88 BULLETIN 135, UNITED STATES NATIONAL MUSEUM 



In the Juvenal plumage the sexes are much alike, but the crown 

 is darker in the young male and the dusky shaft streaks on the throat, 

 breast and wing coverts are more conspicuous in the young female. 

 The Juvenal plumage closely resembles that of the adult female; but 

 the crown and back are somewhat lighter brown, the feathers of the 

 back and scapulars are edged or tipped with buffy, and the buff 

 feathers with dusky shaft streaks give the throat and breast a striped 

 appearance; the buffy, lesser wing coverts also have dusky shaft 

 streaks. The buffy edgings of the dorsal feathers generally wear 

 away before October, leaving the back clear biown; but the juvenal 

 wing coverts are more or less persistent, especially in females, until 

 the first postnuptial molt the next summer. At this complete molt 

 in August young birds become indistinguishable from adults. There 

 is apparently no well-marked seasonal difference in the plumages of 

 adults, but the sexual difference becomes apparent during the first 

 spring and is well marked thereafter. 



It now seems to be generally conceded that the dark form, known 

 as the Cory least bittern, Ixohrychus neoxenus (Cor}'), is not a distinct 

 species, but a case of melanism or erythrism, such as occasionally 

 occurs in other species of birds and animals. Some 30 specimens 

 have been recorded; the largest numbers have been taken in Florida 

 and Ontario; but it has also been taken in Massachusetts, New York, 

 Ohio, Illinois, Michigan, and Wisconsin. It is a striking case of high 

 pigmentation which seems likely to turn up almost anywhere within 

 the range of the least bittern, and it is sometimes combined with traces 

 of albinism. It should not be called a color phase of a dichromatic 

 species, as it occurs too rarely and irregularly. A dichromatic species, 

 it seems to me, is one in which two color phases occur regularly, such 

 as in the reddish egret, the parasitic jaeger, and the screech owl. 



Since writing the above I have been much interested in what Oscar 

 E. Baynard has told me about the Cory least bittern. He has had 

 considerable field experience with it, has found several nests and is 

 firmly convinced that it is a distinct species. He says that these dark 

 colored birds never mate with ordinary least bitterns, but always with 

 birds of their own kind, breeding true to color. He also says that 

 the downy young are coal black, "as black as young rails," that all 

 the young in the nest are also black and that he has never seen 

 any buff colored young in the same nest with the black ones. If 

 these facts hold true in all cases they are strong evidences of the 

 validity of the species. 



Food. — The least bittern is an active feeder, walking stealthily 

 about in the marshes and bogs, and hunting for the various forms of 

 animal life found in such places. One that Audubon (1840) had in 

 captivity was "expert at seizing flies, and swallowed caterpillars, and 

 other insects." He has also found "small shrews and field mice" in 



