580 BULLETIN 203, UNITED STATES NATIONAL MUSEUM 



GEOTHLYPIS TRICHAS INSPERATA Van Tyne 



BROWNSVILLE YELLOWTHROAT 



CJONTBIBUTED BY ALFRED OtTO GrOSS 



HABITS 



The Brownsville yellowthroat was described by Josselyn Van Tyne 

 (1933) from an adult male secured in the Rio Grande Delta below 

 Brownsville, Tex., on June 11, 1930 : 



Subspeciflc characters. — Similar to Oeothlypis trichas trichas (Linnaeus) but 

 bill larger, forehead more whitish, and general coloration paler. Compared 

 with Oeothlypis triclias occidentalis Brewster it is smaller (wing of male 55-56 

 mm. instead of 55-60 mm. ) but has a larger bill. The belly and flanks are more 

 whitish, but the forehead is less extensively white. Compared with Oeothlypis 

 trichas brachidactyla (Swainson) it is paler and has a shorter wing but an even 

 larger bill. The ninth primaiy of insperata is shorter than the fourth, instead 

 of longer as in brachidactyla. Two juveniles of the new form, taken June 2 and 4, 

 are much paler and have larger bills than any of a series of brachidactyla with 

 which I have compared them. 



Oeothlypis trichas insperata has the ninth primary shorter than the fourth, 

 as in Oeothlypic trichas ignota Chapman, but is much paler and has a very 

 much larger bill. The larger bill alone is sufficient to separate insperata from 

 the Pacific coast forms. 



The Brownsville yellowthroat is known only from the type locality. 

 It leaves the region during the winter but its winter home is not at 

 present known, nor is anything known of its nesting habits. 



GEOTHLYPIS TRICHAS MODESTA Nelson 



SAN BLAS YELLOWTHROAT 

 Contributed by Alfred Otto Gross 



HABITS 



The San Bias yellowthroat was described by E. W. Nelson in 1900. 

 The description of a male taken at San Bias, Tepic, Mexico, June 12, 

 1897, is as follows: "Smaller than typical Gl^eothlyjns] trichas from 

 the eastern United States, with the green of back darker, more brown- 

 ish olive and brownish flanks ; black frontlet and white border to same 

 nearly as in Oeothlypis trichas oocidentalis. * * * The young as 

 well as the adults are distinguishable by their dark color." 



A. J. Van Rossem (1930) states: "In typical form modesta is a dark 

 colored race. It is much like Oeothlypis trichas sinuosa of the San 

 Francisco Bay region, but is slightly grayer (less olive) and has a 

 longer tail and decidedly larger bill." Were it not for the larger bill 

 it would be difficult to distinguish these two races, although their 

 ranges are separated by a gap of over a thousand miles. 



