58 THE WORLD'S BIRDS. 



DISTRIBUTION AND IMPORTANT SPECIES. Birds of this 

 family, which contains about a hundred species, 

 are found all over the world, but chiefly in hot 

 climates, always, of course, near water, usually 

 fresh rather than salt. Our common British 

 species (Ardea cinerea] is widely distributed over 

 the Old World ; in America the very similar 

 Ardea herodias (Great Blue Heron) is common ; 

 this has cinnamon markings on the wing-edges and 

 thighs. In America the Little Green Bittern 

 (Butorides virescens), about as big as a jackdaw, 

 and dark-green and grey, is well known. In India 

 the most familiar is the pied drab-and-white 

 Paddy-bird, or Pond Heron (Ardeola grayii), 

 about the size of the last. 



HOATZIN (Opisthocomidcz). 



DIAGNOSIS. A tree bird, with short stout bill, long tail, 

 and four well-developed toes, the hinder one smallest, 

 and none connected by webs. 



SIZE. About that of a pheasant. 



FORM. Bill short, stout ; corner of mouth below fore- 

 head ; feet with shanks of moderate length, toes 

 four, first one directed backwards, front ones not 

 united at base ; wings broad, but short ; tail long 

 and rounded ; head small, crested. 



PLUMAGE AND COLOURATION. Feathering coarse in 

 texture ; no sex-difference or seasonal change ; 

 young resembling adult ; head with a full crest 

 of narrow feathers. Face bare. 



YOUNG. Clothed at first with scanty hair-like down, 

 then with a thicker fawn coat ; active climbers, and 

 able to swim and dive on occasion ; in climbing they 

 use not only the bill and feet, but the wings, which 

 have well-developed claws on the two first fingers 



