BROOD-CARE IN BIRDS 149 



of the parental care which otherwise they would have enjoyed. 

 The common cuckoo and some other cuckoos carry this 

 parasitic habit further. The eggs are always deposited by the 

 female in the nests of other birds, and the young cuckoo, when 

 it is hatched, creeps under the nestlings of its foster-parents 

 and by a violent effort raises them one by one on its hollow back 

 and jerks them out of the nests, so securing undivided attention 

 in future. 



Some birds are content with very little preparation for the eggs, 

 whilst in others the most elaborately constructed nests are prepared. 

 The New Zealand kakapo or ground-parrot hides in holes and burrows 

 and lays its eggs there without any preparation. Ostriches have 

 the reptilian habit of digging a hole in the ground, in making 

 which several females combine, and then deposit the eggs and 

 cover them up. Emus scrape a shallow hole in the ground 

 and do not cover the eggs. The cassowary scrapes together a 

 rude pile of leaves and mould on which she lays the eggs. The 

 apteryx lays a single enormous egg, which she hides among fern 

 roots. Most of the auks lay their single egg on a bare ledge of rock, 

 making no preparation for it. Penguins may lay on the bare rock 

 in the huge communal rookeries or breeding-grounds which they 

 frequent, or may scrape together a rude heap of debris. The 

 stone-curlew and the goat-sucker choose a site carefully, returning 

 to it year after year, but make no preparation, laying the egg on 

 the bare ground. Birds belonging to many different groups choose 

 natural cavities, burrows, caves, or hollow trees for their eggs, and 

 may either line these with leaves, feathers and other soft materials, 

 or make no further preparation. Not infrequently they use their 

 feet to enlarge the burrows, or even to dig them out. Puffins, 

 for instance, regularly breed in rabbits burrows, sometimes 

 turning out the rabbits, but enlarge them or make shift to 

 dig holes for themselves. Most of the petrels and a few ducks 

 breed in burrows. The stockdove and the rockdove breed in 

 caVes, in clefts in the rock, or in holes in trees. Most of the 

 parrots, as well as kingfishers, hoopoos, owls and woodpeckers, 

 hombills and sand-martins, dig out holes in wood or sand, or occupy 

 holes already made. 



Most of the game-birds, shore-birds, waders, and ducks and 

 geese lay on the ground or in low-l5dng situations, and show every 

 transition from a mere scraping on the rocky shore to an elaborate 

 collection of twigs, leaves, plant refuse of all kinds, making heaps 



