KENTUCKY WARBLER 235 



Biographical References 



(i) W. L. Kells, Grinnell's Water-Thrush (in British Columbia), Nidolo- 

 gist, I, 1894, 42, 58. (2) E. W. Nelson, Report on Nat. Hist. Coll. made in 

 Alaska, 204 (the bird is given as Sciurus novcboraccnsis) . 



Genus OPORORNIS Baird 



Compared with Geothlypis, Oporornis (taking O. agilis as the 

 type) has the wing much longer and more pointed, the tail decidedly 

 less rounded. The wing is at least three and a half, instead of two and 

 three-fourths times as long as the tarsus, the outer primary is usually 

 the longest, the outer tail-feathers are but little the shortest, the hind- 

 toe is as long as its claw. 



While admitting the characters which distinguish Oporornis agilis 

 from Geothlypis most systematists have treated Oporornis as a sub- 

 genus of Geothlypis because of the existence of several species pos- 

 sessing intermediate characters. The attempt, however, to force 

 Oporornis into Geothlypis negatives any description emphasizing the 

 well-marked structural features which prevail in that genus and, at 

 the same time, prevents the proper description of the generic char- 

 acters which distinguish Oporornis. It seems desirable, therefore, to 

 recognize both genera and to place the intermediate species with those 

 forms to which they appear to be most nearly related. Of these inter- 

 mediate species the Kentucky Warbler has invariably been placed in 

 Oporornis, while the Mourning and Macgillivray's Warbler have 

 usually been grouped with Geothlypis. Mr. Ridgway, however, on the 

 basis of their general coloration, more pointed wing and longer outer 

 primary, includes them in Oporornis and I have little doubt of the cor- 

 rectness of his decision. 



Under this ruling the genus contains four species, three of which 

 are eastern and one western in its distribution. 



Kentucky Warbler 



OPORORNIS FORMOSA (Wils.) Plate XVIII 



Distinguishing Characters. — The Kentucky Warbler may always be known 

 by its entirely yellow underparts, absence of white in wings and tail, yellow 

 line over the eye, black or blackish on crown and sides of throat. Length 

 (skin), 5.00; wing, 2.65; tail, 2.00; bill, .45. 



Adult ($, Spring. — Crown black more or less tipped with ashy, line over 

 and around back of eye yellow, rest of upperparts, wings and tail olive-green, 

 outer vane of outer primary grayish, bend of wing yellow; underparts from 

 chin to crissum bright yellow, lores, cheeks and band at side of throat black. 



