276 BRANCH CHORDATA 



of these migrations varies. Some birds do not migrate, but 

 stay all winter in the same locality, often changing from an 

 insectivorous to a seed-eating life. Others migrate but short 

 distances. The snipes and plovers make extended migrations, 

 going from the arctic regions to the tropics, some species travel- 

 ling from Alaska to Patagonia. 



Parasitism. — The American cow-bird and European cuckoo 

 lay their eggs in the nests of other birds, where the young are 

 cared for by the foster parents, often at the loss of their own off- 

 spring. 



Rivalry among birds may be by means of ornament, color, 

 antics, battle, or song. The male is usually more brightly col- 

 ored than the female and puts on his mosi brilliant attire at the 

 courting season. Rarely the female is more brilliantly colored 

 than the male (see p. 291). In this ease she does the courting, 

 but as a rule the female is much more inconspicuously colored, 

 since she is generally the one which sits upon the nest, and it is 

 to the interest of the family that she be protectively colored. 

 Darwin believes' in the choice of the female in mating, and that 

 the attractiveness of the male may lie in the tinted or lengthened 

 beak, or the striped or brightly colored feet, or the bright wattles 

 or other appendages about the head; but the most common and 

 the most brilliant display of colors is in the plumage. Some 

 think that the health and vigor generalh" may be the cause of 

 this brilliancy, but Darwin believes that it has been intensified 

 from generation to generation by the choice of the females, thus 

 perpetuating these characteristic pleasing colors and color-pat- 

 terns in the offspring. Mr.'' ^^'allace, strangely enough, denies 

 the female any part in the matter of mating, while he ''ascribes 

 to natural selection any secondary sexual character which is of 

 practical use to the male in conflict with a rival. "^ Some birds 

 se(!m to be more easily pleased by antics and pranks which are 

 sometimes connected with the dis]ilay of ornament and some- 

 times not, as if he who made the biggest clowii of himself was the 

 favored suitor.' A familiar example of the display of beauty- 

 spots is afforded by the flicker which sits upon a twig facing his 



' Sf'c Darwin'.s " Selection in Relation to Sex," " Descent of Man." 



' Wallace's " Darwinism." 



' Baskctt, " Story of the Birds." 



