jjo DISCOVERY REPORTS 



large carrion-eater sometimes takes its krill directly from the sea, Wilton (1908) recording that the 



stomach contents of a speciman shot on the pack hundreds of miles from land 'consisted mostly of 



Euphausia '. 



The Brown Skua of South Georgia, Catharacta skua lonnbergi (Mathews), is also, it seems, a 

 cathoUc feeder, much prone to carrion, that comes by its krill third-hand, Stonehouse (1956) recording 

 that during the nesting season it commonly attacks Gentoo chicks, tearing them open, removing the 

 viscera and crop contents and regurgitating them for the benefit of its young. ' On more than one 

 occasion, ' he continues, 'a bird was seen to take off from its roost, circle high over its territory, and 

 fly off out of sight along the coast, returning one or two hours later to deposit a cropful of krill (no 



doubt removed from the crop of a Gentoo chick) at the feet of its chick The possibility that the 



krill was collected directly from the sea^ cannot altogether be excluded, but it seems extremely unlikely 

 in view of the general nature and feeding habits of the birds'. 



Routh (1949) reports the occurrence of vast flocks of the Short-tailed Shearwater, Puffinus tenui- 

 rostrts (Temminck), the famous 'Mutton Bird' of the Bass Strait, which he says would spend much 

 time resting on icebergs near the patches of krill on which they fed ' in a seething mass '. There can 

 be little doubt, however, that he must have mistaken the closely allied Sooty Shearwater, Puffinus 

 griseus (Gmelin), for this species with which, as Murphy (1936) points out, at a distance it can readily 

 be confused.2 palla (1937) records P. griseus as breeding on Macquarie Island, stating that it was 

 seen in large flocks by the Australian expedition as far south as 64° S in 131° E in February 191 3, 

 while Mawson (1942), in the same month and year, refers to flocks of 'dark petrels (Mutton Birds?)' 

 in 65° S, 118° E. Dr T. J. Hart (personal communication) has also seen it in great abundance still 

 farther south near the Balleny Islands, apparently he thought feeding on the krill. Reports of 

 'Mutton Birds' in this locality by Balleny (1839), McNab (1839), Borchgrevink (1901) and Hanson 

 (1902) no doubt also refer to this species. Balleny twice records 'numerous flocks' and from all 

 accounts it would appear to be extremely plentiful in East Wind waters south of Macquarie Island 

 throughout the southern summer. So far, however, it has not been reported, except in negligible 

 numbers, far south in the Pacific sector (Holgersen, 1957). 



From an examination of ninety-five stomachs, representing fifteen species, Bierman and Voous 

 (1950) conclude that the 'Opossum-shrimp {Euphausia spec.) is the basic diet of all Antarctic sea- 

 birds', adding that cephalopods come next in importance^ and that fish and pteropods are seldom 

 eaten. Put in this way the Opossum-shrimp could, of course, refer to Antarctic euphausians in 

 general. However, since the authors refer to it unequivocally as E. superba earlier in this paper and 

 make repeated references to the presence of 'orange' or 'bright orange remains of Euphausia' in the 

 stomach contents they examined, there can be little doubt that it is to E. superba, the dominating 

 shrimp of these southern waters, that they allude. 



The ravages of fish, while possibly little less severe than the toll exacted by oceanic birds, are not 

 so easy to gauge, for few Antarctic ichthyologists seem to have bothered very much about the food of 

 the specimens they handled. Mr N. B. Marshall, however, has told me that among the collections 

 preserved in the Natural History Museum he has found a number of substantial krill-eaters. The 

 majority are well known oceanic or coastal forms, for example, Electrona antarctica (Gunther) and 



1 The italics are mine. 



2 Kuroda (i960) also calls attention to how easily these two can be confused except at very short range. 



3 Perhaps the largest and best documented collection of southern cephalopod remains ever to be made has recently been 

 described by Dell (1959) from stomach material brought back by the B.A.N.Z. Antarctic Research Expedition. He calls 

 attention to the enormously important place cephalopods fill in the food chains of Antarctic vertebrates, especially birds, 

 and notes that although such remains can contribute little to our knowledge of the Antarctic cephalopod fauna, they do show 

 that squid are far commoner in high southern latitudes than conventional collecting gear lets us think. 



