THE GIANT PETREL. 99 



My object is to point out that there must be some active reason for the pre- 

 ponderance of this pure white phase within the limits of the ice. Yet it is not 

 easy to see how the facts can be brought within the range of the ordinary theories 

 of animal colouration. 



In the first place, it is fairly certain that the Giant Petrel has no need for 

 protective assimilation to its surroundings in the ice, and yet this is possibly the first 

 idea that occurs to one on learning that a white variety of a dark bird is very much 

 more abundant within the Antarctic Circle than without. But it is quickly followed 

 by a question respecting the enemies it hopes thereby to escape, and in this particular 

 case the answer disposes at once of the protective assimilation theory, because the 

 bird, whether black or white, has no enemies that are worthy of the name. In 

 the water, no doubt, it might be surprised by a Killer Whale (Orca yladiator) 

 or a Leopard Seal (Stenorhinchus leptonyx), but the position of any bird which 

 can rapidly take wing from the surface of the water and never goes below is 

 obviously not such as would require invisibility to protect it from such enemies as 

 these. 



Both beasts give ample warning of their approach by the noisy way in which 

 they breathe. They are dangerous only to such birds and beasts as live habitually 

 below the surface, where their approach is as sudden as it is silent and unannounced, and 

 where little safety is to be found in anything but superior speed and more rapid 

 powers of turning. On the ice floes the Giant Petrel, no matter what may be its 

 colour, shows by its lack of nervous apprehension that it is not as a rule concerned 

 with anything that may be there, except it be in the nature of something it can eat. 

 We may, therefore, quite safely dispose of the assimilation theory so far as the protection 

 of the bird from its enemies is concerned, and equally safely, I think, in so far as it is 

 supposed to help the bird in obtaining food. 



The Giant Petrel lives on any carrion that it is able to discover, and it can never 

 be at a loss during the Antarctic summer for a plentiful supply of dead seals and 

 penguins. I know not whether in the Macquarie and Auckland Islands and elsewhere 

 it is also mainly a carrion feeder, but I can answer for this in the Antarctic. One has 

 but to kill a seal on the shore in summer and visit the blubber refuse day by day 

 to realise how quickly such food attracts the birds who are looking for it. None but 

 the carrion feeders come to it ; one sees no Albatross, no Snow, Antarctic, or Wilson's 

 Petrel, though all must often scent it ; but the Giant Petrel and the Skuas come in 

 constantly increasing numbers. 



It is a fine sight to watch a Giant Petrel, with a stretch of wing as extensive 

 as that of an Albatross, beating up the wind in large circles along the shore in search 

 of scraps that the tide has left there. His flight is as even as the flight of a Diomedea ; 

 for long one may watch in vain to see a stroke of the wings, but without an effort he 

 now rises against the wind till almost at a standstill, and now with a wide majestic 

 sweep turns out to sea, and so once more up into the wind again. It is a labour- 



