320 



LONG-WINGED SWIMMERS — LONGIPENNES. 



ftbnipt and marked contrast with the sooty V)luek of the lores and orbital region. Only the upiicr 

 half of thj head is blackish, this color forniiiig a well-defined "hood," as in the species o{ Sterun. 

 its lower edge on a line with the rictus, and including the auriculars ; the lower eyel'.d Iniing niarkiil 

 by a whitish crescent. Only one exanii)le in the very large series of American si)eciniens a]>i)roaoliis 

 the darkest-colored individual from Europe, and even in this instance the dift'erenoe is very decided. 

 lu his paper on the Steniime (P. Z. S. 1876, p. (»43), published subseiiuently to Dr. Coues's niomi- 



r* s 



k: 



Winter plumage. 



graph in "Birds of the Northwest," Mr. Ilowaitl Saunders remarks as follows concerning tlic 

 differences lietween the Amei'iciin and the European birds of this species : — 



"In almost all the adult American specimens which I have e.xamined — abmt a dozen in num- 

 ber — the black of the under parts is of a deeper and more sooty brown lint than in any Europcun 

 examples out of upwards of a hundred from various localities, the black being as dark as in 

 //. Icucopiera — an intensity of hue which our form never possesses. In two or three examples, 

 however, all females, the lightest colored American birds approach more closely to very daik 

 specimei.s from Europe ; and in tiie young and winter plumage the two forms are absolutely undis- 

 tinguishable ; so that any specific separation is out of the (piestion." 



The geographical difference in coloration as exhibited in the series before us, which in lU'o- 

 portionate numbei-s of the two forms is just the reverse of that examine<l by Mr. Saunders, is so 

 very marked that it is only in view of the possible intei'gradation through the lighter Americui 

 and the darker European examples that we consider them as specifically identical. The extreme 

 and average measurements of five adults of the European form are as fidlows : Wing, S.-IO-S.T") 

 inches (average, 8.56); tail, 3.50-3.70 (3.(i0); culmen, 1.05-1.10 (1.09); depth of bill through base, 

 .20-.25 (.22); tiji-sus, .60-.68 (.62); middle toe, .55-.65 (.58). 



The Black Tern i.s a cosmopolitan species, coniiuon to both continents. It is dis- 

 tributed, at different seasons, in nearly all parts of Korth America; regularly and 

 abundantly in some re}.'i'>ns, occasionally and in small nnmliers in others. It is found 

 throughout Central America and Mexico, and in South America as far south at least 

 as Chili, and north to the Fur Regions and Hudson's ISay. Examides of this bird 

 were taken near Fort Eesolntion, Fort Yukon, and ^loose Fort, and it is abundant in 

 the Red River and Selkirk settlements. 



In (ireat Britain this bird is only a summer visitor, differing from all the other 

 Terns in some of its habits, seldom associating with any other species, and being 

 rarely seen on the sea-coast, and then oidy in the spring, at the time of its arrival. 

 or in the fall, when about to leave for the winter. Preferring fresh-water marshes, 

 the vicinity of rivers, and reedy ])ools, it is found in the summer only in the interioi. 

 It is rare in the north of England, and makes its appearance in the southern part by 

 the end of April or the beginning of May, and leaves early in October, being very 

 rarely seen as late as Novend)er. 



This is said to be a common bird in Sweden ; it is also abundant in Holland ami 

 in Germany, as well as in the extensive marshes of Hungary. It visits several 



