56 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



are of such a nature as to bar the species from large areas, but 

 Thryomanes demands no such rigid conditions for its existence. 

 The essential environmental requisite is underbrush, afford- 

 ing shelter, and this is a condition so universally met with in 

 California that there are few regions that do not answer. 



Just one of the California forms of this species has truly 

 migratory habits, Thryomanes b. ercmopliilus. The others are 

 practically resident wherever found. It is true that this fact 

 is not generally recognized, and that there are records of sev- 

 eral subspecies from points more or less remote from the breed- 

 ing ground, but I am convinced that for the most part these 

 records are not well founded. In the extensive series of skins 

 here assembled, and in the field work incidental to the accumu- 

 lation of the large proportion of them in which the writer took 

 part, there has been no evidence evolved indicating regular 

 migrations of these birds. As evidence to the contrary, the 

 following facts may be adduced : Thryomanes b. calophonus 

 is stated to remain in winter at the northern limit of its range 

 (Oberholser, 1898, p. 441 ), which is also the northern extreme 

 reached by the genus in North America. We do not find 

 marincnsis or spilurns wandering south in winter along the 

 coast of southern California, any more than we do certain 

 other forms of comparable distribution and faunal restriction, 

 such as Pipilo maculatus falcifer, Zonotrichia leucophrys nut- 

 talli, Junco oreganus pinosus, etc. In the extensive series of 

 wrens assembled from southern California and from parts of 

 the Mohave and Colorado deserts, numbering some hundreds 

 of skins secured at all seasons of the year, there is none that 

 can be considered as typical of Thryomanes b. drymoecus, to 

 be taken as proof of a southward winter movement of this 

 form. 



Thryomanes b. crcmophilus appears to be truly migratory. 

 Data are lacking to show whether or not the breeding ground 

 is entirely deserted in winter, but the subspecies is known to 

 occupy parts of the Colorado desert during the winter months, 

 while it does not nest in that region. The birds found on the 

 Colorado Desert during winter are apparently migrants from 

 the desert mountains to the northward, and not from eastern 

 Arizona, where this wren is a common resident. Though the 

 Desert Wren has been found in winter to the eastern base 



