Birds 59 



account will however be found to include all those likely to be 

 observed, or of any special interest. They are classified under the 

 several Orders, the characters of which are cited from Sclater, 

 the language somewhat modified. 



PYGOPODES 

 Cutting edge of bill not fringed or toothed (as it is in the 

 ducks); legs placed far behind the middle of the body, so that 

 when the bird is standing its position is more or less erect; toes 

 webbed or lobed. Diving birds, the Grebes (Colymbidae) and 

 Loons (Gaviidae), the former without evident tail feathers. Our 

 common grebe is Colymbus nigricollis calif ornicus, the American 

 eared grebe. The Pied-billed Grebe or Hell-diver, Podilymbus 

 podiccps, occurs in the summer, and especially during migration. 

 The latter is known by the short, deep, strongly compressed bill, 

 which in summer is crossed by a black band. The head is with- 

 out a crest, whereas the Colymbus has a crested crown in summer 

 plumage. The loons (three species of Gavia) are rare migrants 

 or winter visitors in Colorado. 



LONGIPENNES 

 Legs near the middle of the body, anterior toes fully webbed; 

 tarsus shorter than tail. Gulls, terns, and the Parasitic Jaeger 

 or Richardson's Skua (Stercorarius parasiticus), the last a rare 

 straggler with us. Of typical gulls (Larus) we have seven Colorado 

 species, but only one, the Ring-billed Gull (Larus delawarensis of 

 Ord) is at all common. It is known by the yellow or greenish- 

 yellow bill, with a subapical black band; or, in young birds, yellow 

 on basal, black on apical half. Dwight remarks that it is an 

 inland bird in summer, going to the seacoast in winter. L. 

 calif ornicus, a closely related bird which very rarely reaches Colo- 

 rado, has a red spot on the lower mandible. Franklin's Gull 

 (Larus franklinii of Richardson)*, with red bill and in summer 

 plumage head black with a white ring around the eye, is common 

 on migration in Kansas and Utah, but rarely crosses Colorado. Two 

 species of terns regularly occur in Colorado; Forster's Tern (Sterna 

 forsteri of Nuttall) and the Black Tern (Chlidonias** nigra suri- 



* According to Dwight (1925), Franklin's gull is to be called Hydrocoloeus pipixcan. Wagler's 

 Larus pibixcan (1831) has a year's priority over Richardson's Larus franklinii. Hydrocoloeus 

 (Kaup, 18291 is separated from Larus by its slender bill and tarsus, small size, presence of a 

 hood and different wing-pattern; but it seems to be a rather weak genus. 



**Also called Hydrochelidon, but that name is of later date. 



