ROCKT MOUNTAIN YELLOW "WARBLER 185 



DENDROICA PETECHIA MORCOMI Coale 

 ROCKY MOUNTAIN YELLOW WARBLER 

 HABITS 



This is another race that was described many years ago by H. K. 

 Coale (1887) but has only recently been accepted by the A.O.TJ. 

 Coale gave it its scientific name in honor of J. Frean Morcom and 

 called it the western yellow warbler. The following remarks by 

 Dickey and van Rossem (1938) tell the story very well : 



The race of yellow warbler summering in the Great Basin and Rocky Mountain 

 regions of the United States of late years has been generally overlooked and 

 has been synonymized commonly with aestiva or, in part, with hreivsteri. 

 Although not a well differentiated form, its characters are readily apparent in 

 series, and there is no reason why it should not be accorded equal standing 

 with the races currently recognized. The underparts of the males are heavily 

 marked, and in this respect morcomi is not distinguishable from aestiva, 

 Dorsally, however, morcomi is darker and less yellowish green, particularly on 

 the interscapular region. The females are, age for age, more buffy (less yel- 

 lowish) below and darker and more grayish above than the females of aestiva. 

 In comparison with hrewsteri, morcomi (particularly the bill) is larger, and 

 the males are more heavily streaked below. The range of morcomi is the Rocky 

 Mountain region of the United States, north to Wyoming and Idaho, west to 

 the eastern slope of the Sierra Nevada, and south (in the western part of its 

 range) to Mammoth, Mono County, California. We have not seen material from 

 the southern Rocky Mountains; so we cannot state the southern limits in 

 that region. 



They call it a "common spring and fall migrant and winter visitant 

 in the lowlands," of El Salvador. "Dates of arrival and departure 

 are August 1 and April 9." 



Angus M. Woodbury has sent me a copy of the manuscript for "The 

 Birds of Utah," by Woodbury, Cottam, and Sugden, from which I 

 infer that the haunts, nesting, and other habits of the "western yellow 

 warbler," as they call it, do not differ materially from those of the well- 

 known eastern bird. They say of its status in Utah: "This yellow 

 warbler is a common summer resident from early May to late August, 

 the vanguard sometimes reaching here in late April and stragglers 

 sometimes lingering into September, the latest record being September 

 23. It is primarily a bird of the riparian growths along water edges, 

 either of streams, ponds or lakes or irrigated areas, particularly of the 

 valleys and lower canyons, but occurs higher in the canyons in suitable 

 habitat up to at least 8,000 or 9,000 feet. It does not seem to be 

 attracted to large trees such as cottonwoods, but seems to prefer the 

 more leafy shrubbery and small trees of developmental stages in 

 ecological succession. In migration, it sometimes leaves this niche and 

 may occasionally be found elsewhere. * * * 



"In nesting, it is usually found in a bush, chaparral or small tree 

 stratum, seldom going to the ground or to the tops of trees. Its nests 



