24 EDWARD A. WILSON. 



chick is a special development for its protection while lying on the snow-covered sea- 

 ice which forms its earliest nursery, but this explanation is by no means borne out by 

 facts. From September to December the chick exists on the floes of the sea-ice upon 

 which it was hatched without ever entering the water. Its enemies, therefore, in the 

 Antarctic can only be other birds. There are no seals that would disturb these chicks 

 on the ice, and the only birds that might interfere with them are the Skua (Megalestris 

 maccormicki) and the Giant Petrel ( Ossifraga gigantea). Both, however, are migrants 

 and neither would appear on the Emperor Penguin's breeding ground until the end of 

 October, some two months after the chickens have left their eggs, and when they would 

 already have reached the size of a full-grown Skua. 



I do not believe that the Skua is responsible for the death of any of the Emperors' 

 young, neither do I believe that the white down is the result of a need for protection 

 from any enemies that we know as yet. 



The Giant Petrel might occasionally attack the young of the Emperor Penguin, 

 but as far as our own and all other observations go, they lead one to look upon the 

 Giant Petrel as a carrion-feeder with little tendency to attack living animals. It must 

 also be remembered that, like the Skua, the Giant Petrel is 'far to the north at the 

 outskirts of the pack ice in September and October when the Emperor chicks are in 

 their most helpless state, and that they come southward only with the southward migra- 

 tion of the Adelie Penguins in October. 



It may be said that the Sea Leopard (Stenorhinchus leptonyx) is a danger to the 

 Emperor Penguin's young, and this seal certainly feeds on full-grown Emperors, but these 

 must be attacked and caught in the water, where the Sea Leopard is probably one of the 

 fastest animals of the south. There is little reason to think that he would attempt to 

 catch such an active animal as the Emperor chicken on an icefloe, where his own pace is 

 slow and his movements clumsy, and where he may be seen sunning himself in friendly 

 neighbourhood with other seals and penguins, none of which fear him on the ice.* 



It is obvious, therefore, that the white colouration of the Emperor chick has in 

 this case nothing whatever to do with the theory of protective assimilation. The 

 young bird while in the down is careful never to leave the ice, and there can be no 

 reason to think that it requires any protection other than its parents can give it until 

 it sheds the white down and takes on the dark grey plumage of the first year's bird. 

 This makes it still more difficult to supply a reason for its colouration. As a matter 

 of fact, anything more conspicuous than a jet-black head, such as it has, on a field of 

 smooth sea-ice could hardly be imagined ; but the ice of the pack is seldom smooth, and 

 in a broken mass of disintegrating floes where every piece has others forced upon it, 

 and the movement and wash of the sea has worn them into strange fantastic shapes 

 with holes and hollows, it is easy to see that a white bird would be very inconspicuous 

 indeed, and the more so if its whiteness is helped out by the addition of a black head 



* Dr. Pirie states, however, that the Sea Leopard has been seen to come up alongside a floe on which 

 penguins were resting, seize one in its jaws, and sweep down again with its prey, Voy. ' Scotia,' p. 222. 



