Size
Size is the most obvious characteristic possessed by an animal. Whether we are naturalists or sportsmen, or neither, we instinctively classify all animals as large or small. Likewise there is nothing about our fauna so obvious as the fact that the larger animals are disappearing. The bison is gone, except for a few small and protected herds. The elk, moose, caribou, mountain sheep, antelope, cougar and grizzly and black bears are gone, except in sparsely settled regions. On the other hand, rodent pests swarm throughout every city, and the field mice, ground squirrels, cabbage butterflies, house-flies and hosts of other small insects continue to make trouble for the agriculturist.
Large size increases the value of an animal whose products are useful and hence makes it more desirable game for the pioneer who hunts to supply his larder and also for the sportsman who hunts for the sake of trophies. Large size also makes an animal apparently more dangerous if it has rapacious habits. I say apparently, for the microscopic bacillus tuberculosis kills more people in North America every year than all the beasts of prey have killed on the same continent since Columbus first sighted San Salvador, while the house-fly, disseminating the germs of typhoid fever and kindred diseases, is more deadly than all the wolves, panthers and rattlesnakes.
Sometimes we find related species having the same habits and living in the same region, but differing in size. Invariably the larger species is more sought after and diminishes more rapidly than the smaller. Squirrels illustrate this statement very well. In the northeastern United States three species of tree squirrels were once abundant. All had very similar habits, and ate practically the same kind of food. The fox squirrel and the gray squirrel are now on the verge of extinction in many places, while their smaller relative, the little red squirrel, thrives. Likewise the coyote fares better in contact with civilization than does the wolf, and the cottontail rabbits thrive where the larger jack rabbits and snowshoe hares are being exterminated.
Eight species of woodpeckers were once abundant in the forests all over the eastern states. Six of these are still common while the two largest species are extinct except in a few inaccessible swamps.
Large size means great strength. In the past this has been an advantage, within certain limits, by making an animal invincible to the attack of other animals. It is of no avail in stopping bullets, and hence is a disadvantage to a species that must count civilized man as one of its enemies.
The animals of the future, not only in North America but the world over, will have a smaller average size, and most large species-will cease to exist unless they are domesticated.
