CHAPTER X 



BROOD-CARE IN BIRDS 



All birds lay eggs protected by a hard shell and containing a 

 quantity of yolk for the nutrition of the embryo. The greater part 

 of the development takes place after the egg has been laid, and is as 

 direct as possible, ancestral larval stages having been suppressed. 

 The eggs themselves and the young chicks are a tasty and nutritious 

 prey for many kinds of animals. Some lizards and many snakes 

 are eaters of eggs, whilst young birds are even more favourite 

 victims. These reptiles are keen-sighted, active and lively, and 

 hunt over the ground, searching the best-concealed crannies, 

 penetrating dense thickets and climbing the tallest trees. Nor do 

 birds themselves respect their own kind. In almost every family 

 there are some which will prey on the eggs and young of other 

 birds. Gulls, magpies, ravens, carrion crows, moorhens and brush 

 turkeys are notorious robbers, and will go long distances to ferret 

 out nests and young. Mammals of all kinds are even more serious 

 enemies, and not a few that are usually vegetarian often devour 

 eggs. Rodents, for instance, are habitually feeders on grain, roots, 

 leaves and other vegetable matter. But rats are clever and 

 persistent thieves of eggs, especially of those that are to be found on 

 the ground or in holes, whilst many will ascend bushes or tree 

 stumps in pursuit of their prey. Squirrels have a still greater 

 range of destructiveness, as they will hunt on the ground as well as 

 on the trees, and although for the greater part of the year they 

 are purely vegetarian, in spring they plunder nests. The Zoological 

 Society of London introduced American grey squirrels into Regent's 

 Park, and although these have been a delight to the people of London 

 and have added greatly to the pleasure of visitors, it is probable 

 that they have seriously diminished the bird population. Wood- 

 pigeons, thrushes and blackbirds and all the small songsters that 

 build in shrubs and hedges have had their nests pulled to pieces 

 and their eggs and young destroyed. The smaller tree-chmbing 

 carnivores, although many of them are vegetarian and frugivorous, 



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