A major reason for conflict in the animal world is territory. The male animal (21) an area. The size of the area is sufficient to provide food for him, his (22) and their offspring. Migrating birds, for example, divide up the best territory in the order of "first come, first (23) " The late arrivals may acquire (24) territories, but less food is (25) , or they are too close to the (26) of the enemies of the species. When there is conflict over territory, animals will commonly use force, or a (27) of force, to decide which will stay and which will go. It is interesting to note, however, that animals seem to use only the (28) amount of force necessary to drive away the intruder. There is usually no killing. In the (29) of those animals which are capable of doing each other harm, there is a (30) for the losing animal to show the (31) animal that he wishes to submit. When he shows this, the (32) normally stops fighting. Animals (especially birds), which can easily escape from conflict seem to have no (33) against killing, and equally no (34) for (35) . The losing bird simply flies away. However, if two doves age (36) in a cage, and they start fighting, they will (37) to fight until one kills the other. We all think of the dove (38) a (39) of peace and, in its natural habitat, it is peaceful. But the "peace" mechanism does not (40) in a cage.