14 



NORTH AMERICAN FAUNA 65 



Series of white-winged doves were collected in Mexico on March 

 28-30 near San Bias, Nayarit, and on April 1, 1960, south of 

 Escuinapa, Sinaloa. Study of these specimens, in addition to field 

 observations on their distribution, habitat, and habits, showed clearly 

 that at least two different populations were present. Most of the 

 collecting was done in or near the mangrove swamps, and most of the 

 specimens were of a darker population that was breeding in that 

 habitat. The others seen were in drier upland habitats, were in flocks, 

 were fat, and their gonads were little, if any, enlarged. The latter 

 birds were obviously winter residents or migrants, and were identified 

 as mearnsi. The darker breeding race has not been reported previously, 

 so it is described as: 



Zenaida asiatica palustris, new subspecies 

 San Bias White-winged Dove 



CHARACTERS 



Nearest to Z. a. mearnsi (Ridgway, 1915) in size, but darker than 

 that race, and with a shorter bill. It is darker in coloration and has 

 shorter wings and tail than the Tres Marias Islands population 

 described beyond. 



DESCRIPTION 



Type, U. S. Nat. Mus. (Fish and Wildlife Service collection) No. 

 481591, adult male, breeding, near San Bias, Nayarit, Mexico, March 

 29, 1960, collected by George B. Saunders, collector's number 2672. 

 Crown and nape between vinaceous drab and dark vinaceous drab; 

 back Front's brown; tertiaries Saccardo's umber to cinnamon brown; 

 middle rectrices between Front's brown and mummy brown; breast 

 nearest Saccardo's umber; belly pale ecru drab to smoke gray; and 

 flanks light quaker drab. 



Frincipal differences of diagnostic value are: palustris males average 

 a shorter bill than mearnsi, but differentiation of these races is chiefly 

 on the basis of the darker color of both sexes of palustris. In compar- 

 ison with the Tres Marias Islands population described beyond, 

 palustris has a shorter wing and is darker in color. 



MEASUREMENTS 



Males (22 specimens, mostly breeding) : wing 158.0-169.0 mm. (av. 

 163.2), tail 109.-123.6 (117.2), culmen 19.0-23.0 (20.7). Females 

 (20 specimens, mostly breeding): wing 153.5-166.0 mm. (av. 159.5), 

 tail 107.0-117.0 (112.2), culmen 19.8-23.0 (21.4). 



RANGE 



The specimens of palustris examined in this study were from the 

 mangrove swamps near San Bias, Nayarit, and northward to near 



