416 BULLETIN 17 6, UNITED STATES NATIONAL MUSEUM 



Behavior. — Henshaw (1877), with his original description of 

 Allen's hummingbird, makes the following comparison of this species 

 with the rufous hMmmingbird : 



I am in possession of but few notes bearing upon the habits of this Hummer. 

 Mr. Allen remarks incidentally in a letter th'at the Green-backs are much the 

 livelier and more active of the two, keeping constantly in the open, and always 

 perching upon the most prominent dead twigs they can find. Their extreme 

 shyness, as contrasted with the unsuspicious nature of the Rufous-backed, is 

 quite remarkable. They seem to possess a larger share th'an usual of the 

 courage and pugnacity which is so constantly displayed in birds of this 

 family. Not only do they always come off the victors when chance encounters 

 take place between them and the Rufous-backs, but Mr. Allen has seen a pair 

 attack and piit to rout a Red-tailed Hawk; while, as he remarks, "Sparrow- 

 Hawks have no chance at all with them." He has often seen the little fellows 

 in hot chase after these latter birds, and their only care seemed to be to get 

 out of the way as soon as possible of foes so determined. 



Each male seems to claim a particular range, which he occupies for feeding 

 and breeding purposes, and every other bird seen by him encroaching on his 

 preserve is at once so determinedly set upon and harassed that he is only too 

 glad to beat a hasty retreat. During their quarrels these birds keep up an 

 incessant, sharp chirping, and a harsh, rasping buzzing with their wings, which 

 sounds very different from the low, soft humming they make with these while 

 feeding. Every action and motion at such times indicates that they are as mad 

 as can be ; tlie poor Anna Hummers have to get out of their way pretty quickly 

 at any time, but especially when they encroach on their breeding grounds. The 

 males very often have quarrels among themselves, and are then very noisy, 

 while the females are more orderly and quiet; but even they have occasional 

 little misunderstandings with each other, especially when a pair meet while 

 feeding on the same bush; one generally vacates the premises very quickly, and 

 as soon as she does all becomes quiet again. 



Field marks. — The male Allen's hummingbird looks very much 

 like the male rufous, but can be distinguished from it by the large 

 amount of green in the back. Both sexes can be distinguished from 

 other California hummingbirds, except migrating rufous, by the large 

 amount of rufous in the plumage, especially in the tail. The female 

 Allen's is practically indistinguishable, in the field, from the female 

 rufous hummingbird ; only a close comparison of the tails will distin- 

 guish tjie two species. The difference in the color patterns of the 

 tails of the two females is described, as quoted from Ridgway (1911), 

 under the field marks of the rufous hummingbird ; but the difference 

 seems to be very slight. The best distinguishing character, which 

 might under favorable circumstances be seen in the field, is the 

 Avidth of the two outer tail feathers, as illustrated in Henshaw's cut 

 (1877) ; in S. nifus the four lateral rectrices are "successively grad- 

 uated in size, the outer the smallest"; and they are of normal hum- 

 mingbird width ; whereas in 8. alleni the two outer feathers are "very 

 narrow, linear, the outer nearly acicular," a well-marked difference. 



