396 The Plover-like Birds 



The Jaegers (Stercorarius}, of which three species are known, have practically 

 the same habits as their larger relatives, obtaining their main subsistence by 

 compelling the Terns and smaller Gulls to disgorge their recently captured fish, 

 although they are not averse to carrion, and will even feed on berries such as 

 those of the crow-berry (Empetmm}. They nest in colonies and lay two, three, 

 or rarely four, olive or brownish, deeply spotted eggs. Often the nesting sites 

 are in the vicinity of fresh water, as one species, the Pomarine Jaeger (S. pomari- 

 nus), is more of an inland bird, feeding largely upon field mice and lemmings. 

 The Jaegers are all found in the northern portions of the Northern Hemisphere, 

 breeding mainly within the Arctic Circle, but during the remainder of the year 

 they are widely scattered over the globe. 



THE AUKS, PUFFINS, AND MURRES 



(Family Alcidce) 



As already pointed out, the members of the present group agree in all essential 

 anatomical characters with the Laridce, but are distinguished at once by the 

 complete absence of the hind toe, and a two-notched instead of a four-notched 

 sternum. They are for the most part medium-sized or small birds with a stocky, 

 somewhat compressed body and large head, mostly rather short but pointed 

 wings (the Great Auk is a notable exception), so that when on land their attitude 

 is more nearly erect than is that of Gulls and Terns. The anterior toes are 

 fully webbed and armed with sharp, claw-like nails, for these birds are expert 

 swimmers and divers, while the tail is always short though of normal composition, 

 and the bill extremely variable, as will be shown later. The sexes are alike in 

 coloration and the young are little different, but there is often considerable 

 difference between the summer and winter plumage. The members of this 

 family are without exception maritime, the major portion of their lives being 

 spent on the open ocean, often at a great distance from shore, the land being 

 visited only during the short nesting season. They are confined exclusively 

 to the northern parts of the Northern Hemisphere, where they fill in a measure 

 the place occupied by the Penguins in the opposite hemisphere, but not a single 

 species reaches into or beyond the tropics. The habits of the group are remark- 

 ably similar, as they secure their food of fish, crustaceans, and other aquatic 

 life in the open sea, and nest, often in communities of vast size, on the rocky 

 shores and precipitous cliffs of the Arctic islands and coasts. The egg is usually 

 single, though in the Guillemots there may be as many as three, and both birds 

 and eggs are of supreme importance to the natives of the far North, supplying 

 both food and clothing. 



The present family numbers about a dozen genera and some thirty species, 

 and is evidently of considerable antiquity, as several fossil forms have been found 

 in the middle and later Tertiary. It is capable of division into two not very 

 sharply defined subfamilies, the Fraterculince, which embraces the Puffins and 

 Auklets, and the Alcina, or typical Auks, Murres, and Guillemots. 



