THE WORLD'S BIRDS. 65 



HuMMiNG-BiRDS [TrochilidcB), 



Diagnosis. — Very small perching birds , with slender 

 hills and very short shanks. 



Size. — From that of a swallow to that of a large humble- 

 bee. Some are the smallest of known birds. 



Form. — Bill always slender — medium, long, or very 

 long, usually straight ; feet with very short shanks 

 and four free toes, three in front and one behind ; 

 wings narrow and generally long, with the arm 

 bones very short, most of the length being due to 

 the primary quills ; tail very varied in form ; head 

 large, neck long, body small but plump. 



Head and foot of Giant Humming-Bird {Patagonia gigas). 



Plumage and Colouration. — Feathering close and 

 usually metallic, very commonly coloured green, 

 the lustre often very intense ; no seasonal change, 

 but often a sexual difference. Young like the female; 



Young. — Naked and helpless, with the bill short and 

 broad at first. 



Eggs. — ^Two ; pure white. 



Incubation. — Ten days, the hen only sitting. 



Courtship. — The male plays on the wing with expanded 

 tail. 



Nest. — Suspended from a leaf or branch, to which it 

 is fastened by one side ; very neatly made of 

 plant-down, spiders' webs, etc., and small even for 

 the size of the birds. 



Food. — Minute insects, etc., and nectar obtained from 



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