THE PRINCIPAL BIRD GROUPS 95 



readily distinguished from all other avine forms 

 by their characteristic beak and zygodactylous 

 feet. The former is in most species short and 

 strong and arched, the upper mandible mobile 

 and loosely articulated to the skull, the lower 

 mandible truncated: the base of the bill is 

 furnished with a cere. The Parrots (numbering 

 about five hundred species) may be divided into 

 half-a-dozen fairly well defined families as 

 follows : the Stringopidae or Owl Parrots, of 

 which but a single species is known ; the Psitta- 

 cidae or Typical Parrots ; the Cacatuidae or 

 Cockatoos ; the Cyclopsittacidae ; the Loriidae or 

 Lories ; and the Nestoridae or Keas. The Owl 

 Parrot or Kakapo (Stringops habroptilus) is 

 apparently unable to fly, spending its time upon 

 the ground or climbing about the trees, balanc- 

 ing itself with its short rounded wings. Other- 

 wise the wings in this order are fairly long and 

 powerful ; the tail varies considerably in shape, 

 short and square, elongated, wedge-shaped, and 

 in some species the central feathers are bare of 

 barbs except at the tips, where they form 

 racquets. In this order the colours are often 

 gaudy, and displayed in the loudest of patterns. 

 Parrots are of gregarious habits. Their food 

 consists principally of nuts, fruits, buds, leaves, 



