12 MAN AND ANIMALS 



crime at all, in so far as the destruction is absolutely unavoidable. The 

 wanton and useless destruction of animals not condemned as noxious by 

 years of investigation, though probably not forbidden by the example 

 of the animal world, is forbidden by the best sensibilities of every civilized 

 man and woman. When the value of an animal to us is in question, the 

 animal should have the benefit of the doubt, and we should hesitate 

 long before introducing animals of supposed value. Certainly, also, 

 every animal condemned by careful investigators should be destroyed 

 whenever opportunity is presented. Mistaken and sentimental ideas 

 cause the killing of many useful animals and the protection of many 

 noxious ones. The farmer kills snakes and skunks whenever he has the 

 opportunity, though they are among the most useful animals. Shrews 

 are master destroyers of mice. Still many people mistake shrews for 

 meadow mice and destroy them. Likewise the housewife kills the 

 house centipede, the enemy of household pests, as a dangerous and 

 repulsive creature even in the absence of any knowledge of the question- 

 able charge that it bites young infants. Mistakes are not confined wholly 

 to uninitiated individuals. Misjudgment by the officials of the Brook- 

 lyn Institute of Arts and Sciences, possibly influenced by the sentiment 

 of Longfellow's mistaken poem on the " Birds of Killingworth " brought 

 about one of the first official introductions of the English sparrow. Thus 

 we see that the complexity of the problem demands careful study and 

 conservative action. 



2. MAN-MADE COMMUNITIES 



Animal communities are divisible into primeval or primary com- 

 munities, and man-made, or secondary communities (12, 13). As has 

 been noted when civilized man enters a new territory, he first destroys 

 all large game which threatens himself and his domestic animals. He 

 then destroys the natural vegetation and other animals by clearing the 

 timber, burning all woody debris, and plowing and putting out plants 

 which are entirely new to the region. Under primeval conditions, 

 plants are arranged irregularly, as roughly indicated by the letters in 

 Diagram 1 ; after being put to agricultural purposes, they are arranged as 

 in Diagram 2. The plants are all of one kind and are arranged in rows. 

 A grove of the original vegetation is sometimes left. The rate at 

 which these changes take place is directly related to the rate at which 

 man occupies and cultivates the new territory. As compared with 

 natural changes, this process is rapid and is accompanied by an equally 

 rapid decline of primeval or primary communities. 



