192 BULLETIN 195, UNITED STATES NATIONAL MUSEUM 



logs and stumps, brought clown by the high water. It is among the 

 tangled roots and natural cavities of these stumps that this wren 

 nests." 



The eggs of the Nicasio wren are apparently no different from 

 those of the other races of this species. The measurements of 26 eggs 

 average 1G.7 by 12.9 millimeters; the eggs showing the four extremes 

 measure 18.5 by 13.5, 16.1 by 13.9, 14.6 by 12.5, and 1G.3 by 11.9 

 millimeters. 



THRYOMANES BEWICKII SPILUUUS (Vigors) 



VIGORS'S WREN 



HABITS 



This was the first of the western races of Bewick's wrens to be de- 

 scribed and named. The other races have all been separated since 

 about 1880; in our first Check-list, published in 1886, this and Baird's 

 wren were the only western races included. The above name then 

 covered all the wrens of this species inhabiting the Pacific slope of 

 the United States, Baird's wren occupying the southwestern desert 

 regions. This old name is now restricted to the wrens of a narrow 

 range in west-central California, from San Francisco Bay to northern 

 Monterey County. 



The distinguishing characters are thus described by Dr. Oberholser 

 (1898) : '"''Thryomanes heivickii spilurus may be distinguished from 

 hewickii by its duller brown upper surface, darker sides and flanks, 

 broader superciliary stripe, shorter wing and tail, rather longer mid- 

 dle toe and tarsus. It may be separated from charienturus by darker, 

 decidedly more ruf escent flanks and upper parts and by shorter tail ; 

 from drymoecus by the much darker color of sides, flanks and upper 

 surface." 



Mr. Swarth (1916) says of the characters of spilurus: "Most nearly 

 like T. h. marinensis^ whose range adjoins that of spilurus at the north, 

 but of lighter brown coloration dorsally, and of slightly greater size. 

 Compared with drymoecus it is brighter reddish above. From chari- 

 enturus it differs in deeper red coloration, and in different propor- 

 tions. In spilurus the tail is slightly shorter than the wing ; in charien- 

 turus the tail is longer than the wing." He admits that it is interme- 

 diate in range and in characters between marinensis and charienfurus, 

 both of which occupy much more extensive ranges. 



Edwin V. Miller (1941) has published an interesting paper on the 

 habitats of several western races of this species and a long account 

 of the behavior of Vigors's wren, from which much of Avhat follows has 

 been taken, though space will not permit as full quotations as the ma- 

 terial warrants. He says in a general way : "There are but few fea- 

 tures of habitat common to all the races of Bewick wrens. Thick 

 plant growth of a kind that will furnish the proper insect food seems 



