° 1912 J Nichols, Recognition Marks in Birds. 45 



But aside from these one or two land birds, I wish to speak 

 particularly of two groups of water birds, — the Albatross-Petrel 

 group and the Shore Birds. Some years ago I spent some time 

 studying the first at sea in the southern hemisphere where many 

 species abound. The habit of life of all is similar. They fly con- 

 stantly about close to the ocean surface looking for food. Often 

 they must go some time without food, and doubtless when they do 

 find it, it is as frequently in superabundance, — perhaps a school 

 of fish, or squid, or a dead whale. Then they gather from all 

 about to the feast. They have few enemies. Obviously a strong- 

 advertising coloration would be of advantage to such birds, coupled 

 with recognition marks, as the food of the different species would 

 be somewhat different. I found that the definite color patterns 

 of the different species were most useful in separating them. The 

 black and white Cape Pigeon has a color pattern at once conspicu- 

 ous and diagnostic, differentiating it at any distance from the 

 numerous petrels of similar size and flight found in the same 

 regions. The gray-backed Slender-billed Fulmar has a light 

 patch on the wing which is conspicuous and diagnostic when the 

 bird is in flight In southern seas there are many petrels of atout 

 the size of a Cape Pigeon, dark aboAC and white below, with dark 

 under surfaces to the wings, whose plumage differs only in minor 

 details. The feeding habits of the different species are doubtless 

 alike, as they all follow a ship but rarely take a baited hook, which 

 the Cape Pigeon and Slender-billed Fulmar do greedily, and which 

 accounts for the disproportionate abundance of these two species 

 in collections. Apparently the general type of color mentioned 

 is a recognition mark shared by a number of species of similar 

 habits. That this is true is made more probable by the fact that 

 a markedly different type of plumage characterizes one or more 

 species of petrels of about the same size and appearance otherwise 

 but of quite different feeding habits which were observed at a 

 distance or near to, going about their business, often in flocks and 

 not coming about or paying attention to the ship. They had a 

 great deal of white on the under surfaces of the wings, and the 

 white of the breast running up towards the nape, marking oflF the 

 dark top of the head from the remainder of the dark upper parts. 

 Tery probably part of them at least were the Greater Shearwater, 



