218 U. S. NATIONAL MUSEUM BULLETIN 211 



Young males and females, during their first winter, are both some- 

 what duller in color than are the adult females at that season. 



Ridgway (1902) describes the adult winter plumage of the male as 

 similar "to the summer plumage, but the orange or orange-yellow 

 duller, especially on upper parts, where more or less obscured by a 

 tinge or wash of olivaceous; scapulars and inter-scapulars margined 

 terminally with light olive or olive-grayish; tertials more broadly 

 margined with white." 



Behavior. — Sennett (1879) noted that these orioles "were contin- 

 ually peering about the thatched roof of our house and arbors adjoining 

 for insects. They were more familiar than any of the other Orioles 

 about the ranch." And Baird, Brewer, and Ridgway (1874), state on 

 information received from Captain McCown : 



When met with in the woods and far away from the abodes of men, it seemed 

 shy and disposed to conceal itself. Yet a pair of these birds were his constant 

 visitors, morning and evening. They came to the vicinity of his quarters — an 

 unfinished building — at Ringgold Barracks, and at last became so tame and 

 familiar that they would pass from some ebony-trees, that stood near by, to the 

 porch, clinging to the shingles and rafters, frequently in an inverted position, 

 prying into the holes and crevices, apparently in search of spiders and such insects 

 as could be found there. From this occupation they would occasionally desist, 

 to watch his movements. He never could induce them to partake of the food he 

 offered them. 



Enemies. — Sennett's hooded oriole is often imposed upon by the 

 dwarf cowbird and the red-eyed cowbird, principally the latter, and 

 the eggs of both species are sometimes found in the same nest. Out 

 of the 16 nests observed by FriedmaDn (1925) near Brownsville, one 

 held an egg of the dwarf cowbird and two of the oriole, and three con- 

 tained eggs of the red-eyed cowbird. 



DISTRIBUTION 



Breeding range. — Sennett's hooded oriole breeds from Southern 

 Texas (Rio Grande City, Port Isabel) south along the Gulf coastal 

 plain to southern Tamaulipas (probably Paso del Haba). 



Winter range. — Winters throughout its range south to northern 

 Guerrero (Taxco, Iguala) and Morelos (Cuernavaca). 



Migration. — The data deal with the species as a whole. 



Early dates of spring arrival are: San Luis Potosi — Valles, March 24. 

 Tamaulipas — Rancho Rinconada, March 5. Nuevo Le6n — Linares, 

 March 5. Sonora — Tesia, March 21; Baja California — Santo Do- 

 mingo, February 28. Texas — Hidalgo and Brownsville, March 12 

 (median of 9 years in Cameron County, March 15). New Mexico — 

 Carlsbad Cave region, March 24. Arizona — Tucson, March 14 

 (median of 13 years, March 25). California — Los Angeles County, 

 March 5 (median of 32 years, March 20) ; Santa Barbara, March 14. 



