VIGORS' S WREN 193 



to be the chief requisite. The kinds of plants in one part of the range 

 of the species may be totally different from those in another part. The 

 wrens may be found in trees more than 100 feet high or in brush not 

 more than 3 feet high. In the Upper Sonoran Life-zone they are 

 most abundant where the plant growth is thickest. They are par- 

 ticularly noted for their preference for mixed brush." 



It appears from his accounts, and the statements of others, that the 

 western races are less domestic than the eastern race, and are more 

 abundant in brushy areas away from human habitations. Chaparral- 

 covered hills abound throughout the range of Vigors's wren, and it is 

 there that the wrens are found in greatest numbers, where they find 

 an abundant food supply and suitable nesting sites. But they are 

 also found to some extent in other situations. '"On the north-facing 

 slope" of Strawberry Canyon in Berkeley, "the wrens are common, 

 being found in chaparral, mixed brush and oak, and in pure stands 

 of Monterey cypress and Douglas fir, without underbrush. In the 

 chaparral association, baccharis is the dominant plant, forming dense 

 stands of 4 to G feet in height. In the mixed brush and oak region 

 the height of the plant cover is anywhere from 1 to 30 or 40 feet." 



Mr. Miller (1941) determined to his own satisfaction that the males 

 establish and maintain definite territories during the breeding season, 

 and perhaps to a less extent at other seasons ; he says : 



Bewick Wrens are found throughout the year either singly or in pairs. Most 

 commonly the males appear on territories in the early spring and are mated 

 shortly afterward. Males of T. &. spilurus show territorial reactions toward 

 other males at any time of the year, although much more frequently in the spring. 

 Females show no sucli reactions toward males, at least, and probably have no part 

 in the defense of territory. Males and mated pairs have territories in the spring 

 and may possibly have them in the winter. The territories of several wrens were 

 mapped ; they proved to be about 50 yards wide by 100 yards long. * * * The 

 limits of these territories did not vary more than a few feet from day to day. The 

 males of these areas exhibited strong reactions toward other males adjacent to 

 them. When two males happened to meet on a boundary, they would stop forag- 

 ing, sing, and give harsh vocal utterances, and follow each other along the edge of 

 their territories. Males would often stop foraging and hurry to their boundaries 

 when they heard another male nearby. 



Nesting. — The same observer states that "Bewick Wrens' nests are 

 placed in secluded cavities in or near the ground. Each nest has a well 

 defined cup of soft materials and usually has a base of small twigs. 

 Most nests are open above ; rarely they are arched over the top. The 

 male may develop slight nest-building instincts before he is mated, but 

 in most instances nests are not built until the female is present. Both 

 mates may build the nest, although the male works sporadically, and 

 the female often builds alone. Usually only one nest is built, although 

 some authors state that several are sometimes begun. * * * The 

 nest may be built in 10 days and the eggs may be laid in 6 days." 



