° 1915 J Bangs, Dichromatic Herons and Hawk*. 4ol 



NOTES ON DICHROMATIC HERONS AND HAWKS. 



BY OUTRAM BANGS. 



In the Proceedings of the Biological Society of Washington, 

 Vol. XXV, pp. 53-58, Oberholser gives a detailed account of the 

 so-called Butorides brunescens (Lembeye) of Cuba and the Isle of 

 Pines and emphatically states his belief that it is a true species 

 quite distinct from the Cuban form of Butorides mrescens with 

 which it sporadically occurs in the two islands just mentioned. 

 He admits that in size and proportion it exactly agrees with the 

 ordinary Green Heron of Cuba. 



Theoretically I have always held the opposite opinion. There 

 is nothing about Butorides brunescens that suggests specific dis- 

 tinction to me, everything seeming to point rather to this peculiar 

 form being nothing more or less than an erythristic phase of plum- 

 age of Butorides virescens. 



Up to now, extreme examples of the brunescens phase of plum- 

 age have been recorded only from Cuba and the Isle of Pines, 

 although as stated by Thayer and myself, and by Oberholser, 

 many specimens from the Pearl Islands, Bay of Panama, show a 

 very decided approach to it, some being nearly as extreme as Cuban 

 skins. In a series of twenty-two specimens from the Pearl Islands, 

 just one half show more or less of this erythristic tendency. 

 The other half of the series (eleven skins) is made up of birds in 

 absolutely normal plumage — quite indistinguishable so far as 

 color and markings are concerned from typical examples of Buto- 

 rides virescens. 



Peters, Auk, Vol. XXX, p. 370, described at some length a young- 

 ish green heron, M. C. Z. no. 60699, taken by himself at Camp 

 Mengel, Quintana Roo, Mexico, February 7, 1912, that shows 

 decided erythrism and that closely approaches the brunescens type 

 of coloration. 



Lately while cataloguing that part of the Howe-Shattuck col- 

 lection of birds which was transferred from the Boston Society of 

 Natural History to the Museum of Comparative Zoology, in a long 

 series of Green Herons from Florida, I found one adult female in 



