° 1912 J Phillips, The American Black Ducks. 295 



was evolved, a bird larger than the Savannah Sparrow of the main 

 land, and of a gray or sandy, rather than a black and brown color, 

 so that when it squatted in terror on the sand the sailing Hawk 

 was more apt to pass it by. 



It seems to me, therefore, that the evolution of the Ipswich 

 Sparrow is comparatively recent, and that the age of this species 

 may be counted by the paltry fifty thousand years or so that have 

 elapsed since the last glacial period. 



A RECONSIDERATION OF THE AMERICAN BLACK 



DUCKS WITH SPECIAL REFERENC E TO 



CERTAIN VARIATIONS. 



BY JOHN C. PHILLIPS. 



There are several species of primitive ducks which for many 

 reasons are of peculiar interest, on account of their remarkable 

 geographical distribution and mutual interrelationship. This 

 group of species is composed of Anas fulvigula, Anas tristis, Anas 

 diazi, Anas ivyviUiana and Anas laysancnsis. Most of these are 

 poorly represented in collections and this fact has led to certain 

 misconceptions. It is the purpose of the following notes to point 

 out some of these mistakes, and to say a few words about individual 

 and sexual variation. 



To begin with I wish to call attention to the principal difficulty 

 in the proper understanding of these local races; this is the presence 

 of a sexual difference in plumage, increasing probably with age, 

 and comparable, with that of the Hawaiian duck (Anas wijviUiana) . 

 In this way all these related species can be separated from A. 

 tristis in which the sexes are similar. At first I thought that this 

 sex difference was confined to A. diazi and I started to limit these 

 notes to the latter species, but as more specimens turned up I 

 thought it better to consider all the American Black Ducks. 



