1914] GrinneU: Mammals and Birds of the Colorado Valley 211 



There is also a skin in the Museum (no. 4287) taken by J. G. 

 Cooper at Fort Mohave, January 22, 1861. 



As there are no known characters by which to recognize house 

 wrens breeding in the Great Basin region from those on the Pacific 

 coastal slope, there is no way of deciding where those individuals win- 

 tering in the Colorado Valley come from. But it is most likely that 

 they hail from the interior somewhere, as do practically all of those 

 birds where this point can be definitely determined. 



Telmatodytes palustris plesius (Oberholser) 

 Western Marsh Wren 

 Observed only in dense but low vegetation such as tules, along 

 lagoons in the river bottom. A single example was seen and secured 

 (no. 13846) on the California side at the lower end of Chemehuevis 

 Valley. March 11. Near Riverside Mountain March 17 several were 

 seen, and one secured (no. 13847). On the Arizona side a mile or 

 so below Ehrenberg, March 25 to 29, there were many around a series 

 of ponds. Nothing was seen of the species after the latter date. Since 

 no old nests or other indications of breeding were detected, it is not 

 to be presumed that marsh wrens are more than winter visitants to 

 the Colorado Valley. 



Auriparus flaviceps flaviceps (Sundevall) 

 Verdin 

 The most numerous and widespread resident species of bird in the 

 whole region. The only essential condition for the presence of this 

 species appeared to be stiff-twigged thorny bushes or trees of some 

 sort. This requisite was met with in a variety of situations, as in 

 the screwbeans of the first bottom, mesquites of the second bottom, 

 and catclaw, ironwood, palo verde and daleas of the desert washes. 

 The birds appeared to have already paired off by the latter half of 

 February; each pair had a particular beat or forage area, focussing 

 at one or more nests. Nests were occupied, at least as roosting places, 

 throughout the season, and as nests were not constructed in other 

 than the thorny bushes above named, the local range of the species 

 was predetermined. While the birds were often seen in willows, 

 arrowweed, and even low shrubs of Atriplex and sandburr, these were 



