THE WORLD'S BIRDS. 159 



Captivity. — They have done well in the London 

 Zoological Gardens, and reared young there. 



Distribution and Principal Species. — ^Two species 

 only [Eurypyga helias and E. major) are known, 

 much like each other, inhabiting South America 

 and living by the waterside in wooded places. 



Swifts {Cypselidce), 



Diagnosis. — Swallow-like birds, with the first toe the 

 smallest, and only ten tail-feathers {as against twelve 

 in swallows). 



Size. — From that of a blackbird to that of a tit 

 (allowing for shape). 



Form. — Much as in swallows, with small bill and feet 

 and long wings. Bill with corner of mouth coming 

 below eye ; feet with very short shanks, usually 

 feathered, and never scaled, first toe smallest and 

 often directed inwards and forwards instead of 

 backwards ; wings very long ; tail long or short, 

 forked, square or rounded ; in latter case often 

 with spinous tips to quills. 



Plumage and Colouration. — Black and white com- 

 monly, but sometimes showing brown or metallic 

 blue and green ; usually no sex-difference, and no 

 seasonal change. Fledged young much like adults, 

 but with light edgings to the feathers. 



Young. — Naked and helpless, fed by parents. 



Eggs. — One to four ; pure white, elongated in form; 



Nest. — Various, usually on rocks or buildings, some- 

 times on trees ; made more or less of the birds' 

 sticky saliva. 



Incubation. — Eighteen days. 



Food. — Insects, usually captured on the wing. (I 

 have, however, once seen a Collocalia picking in- 

 sects off a tree as it swept past.) 



Gait. — An awkward crawling walk ; they are planti- 



