April. By that time winter conditions are prevailing in the 

 South Orkneys, and it is a matter for wonder that any chicks are able to survive. 



The Prions are not usually seen very near pack-ice and apparently do not like it. 

 It is probable that they wait until Signy Island is clear of pack before they come ashore 

 to breed, but later in the season the ice must often be a source of great inconvenience 

 to them. 



In most of the nests in which no eggs were found, both parent birds were present 

 in the daytime, but in the nests with eggs only the sitting bird was present. Prions are 



