44 Studies in Animal Behavior 



dispersed far and wide, and parental solicitude, hav- 

 ing subserved its purpose of affording protection 

 when it was most needed, is manifested no more. 



When care becomes extended from the eggs to the 

 young a course of development is begun in which 

 relatively more and more care is bestowed upon the 

 offspring as we pass to higher forms. Instead of a 

 large number of progeny left to shift for themselves 

 with a consequent great loss of life, we find in the 

 higher animals a decrease in the number of offspring 

 combined with an increase in the care and attention 

 devoted to each. The young become at the same 

 time less able to take care of themselves and are de- 

 pendent upon their parents for longer periods. And 

 along with these changes there is an increase of sym- 

 pathy, affection and the various emotions that come 

 into play in the family relation. 



This is well shown among the birds. The lower 

 birds lay many eggs either in crude nests or none. 

 The young birds which are quite active when hatched 

 do not remain long under their parents' care, and 

 many are lost. The higher song birds, on the other 

 hand, lay few eggs in a well-prepared nest, and the 

 young which remain in a weak and helpless state for 

 a considerable time after hatching are fed by their 

 parents, kept clean, and protected from various ene- 

 mies. There are few more fascinating pictures of 

 domestic life than those afforded by the little family 

 group in many of the higher birds. 



Among the mammals we may trace a similar line 



