BIRDS OF THE SOUTH ORKNEY ISLANDS 367 



nocturnal in their habits in the vicinity of land; they were never seen outside their 

 nesting holes in the daytime, nor were they observed anywhere close to the shore at 

 sea. At dusk they returned from sea, and flitted about in the vicinity of their nests. 

 At this time the birds in the nests all commenced intermittently to give their low 

 throaty call, and a continuous murmur could be heard all about the colony, leading to 

 the discovery of many hitherto unsuspected nests. 



This species is evidently the only Prion breeding in the islands, for all the birds seen 

 belonged to it, nor were any of the other kinds recognized at sea in the vicinity. The 

 birds in the South Orkneys are in every way indistinguishable from the South Georgian 

 birds. The eggs are similar, the plumage similar, and series of measurements of birds 

 from the two localities are as follows: 



Large numbers of the birds on Signy Island fall victims to skuas. Several skuas' 

 nests were found in the vicinity of Borge Bay, and in every case the ground in the 

 vicinity of the nest was thickly strewn with the remains of Prions. The skuas 

 apparently caught them at dawn when they left their nests, or at dusk on their return 

 from sea. 



Although Prions were never seen near the islands in daytime, in the surrounding seas 

 they are usually very numerous. In February 1931 forty were seen thirty miles south 

 of Coronation Island, and twenty at a position forty miles north of the island. In 

 November at least a thousand were observed between ten and sixty miles south of 

 Scotia Bay, and in January about 1500 between twenty and a hundred miles north of 

 Laurie Island. Almost certainly these were all P. d. banksi. The islands were several 

 times approached when they were surrounded by pack-ice, and on these occasions no 

 birds at all were seen within ten miles of the ice. 



Halobaena caerulea (Gmelin), Blue Petrel. 



This species probably deserves a place among the birds of the South Orkneys on the 

 strength of a report by one of the members of the crew of the ' Discovery 11'. Ordinary 

 Seaman A. Jones reported on January 18 that he found two Blue Petrels breeding on the 

 slopes above Borge Bay. The nests were among those of Pachyptila desolata banksi, and 

 in similar sites. He was unable to capture the birds, but obtained an egg, which was 

 unfortunately broken later. It was similar in size to that of P. d. banksi, but more 

 elongate-ovate in form than is usual with the eggs of that bird. 



He described the birds as having "white-tipped tails and more black about the head 

 than Prions", and there seems little doubt that the report is authentic. Jones had 

 taken a great interest in birds at sea, and was able to identify many species. A diligent 



