J28 DISCOVERY REPORTS 



repletion, now in a ravenous hurry chasing some unfortunate aduh but lately arrived with spoil from 



the open sea'. Or to quote Levick: 



Hitherto they had been merely remarkable for their spotless plumage, in contrast to their former dirty state, but now 



their shape too was greatly altered, for their meals, in place of merely satisfying their own individual wants, had now 



to provide for the offspring as well, and they were in consequence so distended with their heavy load of Euphaiisia 



that they were obhged to lean back to counterbalance the weight of their bellies that bulged before them as they 



walked. Frequently they would find to their cost that they had attempted too much, and overcome by the labour of 



their journey over the rough ground, they would be sick, depositing the whole load on the ground, and having perforce 



to return to the sea for more. 



Manifestly the quantities of krill consumed, and the local effect of this on the euphausian 

 population near a large rookery, must be enormous, the foraging parents, with two ravenous chicks to 

 rear, each having to eat for three. In the but moderately full stomach of an adult Gentoo Bagshawe 

 (1938) counted the remains of 960 E. superba^ from which it seems distinctly likely that the great 

 rookery at Cape Adare alone, with its nestlings, assuming half the aduh population are fishing and 

 the other half nursing, is taking the staggering figure of over 370 million euphausians from the plankton 



per day. 



The insatiable appetites of the Adelie chicks, and the astonishing rate at which they grow, has been 

 well described by Levick (191 5 6) who gives figures showing that in the first 12 days after hatching 

 they increase their birth-weight 14-fold, from 3 to 42 ounces. 



All this indeed is impressive enough. It does not, however, by any means cover the host of animals 

 that harry and devour these unfortunate shrimps. Among the vast flocks of petrels and other oceanic 

 birds that frequent the whaUng grounds there are a number of species which, although not exclusively 

 krill-eaters, habitually include E. superba, sometimes in very substantial quantities, in their otherwise 

 catholic diet. A Ust of such birds, compiled mainly from the comprehensive records of Murphy (1936) 

 with additional records by Pirie (1905 a), Wilson (19076), Wilton (1908), Falla (1937), Roberts (i940«) 

 and Bierman and Voous (1950) is given below. While it probably includes the chief krill-eaters there 

 may well be others, since a number of birds vaguely recorded as feeding on 'Euphausians', 'pelagic 

 shrimps' and so on, without specific reference to E. superba, have not been included. 



Diomedea exulans Linnaeus Wandering Albatross^ 



Diomedea melanophris Temminck Black-browed Albatross 



Phoebetria palpebrata (Forster) Light-mantled Sooty Albatross 



Priocella glacialoides (Smith) Silver Grey Petrel 



Thalassoica antarctica (Gmelin) Antarctic Petrel 



Pagodroma nivea (Forster) Snow Petrel^ 



Oceanites oceanicus (Kuhl) Wilson's Petrel* 



Pachyptela desolata Gmelin Antarctic Whale-bird 



Sterna vittata Gmelin Antarctic Tern 



Sterna macrura Naumann Arctic Tern 



Sterna vittata georgiae Reichenow Wreathed Tern 



Daption capensis Linnaeus Cape Pigeon* 



Halobaena caerulea Gmelin Blue Petrel 



1 A bulging, completely filled, Gentoo or Adelie stomach could well I believe hold considerably more than 960 krill, 

 Hartley (1934)' finding that in the much smaller Kittiwake gull 350 Thysanoessa inermis, which grows to about 30 mm., is 

 merely an average single meal. 



2 This species has not been seen taking fresh krill from the plankton. It is known, however (Matthews, 19296), to be 

 partial to krill vomited up by harpooned whales. It seems reasonable, therefore, to include it among the krill-eaters. 



3 Wilson states that the food of this abundant species consists almost entirely of E. superba. 



* Fisher (1954) believes this to be without question the world's most abundant bird. 



* Discovery Investigations record. 



