198 TEXT-BOOK OF ZOOLOGY 



pigeon insures itself against the attack of martens and other mammalian 

 beasts of prey. The tame pigeon also selects for its nesting quarters 

 places of similar character (such as towers, pigeon-houses supported on 

 pillars, boxes fixed against a wall, etc.). Like its ancestral parent, it 

 never, or only exceptionally, settles upon trees. 



D. The Young Birds. 



1. Like all cave-breeders, the pigeon builds a rough nest out of straw 

 and a few feathers, for, being sufficiently protected by its hiding-place, 

 the bird does not need a structure artistically contrived to resemble its 

 surroundings. (Compare, on the other hand, nightingale and chaffinch.) 

 For the same reason, also, 



2. The eggs are without protective colouring (see chaffinch), but are 

 pure white (see owl). The bird produces annually from three to six 

 clutches of two eggs each, which are incubated by the male and female 

 alternately. 



3. The young are at their birth blind, and quite helpless (aves 

 altrices). As they leave the egg completely naked, they have to be 

 warmed by the parent birds. Neither are they able at this stage to 

 digest the hard granular food. Accordingly, for about the first twenty 

 days of their existence they are fed upon a fatty, crumbly substance 

 formed at this period in the crop of the parents (so called pigeons' milk). 

 Afterwards they are fed with grain which has been softened in the crop 

 of the parents. 



4. The young are reared with great difficulty during the first days of 

 their life, much more so than is the case with other birds. This accounts 

 for the pigeons only laying a few eggs at a time, for it would not be able 

 to rear more than two young birds. 



5. The support and nourishment of the young, even during a later 

 period, entails much trouble and labour for the parent birds. Hence, 

 like all birds the young of which are reared in the nest, pigeons are 

 monogamous in their sexual relations. (Compare, on the other hand, 

 the domestic fowl.) On account of the tender affection which the pair 

 show for one another, the dove has been for ages the symbol of love. 



Allied Species. 



The Ring-Dove or Wood-Pigeon (Palwmhts torqnatus) is a familiar 

 inhabitant of our woods. It prefers pine and fir woods, its food con- 

 sisting chiefly of the seeds of coniferous trees. The nest is a simple 

 structure, which it builds in the dense branches of bushes and young 

 trees. The plumage is blue-grey, with a white spot on each side of the 

 neck (hence name ring-dove). 



