The Western Red-tailed Hawk 



to catch the glint of authentic rufous from the upper surface of the tail. 

 Young birds do not show the red, but are obscurely barred instead. 

 Of their identity we can be sure only through their association with 

 adults, or else by "elimination." Redtails, moreover, exhibit many puz- 

 zling guises. Both melanism and albinism are common, with erythrism, 

 that is, undue reddening of plumage, not unknown. Occasionally speci- 

 mens are found which are black as coals, and these may be known with 

 certainty only by measurements and averages. The strength of the wind 

 or direction of flight are also important elements in sight determination 

 of sky-high birds. A Western Redtail presents, normally, a rounded 

 wing-tip of separated quills, of which the 4th primary is the longest. 

 But a bird coming down against the wind has a sharply pointed wing. 

 Careful scrutiny shows that as often as a Redtail comes down in this 

 fashion, it reefs the wing by furling the first three primaries under the 

 fourth — "as though by means of invisible brails," our nautical man says. 

 The change of pattern thus effected is very striking, and the possible 

 variations of outline should be borne in mind in the study of all sailing 

 birds. 



The devotee of binoculars, moreover, will witness many pretty wing- 

 plays and perchance some thrilling aerial contests, if he follows the for- 



Taken in Imperial Valley 



Photo by the Author 



A NEST IN THE DESERT 

 THE HOST TREE IS the ocatilla {Fouquieria splendens) 



l679 



