ANIMAL BEHAVIOR—ERNEST P. WALKER 275 
supply are not destroyed. We can see numerous examples of animals 
that have gone ahead fairly successfully with their ives when man 
has not interfered too much with conditions essential for them to live. 
Another group consists of animals that thrive in close proximity to 
man and either become a part of man’s household and receive his 
direct aid in their existence, or adapt themselves to the conditions 
that man provides and obtain food and shelter in spite of his utmost 
efforts to control them. In this group are the Old World rats (Rattus) 
and mice (Mus) that have become established almost throughout the 
world wherever man has made settlements. Other examples are the 
European house sparrow (Passer domesticus), commonly called English 
sparrow in the United States, and the European starling (Sturnus 
vulgaris) both of which have become firmly and widely established in 
North America. These two birds, like the rats and mice, have be- 
come pests in some regions where they have adapted themselves to a 
remarkable degree and have become very plentiful. They have found 
sufficient food and shelter around man’s activities so that they have 
thrived where other less adaptable forms have not been able to sur- 
vive. Indeed, in many cases they fight the native birds and take 
over the ecological niches normally occupied by the local birds that 
are less adaptable and aggressive and have not been successful in 
defending their territory. 
It is sometimes said that there is a third group of animals comprising 
those that cannot tolerate proximity to man but, if we study the 
problem, we usually find that man’s activities so changed conditions 
essential to them for food or shelter that they could not survive, or 
else that man intentionally killed them off. 
Most animals, if given to understand that man will not harm them, 
will become tame, and if man will feed them it is surprising how 
friendly even very wild kinds will become. I have a pet big brown 
bat (Eptesicus fuscus) that in a few days became so tame it would 
return to me after each of its flights about the room (pl. 13, fig. 2). 
Even when I awaken her she makes some effort to overcome her 
stupor and come into my hand to be warmed preliminary to taking 
her evening flights and receiving mealworms, of which she is very 
fond? 
Chipmunks (Zamias) that have been tame during the summer or 
fall, then go into partial or complete hibernation and are inactive 
for a period of from 5 to 6 months, come out in the springtime and 
resume their friendships and friendliness practically as though they 
have not been interrupted. One individual that came in the window 
onto my desk and was so tame that I took a picture of it while it was 
on my hand obtaining food, returned the following spring and re- 
7 fa the Saturday Evening Post for February 4, 1950, is an account of further results of my studies of 
ats. 
