How to Study Birds 



THE NESTING SEASON 



BY FRANK M. CHAPMAN 

 THIRD PAPER 



The first evidence of the near approach of the nesting time among 

 birds is furnished by the phenomena of the mating season. 

 Mating Chief among these are song, and the sounds produced in 



various ways which take the place of song, display of plu- 

 mage, fighting, dancing, and the numerous peculiar evolutions through 

 which birds give vent to their feelings at this period when their physical 

 vigor is at its height. 



As a rule, these exhibitions are given only by the male; and the question 

 at issue is, are they simply expressions of the intense vitality of the season, 

 or are they designed to attract the attention of the female, and thus aid 

 the bird to win a mate? There is a wide field for study here; in fact, so 

 few really satisfactory observations on the mating habits of wild birds exist 

 that no conclusive explanations of the origin of their customs and costumes 

 have been advanced. 



Song is undoubtedly a means of announcing a bird's presence, andj it is 

 also a challenge, as well as a reply, to a rival. Nothing so stimulates song 

 as song. The crowing of cocks admirably illustrates this. While singing 

 continues after a mate has been secured, is not song ever addressed directly 

 to the female? Are there never song contests among males, with a near-by, 

 attentive female for the prize? 



In fighting for a mate, action and cause are so closely related that the 

 development of spurs, for instance, is generally attributed to that form of 

 natural selection which brings success to the strongest, best-equipped 

 fighter and enables it to transmit its own desirable characters to its of!f- 

 spring. This, however, is a matter primarily to be settled by the males. 

 Two or more males meet, battle, and the victor gets the prize of a mate; 

 but whether the mate has any voice in the matter is unknown. Conse- 

 quently, in those more peaceful forms of sexual activity when rival males 

 attempt to outdo each other through display of plumage, naturalists are not 

 agreed whether these exhibitions are designed to please the female, — who 

 presumably would then select the most attractive performer, — or whether 

 they are only a relief or outward expression to the emotions of the mating 

 season. 



Opportunities to make observations bearing on these questions are not 



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