1914] Grinnell: Mammals and Hints of the Colorado Valley 155 



dead branches or exposed tree-tips, where the brilliant colors of the 

 male rendered each individual most conspicuous. Yet this same sort 

 of perch, because of its being a good vantage point from which to get 

 the widest survey for passing insects, was also preferred by the other 

 flycatchers, such as wood pewees and western kingbirds. No instance 

 came under my observation of the conspicuousness of the male ver- 

 milion flycatcher causing it to be molested save by human hunters. 



A half-grown juvenal was taken May 2 at this last station. The 

 species was seen nowhere else than as above stated. Eighteen specimens 

 were secured (nos. 12938-12955). 



Corvus corax sinuatus Wagler 

 Western Raven 



Ravens were to be seen at practically every point of observation 

 along our route from Needles to Pilot Knob. They were always noted 

 singly or paired and were usually quiet. No young of the season were 

 observed up to the time of our departure from the region. Ravens came 

 to notice most frequently along the river as we floated down the swift 

 current. Our boat was sometimes quietly carried into close proximity 

 to an unwitting raven as it foraged for fish on some sand bar. 



At a heronry on the California side, ten miles below Ehrenberg, 

 a pair of ravens was observed circling close over some nests which had 

 just been deserted by the startled herons. Nearby, a dead cottonwood 

 stub had under it a number of broken heron egg shells which doubtless 

 betokened a source of the ravens' food supply. The stomach of one 

 of the ravens shot contained only some mammal hair and one spider. 



In each of the three ravens secured the ' ' concealed ' ' grayish white 

 of the hind neck is much whiter and more extended than in ravens from 

 California west of the desert divide. In the latter it is ordinarily dis- 

 tinctly light gray; in the Colorado River birds it is so much lighter as 

 to give a first impression of pure white contrasted with the black 

 surface-plumage when the feathers are parted. In fact this impression 

 was so vivid that for a time in the field we thought we had secured 

 examples of Corvus cryptoh ucus. But comparison of skins shows the 

 concealed white of cryptoleucus to be actually much more snowy. And 

 there is. of course, no difficulty in distinguishing sinuatus from cryp- 

 toleucus when measurements are compared, the former being very much 

 the larger (see accompanying table). 



