ANNA'S HUMINIINGBIRD 379 



cease to show mucli interest in unfamiliar brightly colored objects, 

 unless it may be in times of food shortage, or when invading new 

 territory where exploration must be carried on to locate its floral 

 resources. Among familiar surroundings, memory for location un- 

 doubtedly guides the hummingbird to a large degree in its feeding. 



As a general rule, hummingbirds prefer flowers of tubular form 

 and are comparatively indifferent to composites and double flowers, 

 such as roses. Within certain limits, size seems to be of little moment. 

 One of the most valuable plants to Anna's hummingbird, especially, 

 is a naturalized introduction from South America, the tree tobacco 

 {Nicotiana glauca). This tall, sparse-foliaged, drought-resistant 

 shrub bears a profusion of narrowly tubular blossoms practically 

 throughout the year. Somewhat sensitive to cold, it is found only 

 in the warmer parts of California, As an example of the humming- 

 birds' frequent disregard of bright coloring, they will probe the 

 greenish-yellow newly opened flowers of this plant in preference to 

 the purer yellow mature blossoms, which evidently contain less nectar. 

 The greatest concentration of hummingbirds is seen about the tall, 

 treelike flower stalks that culminate the life cycle of the common 

 "century plant" {Agave americana) , abundantly grown in California. 

 The numerous greenish-yellow blossoms are dull-colored, but evi- 

 dently they offer a rich store of nectar. Various species of eucalyptus, 

 some of which bloom in winter, also attract large numbers of hum- 

 mingbirds. The State of California must now be capable of sup- 

 porting a much larger population of these birds than would have 

 been possible under primitive conditions. 



At times when their natural food is scarce, hummingbirds will 

 gladly avail themselves of offerings of saturated sugar solution, which 

 seems to be preferred to commercial honey. When flowers are plenti- 

 ful and hummingbirds not too numerous they pay less attention to 

 the artificial food than do the orioles and house finches, which are 

 equally fond of sweets and not so well fitted to extract them from 

 the flowers. It is during the latter half of the year that the hum- 

 mingbirds will make most frequent use of sugar syrup in order to 

 compensate for the comparative scarcity of flowers, though when the 

 habit is once formed it may be continued even through spring. Visits 

 are made at intervals during the day, perhaps only half-hourly when 

 the temperature is high, but with increasing frequency toward even- 

 ing, the height of this activity occurring between sunset and ten 

 minutes after, when feeding ceases for the day. The use of clear 

 glass vials affords an opportunity to observe the hummingbird's 

 manner of drinking. When the liquid is out of reach of the bill, it 

 is lapped up by rapid movements of the tongue, which can be ex- 

 tended an additional distance equal to the length of the bill. Should 



