Noddies and Skimmers 



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but differing in their heavier, more labored flight, as well as in their habits, as 

 most of their life is spent on the surface of the open ocean, often at great dis- 

 tances from the land, where they secure their food of crustaceans, floating ani- 

 mals, and offal. They are, for the group, birds of medium size, with the bill longer 

 than the head and strong, the upper mandible curved gradually to the rather 

 acute tip, very long, pointed wings, and a graduated instead of forked tail, while 

 the tarsi are rather short and slender, and the toes long and united by a full web. 

 The plumage is mainly dusky throughout, becoming grayish white on the fore- 

 head, and on the basis of a slenderer bill and the greater length of the third pair 

 of tail feathers, counting from the outside, several of the forms are sometimes 

 separated under the generic name of Micranous, but the difference seems hardly 

 worthy of generic rank. 



The best-known species is the Common Noddy (A. stolidus), which is found 

 practically throughout the world in suitable intertropical or subtropical situations, 

 often breeding in colonies of vast size, and in some cases, as on the Tortugas, 

 building regular nests on low trees, while in other localities they are placed on 

 rocky cliffs. The Pacific Noddy (A. s. ridgivayi) differs in being darker and 

 much less brown than the last. It is found mainly about Cocos and Socorro 

 Islands, where Mr. Anthony found them nesting in abundance on a small rock, 

 placing the single egg on the bare rock without any attempt at nest building. 

 About the Galapagos Islands another still darker form occurs (A.s. galapagoensis), 

 which Snodgross and Heller tell us nests in holes in the face of the cliffs, making 

 a scant nest of a few twigs laid on the bottom of the cavity. With habits similar 

 to those of the common Noddy, but smaller in size and with the white of the 

 crown abruptly defined against the sooty brown of the neck and upper plumage, 

 is the White-headed Noddy (A. leucocapillus) of the southwestern Pacific, 

 ranging occasionally as far as the Bay of Bengal. 



The White Noddy (Gygis alba}, which ranges from the South Atlantic and 

 Indian oceans to Australia and the Pacific islands, is easily distinguished by 

 its snow-white plumage, black bill, and blue irides. 



The Skimmers (Subfamily Rhynchopina). The Skimmers, known also as 

 Scissors-bills, Razor-bills, or Shearwaters (not the true Shearwaters, however), 

 while quite Tern-like in many respects, differ from them, as indeed they do 

 from all other birds, by the peculiar modification of the bill, this being long, 

 laterally much compressed, and with the lower mandible no thicker than 

 a knife-blade. The lower mandible is also much longer than the upper one, 

 which is itself freely movable, the bill throughout being an obvious adaptation 

 for securing their food, which consists of small fish, shrimps, etc. They do 

 not dive for their food as do the Terns, nor do they pick it up while swimming, 

 for they rarely sit upon the water ; but they obtain it by skimming rapidly over 

 the surface with the lower mandible dipped into and cleaving the surface, thus 

 scooping it up much after the manner of whales. The thinning of the lower 

 mandible is clearly for the purpose of reducing the friction in passing through 

 the water, while the upper one is shortened and has become movable to keep it 

 out of the way. As regards their other characters, the Skimmers are birds of 



