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to some thicket; any unusual sound causes the sharp 

 eyes to seek its source. Raptorial birds, weasels, snakes 

 and other animals catch robins when they can, and are 

 particularly likely to prey upon young individuals. In a 

 general way the coloration of a robin protects it from such 

 sharp-eyed enemies. The body is countershaded (dark 

 above and light below) so that it is not conspicuous when 

 illuminated from above, because the lighter parts are in 

 the deepest shadow. The pigments in the feathers also 

 blend well with the tree trunks and branches which robins 

 usually frequent. When a robin is alarmed or threatened 

 with danger it gives certain call -notes which warn its 

 fellows of the trouble, so that they may either look out 

 for themselves or come to investigate the cause of the 

 disturbance. 



A robin is much better equipped than a lizard to meet 

 the varying conditions of a terrestrial environment. Both 

 have a dry skin which conserves the water within the 

 body, but feathers are better than scales because they 

 keep a layer of air next to the body which serves as an 

 insulator against loss of moisture by evaporation or of heat 

 by radiation. A bird is also more specialized than a lizard 

 in having a constant body temperature which is main- 

 tained in spite of biting cold or extreme heat. Most robins 

 migrate southward to pass the winter in a warm climate 

 where food is abundant, but a few may linger in certain 

 northern localities until spring. The migration of the 

 robin covers a distance of approximately 3000 miles. In 

 autumn the trip takes about eighty days, and in spring, 

 seventy. The birds move northward as the mean daily 

 temperature reaches 35F. 



Birds are subject to attack by various diseases. A robin 

 may acquire bird malaria from the bites of mosquitoes, 

 and certain bacteria may cause internal disorders. Trema- 

 todes and other worms live within the body; bird lice and 

 other ectoparasites dwell among the feathers. Such dis- 

 eases and parasites the robin avoids as far as possible by 



