682 



STERNA HIRUNDO, COMMON TERN. 



to preseut it. This I regret the more since it does not seem to be generally known, 

 and even quite diverse accounts of its winter dress are given by authors. Teiiiniiuck, 

 for example, says that in winter the adults do not lose the black of the crown ; " elie 

 est seulemeut plus turne." Other authors ascribe to it a condition of phuuage very 

 similar to that presented by S.fornicri or macrura, and I have myself little doubt but 

 that such is really their condition at that season. Naumann, one of the most exhaust- 

 ive describers of the changes of plumage of birds, is nnable to give a verj- satisfoctory 

 account of this plumage, for the reason, as he says, "that so long as the winter range 

 of habitat of this species remains unknown to us, it vrill always be difficult to give au 

 account of the winter plumage of the fully moulted bird." He says, however, that 

 the forehead and cheeks are white, more or less variegated wiih black ; the middle of 

 the crown white, lightly spotted or streaked with black; occiput and nape almost 

 wholly black. In other respects, I think that the upper and under parts will both be 

 found to be lighter than in summer, the latter especially approaching to the pure 

 white of the young bird ; the tail will be shorter and less deeply forked ; the bill and 

 feet duller red, the former more invaded by the black of the terminal portion. Audu- 

 bon says that "in winter the bill is black, with the base pale orange and the tip yel- 

 lowish; the feet orange-yellow. The colors are as in the adults, the forehead white, 

 the rest of the head dusky, the upper parts having the feathei's slightly edged with 

 lighter." 



Oilier varialions. — These consist, as nsnal in the subfamily, chiefly in the total size, 

 individuals varying considerably in this respect. (See above measurements.) I scarcely 

 find any variations in color worth noticing in specimens of equal ages at coriesponding 

 seasons. The amount of black on the bill may be increased or diminished, but I have 

 never seen it equal in amount to that of S. fosteri or longipennis, nor yet entirely absent, 

 as is usually the case with S. macrura. 



Coyirparison with aUiid species. — The present being the typical species of the group, ifc 

 is taken as the standard with which to compare other species ; and the diftereuces of 

 each of them from it will be found under their respective heads. 



Deglaud, in his Ornithologie Europe6nne, speaks of the occurrence of a hybrid of 

 this species and the S. macrura partaking in a varying degree of the characters of 

 either parent. Though I have never met with a specimen which I could not unhesi- 

 tatingly refer to one or the other si^ecies, it is not improbable that hybrids should 

 reallj^ occur. 



Comparison of American and European bird. — Being desirous of determining definitely 

 the relationships of our bird to that of Europe, I procured for examination au exten- 

 sive series from both countries, comprising some fifty specimens. These I carelully 

 compared in their most minute details, and in no respect could I detect the slightest 

 discrepancy. This is contrary alike to late high authority on the subject and to my own 

 preconceived ideas. It would be difficult to say upon what grounds the validity of 

 S. " icilsoni" has been maintained, since no definite characters have ever been laid down 

 whereby it may be separated from S. hirundo. The American bird was first distin- 

 guished from the European by Bonaparte, in 1838, in his Comparative List; but no 

 diagnosis is offered. -S'. '^icilsoni" is one of several species inlroduced by this aurhor 

 in the same work, for the distinguishing of which from their European i-epresentatives 

 he seems to have relied upon some preconceived theory of gtogrisphical distribution, 

 rather thau upon any characters afforded by the birds theniselves. I jiresent the 

 detailed measurements of five American and five European birds, taken at random from 

 a large series. It will be noticed that in no respect do the dimensions of the birds from 

 the two continents present greater differences than are found in the several examj)les 

 from either. 



* Inches and hundredths. 



