ANNA'S HUMMINGBIRD 381 



hummingbirds a somewhat nomadic existence, aside from true migra- 

 tions. Perhaps this instinct for change has become so strong in the 

 nonmigratory Anna's hummingbirds that they are unable to remain 

 in one locality permanently. The sugar syrup containers maintained 

 for their use have been visited by a constantly changing succession 

 of individuals, some remaining only a few days, a few for a period 

 of months, but all have eventually felt some urge more potent than 

 the desire for a sui'e and easy living. 



Behavior. — The flight of the hummingbird resembles that of no 

 other bird, but rather that of certain insects, such as dragonflies or 

 hawk moths, though stronger and swifter. Some of the earlier orni- 

 thologists expressed doubt of any bird's ability actually to fly back- 

 ward, suggesting that the hummingbird's withdrawal from the 

 depths of a tubular flower was accomplished by a forward flirt of 

 the tail. A little careful observation would soon remove any skep- 

 ticism as to its ability to easily fly backward, sidewise or in any other 

 direction. While the tail is rhythmically vibrated forward and back- 

 ward as the bird probes the flowers, it can be seen that its movements 

 are not at all related to the backward flight, and that it is, in fact, 

 seldom widely opened. 



A hummingbird's wings are in almost uninterrupted motion while 

 it is in the air; occasionally it will glide for an instant while in rapid 

 flight. The amplitude of the wing beat is variable, but it often de- 

 scribes an arc of nearly 180° when the bird poises in the air. Some- 

 times the wings seem not to rise above the level of the back, but 

 when the bird hovers over a cluster of upturned blossoms they may 

 travel through the upper portion only of the complete arc. The con- 

 fidence and sureness with which a hummingbird threads its way 

 through a maze of twigs without injury while apparently devoting 

 all its attention to the flowers cause one to admire, but its instant 

 coordination of perception and movement can perhaps best be appre- 

 ciated by noting the ease and certainty wath which it thrusts its bill 

 into a small tubular flower blown by a gusty wind. 



That the flight of the hummingbird is by no means effortless, how- 

 ever, may be realized on a hot day, when one of them, returning to 

 its shaded perch after an extended sortie, will sit for a minute or 

 two with wade-open bill, panting with a violence that shakes its 

 entire body. Though an immense amount of unnecessary flying is 

 done, apparently in sport, the obtaining of food is evidently listed 

 under the heading of work, and a hummingbird will seldom overlook 

 an opportunity to perch, even to the extent of hanging almost upside 

 down while reaching into a flower. The only sound produced by 

 the normal flight of either sex of Anna's hummingbird is a low hum, 

 which rises in volume and pitch when the speed is accelerated and 



