SAN LUCAS VIREO 315 



Fall. — Altlioiigli most individuals of the species breed in the Pa- 

 cific States, mainly west of the Rocky Mountains, Cassin's vireos mi- 

 grate southeastward in the fall, through Utah, Colorado, Arizona, 

 and New Mexico, to their winter resorts in Mexico. 



VIREO SOLITARIUS LUCASANUS Brewster 



SAN LUCAS VIREO 



HABITS 



William Brewster (1891) , in describing and naming this vireo, says : 



This Viieo although averaging oonsiderahly smaller thau V. s. cassinii has a 

 bill as large and stout as in V. s. alticola. In the coloring of the upper parts all 

 my spring and summer specimens agree closely with cassinii but there is a de- 

 cided and very constant difference in the color of the flanks and sides, these 

 having quite as much yellow as, but much less greenish than, V. solitarius. In 

 autumnal plumage the Lower California bird approaches autumnal specimens 

 of solitarius very closely, having the upper parts quite as bright olive gi-een, the 

 wing-bands as yellow, and the head nearly as clear ashy. There is also fully as 

 much yellow on the sides, but nmcli less greenish. These characteristics, with 

 the almost total lack of brownish beneath, distinguish it readily from young 

 cassinii. 



Mr. Brewster (1902) says of its range: "So far as known, this 

 Vireo is strictly confined to the Cape Region, where it is found at all 

 seasons of the year, although most numerously, perhaps, in summer. 

 Its breeding range extends from the coast at San Jose del Cabo, where 

 it occurs almost exclusively in cultivated grounds about houses, to 

 Miraflores and San Jose del Rancho, at both of which places it is 

 common. Only a few were seen by Mr. Frazar at Triunfo, and none 

 on the Sierra de la Laguna, while but one was taken (on April 4) at 

 La Paz, which appears to be beyond the northern limits of its usual 

 range." 



It is of interest to note that this race seems to be entirely isolated, 

 as no form of the blue-headed vireo species is known to breed in the wide 

 gap between La Paz on the south and the Sierra San Pedro JMartir 

 on the north. 



Nesting. — Mr. Brewster (1902) writes: "A nest of Y. s. lucasanus 

 containing four fresh eggs, found by Mr. Frazar at San Jose del 

 Rancho on July 15, was suspended in a fork at the extremity of a long, 

 leafless branch of an oak at a height of about fifteen feet. It is com- 

 posed chiefly of a gray, hemp-like fiber mixed with grass stems and thin 

 strips of bark. There are also a few spiders' cocoons loosely attached 

 to the bottom and sides, and apparently intended as ornaments. The 

 interior is very neatly lined with fine, wiry, reddish-brown grass cir- 

 cularly arranged. The nest measures externally 3.00 in diameter by 

 2.50 in depth ; internally, 2.00 in diameter by 1.50 in depth. The walls 

 are half an inch thick in places." 



