280 FIELD ZOOLOGY. 



round of his own steps. Let him pass from the streets of 

 a town into a pathless field, and he will be quite likely to 

 lose his way unless he sees some objective point and keeps 

 it in view. He seems not to possess now, if he ever did 

 possess, any inherent sense of direction with respect to 

 himself. This sense of direction is possessed by many of 

 the lower animals, and by some of them in a marvelous 

 degree. 



The Nesting Season. 



Spring in every clime is the nesting season for birds. 

 This does not mean April or May the world round. On 

 the other side of the equator, it is September and October. 

 Spring, with migratory birds, means the season of plant 

 growth in their nesting homes. In the tropics, although it 

 is warm the year round, the nesting season is as well 

 defined as it is in more northern climes; there it occurs 

 with the return of the tropical rainy season, the time 

 when fruits and seeds are abundant, and insects are abroad 

 in search of either or both. Among temperate latitude 

 birds, the birds whose young are fed on flesh are the first 

 birds to nest, while fruit- and insect-eaters nest later. In 

 the middle latitudes, the domestic pigeon may nest 

 earlier than even the flesh-eating birds; occasionally 

 young broods are heard in January, if the winter is an 

 open winter. 



In the choice of a mate, birds display traits surpris- 

 ingly, sometimes mortifyingly, human. The believer 

 in the theory of natural selection will find abundant 

 material for study if he will observe birds during the 

 mating season. For any given season, the rule for the 

 union of birds is monogamy, and polygamy is the excep- 

 tion; and so far as present knowledge goes, the choice of 



