102 MAN ON THE LANDSCAPE 



reason (including overshooting of a covey), the circle of mutual pro- 

 tection against cold is too loose to be effective. Thus, the hunter must 

 govern his take from each covey, if he wishes to hunt another year. 

 To reduce a covey below ten birds may wipe out the reserve social 

 strength needed in emergencies. 



The extinction of species such as the passenger pigeon, and the 

 heath hen shows what can happen. Long before these birds disap- 

 peared from the earth, heroic efforts were made to save them. But, 

 the damage had been done. Their biologic recuperative power fell 

 too low. Their protective reserve included number, and the necessary 

 number finally did not exist. At that point nothing could save the 

 remainder. The trumpeter swan has been hanging on just above this 

 point for several years. 



Animals whose nature is non-gregarious do not depend as much 

 upon reserves of number. Of course, they need reserves of food and 

 shelter, as do all animals. In no case can a population, whether plant 

 or animal, be maintained without a certain seed stock or breeding 

 stock. The intelligent management of this factor is complicated by the 

 cyclic rise and fall in population, particularly of wild animals. The 

 muskrat cycle may find only one-tenth as many animals at the low 

 point as at the high. Obviously, the exertion of additional pressures, 

 from human sources, at the cyclic low is dangerous to the species. 

 The regulation of duck hunting in recent years has been a matter of 

 skating as near thin ice as possible. No one knows exactly where the 

 danger point is. The only way of learning would result in extinction 

 of a species, perhaps several species. We cannot afford to find out. 

 To be safe, we must maintain ample reserves of every known factor 

 related to survival. 



Population and Resources. We cannot support ten cattle on an 

 acre of meadow for more than a few weeks at most. Following the 

 initial stage of plenty comes persistent hunger and the consumption 

 of the less palatable and ordinarily untouched plants. Then mal- 

 nourishment proceeds as the animal body consumes itself by utilizing 

 the sugars stored as starch, in fat, and in protein. Starvation ends in 

 death. 



Note that overpopulation in the animal world leads to exhaustion 

 of the plant world. When all or part of the animals have died, the 

 plant population will return in proportion to the easement of pressure. 

 Again food is available, and if there is any reproductive power left 

 in the animals their population will also rise again. 



Every breeder of animals, or plants, knows that if quality is to 

 be maintained, food and water must be ample. To supply them, man- 

 agement is essential. Competition for them must be restricted. 



In nature, competition generally favors the survival of the fittest, 

 The factors which eliminate the less fortunate are disease, accident, 

 starvation, sterility, combat. 



In addition to these, man has available several voluntary controls, 



