SOCIAL LIFE OF ANIMALS 485 



Men are not sheep, but they have two of the dominating characteris- 

 tics of sheep. They are gregarious and they are easily frightened. 



— Ramsay MacDonald. 



Polygyny (many wives), and Polyandry (many husbands). — In 

 the ostrich of South America the cock bird lives with five or six 

 hens {polygyny). All the hens lay their eggs in one nest, but incu- 

 bation is done by the male alone, and after hatching, the young 

 chicks follow the father. Each female cowbird mates with several 

 males {polyandry). The female deposits her eggs in the nest of 

 another smaller species. (See p. 349.) 



Cases in Which the Sexes Live Apart. — In the case of many 

 antelopes the herds divide according to sex between one pairing 

 time and another. After the pairing season is over, wild sheep and 

 other ungulates live in herds composed of one sex only. In Indian 

 and African elephants the sexes form herds of their own, herds of 

 females being accompanied by their young and led by a female. 

 At breeding time a male temporarily takes possession of a herd of 

 females. Migrating salmon travel separately, shoals of males 

 appearing first, followed later by the females. The same is true with 

 the salt-water minnow {Fundulus heteroclitus). 



Societies Composed of Different Species. — Different species of 

 dolphins form groups led by one individual. Wild zebras, asses, 

 yaks, and horses are sometimes seen together, while wild buffaloes 

 associate with elephants. 



Monogamy. — All species of parrots are monogamous, while 

 rose-colored starlings, sparrows, house pigeons and mallards are 

 monogamous, but nest gregariously. In the weaver bird two cou- 

 ples often share a common nest in which both the hen birds lay their 

 eggs and hatch them out. 



Seasonal Mateships. — Seasonal mating occurs in a number of 

 beetles, the couples living in associations, not societies. Lions 

 choose a fresh mate at each pairing time while in some marten species 

 the two sexes live together until afteriUjg young have been reared. 

 Foxes live monogamously and the father brings food to the young. 

 Wolves, foxes, and bears live mated for a short time. 



Types of Families, (i) Parent Families. — In the wood-boring 

 beetles, the parents feed the larvae and watch over the chrysalis. 

 Both the male and the female of certain species of fishes guard the 

 nest, the hatched young returning to the nest every evening for two 



