356 DISCOVERY REPORTS 



January 1933 gave a total of about 1,500,000 nests, the birds being about equal in point 

 of numbers with P. adeliae. 



Although P. adeliae are in the vast majority on Laurie Island, there are several large 

 rookeries of P. antarctica, notably on Cape Robertson and on Ailsa Craig. Saddle, 

 Weddell, and Bruce Islands give nesting sites to large numbers of the birds, and there 

 are several small rookeries on Powell and Fredriksen Islands and the adjacent rocks and 

 islets. Coronation Island, however, is the main stronghold of the species. All along the 

 coasts, wherever rocky outcrops break through the usual ice-cliffs, small colonies of the 

 birds are established, and in Sandefjord Bay and the south-west corner of Coronation 

 Island there are huge rookeries containing at least 200,000 nests. Another large rookery 

 is established on the Robertson Islands, and there are straggling colonies on the 

 Inaccessible Islands. 



The Ringed Penguin is often found to choose nesting sites in very much steeper and 

 more difficult places than is usual with any other penguin. Sometimes the rookeries are 

 even difficult of access to man, and the toil to which the birds are put in landing on the 

 steep-to shores and climbing to their nests is often enormous (Plate X, fig. 2). 



On Fredriksen Island, and in some parts of Sandefjord Bay, birds in steep places 

 were sometimes seen to lose their footing and tumble headlong for considerable dis- 

 tances down the rocks. This experience appeared to harm them not at all. From sea- 

 ward, some of the small colonies round the coasts appeared to be placed in even steeper 

 and more precarious sites than those which were visited, this being so in particular on 

 the Inaccessible Islands. 



The birds breed about three weeks later than P. adeliae, the eggs being laid as a rule 

 in the last few days of November. On January 4, 1933, the nests in the rookeries on 

 Powell and Fredriksen Islands contained eggs and newly hatched chicks in almost equal 

 numbers, none of the chicks being more than about four days old. Each nest had two 

 eggs or young, and few deserted eggs were seen. On January 9 the birds in the Sande- 

 fjord Bay rookeries had reached the same stage, and by January 1 1 almost all the eggs 

 had hatched in this locality (Plate X, fig. i). This retardation in breeding of the birds in 

 the western part of the group may be explained by the circumstance that the Sande- 

 fjord Bay rookeries are mainly more exposed and are thus more likely to be snowed 

 over than the Fredriksen and Powell Island rookeries. 



On February 15, 193 1, the rookeries at Sandefjord Bay were visited, and at this time 

 the young were almost full grown but had not begun to shed their nestling down, 

 though the first plumage was well developed beneath it. Thus they were nearly a month 

 behind the Adelie Penguins in reaching this stage. A few of the fledglings were killed, 

 and their crops contained remains of Euphausians and Amphipods. The hatching and 

 fledging dates in the South Orkneys seem to be about the same for the South Shetlands. 



In the rookeries, the Ringed Penguin is very much less tolerant of the presence of 

 sheathbills than is the Adelie Penguin. The latter seems to ignore the sheathbill unless 

 the bird actually disturbs its nest, but it was noticed that Ringed Penguins always chased 

 sheathbills away from their chicks. The two penguins are similar in point of pugnacity, 



