240 HUMMINGBIRDS. 



the gummy secretion of the bird's salivary glands. Eggs^ four to six, white, 

 •80 X -50. 



It is unnecessary to give any aids to the identification of a bird as 

 well known as the Chimney Swift, or, as it is more frequently called, 

 " Chimney Swallow." It is not, however, a Swallow, but a Swift, and 

 its structural relations are with the Hummingbirds and not with the 

 Passerine Swallows. 



Few sights in the bird-world are more familiar than the bow-and- 

 arrow-like forms of these rapidly flying birds silhoueted against the sky. 

 They are most active early in the morning and late in the afternoon, 

 when one may hear their rolling twitter as they course about overhead. 

 Sometimes they sail with wings held aloft over their backs, and some- 

 times, it is said, they use their wings alternately. It is a common 

 thing to see a trio of birds flying together, but it has never been ascer- 

 tained that the Chimney Swift is polygamous. 



In some localities Chimney Swifts congregate in large flocks, mak- 

 ing their headquarters in a disused chimney which morning and even- 

 ing they leave and return to in a body. In perching they cling to the 

 side of the chimney, using the spine-pointed tails, as Woodpeckers do, 

 for a support. The habit of frequenting chimneys is, of course, a 

 recent one, and the substitution of this modern, artificial home for 

 hollow trees, illustrates the readiness with which a bird may take ad- 

 vantage of a favoring change in its environment. 



Family Trochilid^. Hummingbirds. 



Hummingbirds are found only in the New World. About five 

 hundred species are known. They range from Alaska to Patagonia, 

 but are most numerous in the Andean regions of Colombia and Ecua- 

 dor. Seventeen species are found in the United States ; only eight of 

 these advance beyond our Mexican border States, and but one species 

 occurs east of the Mississippi. 



Several species inhabit the depths of dark tropical forests, but as 

 a rule they are found with the flowers which bloom in the clearings, 

 or far overhead in the sunlight. They are not gregarious, but an 

 abundance of food sometimes brings large numbers of them together, 

 when the air becomes animated with their rapidly moving forms. 

 The smaller species fly so swiftly that their wings are lost in hazy cir- 

 cles, and it is difficult for the human eye to follow their course. The 

 flight of the larger species is less insectlike, and each wing-beat can 

 be detected. As a rule their voice is a weak squeak or excited chip- 

 pering, but some of the tropical species have songs of decided charac- 

 ter which they sing with much energy. 



Hummingbirds feed largely on insects, which they generally cap- 



