fequiTemelits to Oause no fear of competition. In this way, al- 

 though a given area may appear to be indiscriminately occupied by 

 many different kinds of birds, it is in reality more or less definitely 

 divided into territories with fairly definite boundaries between pairs 

 of individuals of each species. Naturally the boundaries do not coin- 

 cide for the different species. Among the passerine birds the sing- 

 ing of the male of a pair is not merely an expression of happiness 

 but is also a warning or notice to others of his kind that the terri- 

 tory in which he is singing is his own and that none should tres- 

 pass on it. In the case of sea birds that nest in colonies but obtain 

 their food from the ocean, the only territorial requirements of a 

 nesting pair is that there be enough room for the adults and their 

 nest. On the nesting site conflicts do not arise over food, because 

 this is obtained in the ocean at a distance from the shore. 



When certain mammals have established themselves on a given 

 territory others appear to recognize, to some extent at least, the 

 accompanying property right. We sometimes, for instance, see a 

 small dog drive a larger, more powerful dog off the smaller dog's 

 territory or away from its bone. Incidents of this kind can regu- 

 larly be seen among other animals such as wolves, coyotes, foxes, 

 squirrels, chipmunks, ground squirrels, and others. 



VOICE AND COMMUNICATION 



I have yet to become acquainted with an animal to which I feel 

 that the term "dumb animal" should be applied. Animals are cer- 

 tainly not dumb as far as communication among themselves is con- 

 cerned, and they must be fairly intelligent to have survived through 

 the ages until man, the most dangerous and destructive of all crea- 

 tures, began to kill them wantonly. 



We are, of course, well acquainted with the voices of domestic 

 dogs, cats, horses, cows, and other animals; but many creatures that 

 are generally considered to be dumb actually have voices and use them 

 regularly in communicating with their own kind. 



"Bobbity," a tiny pocket mouse that lived on my desk at home for 

 several years, appeared to be entirely silent. However, when I held 

 him practically against my ear I found that he was carrying on a 

 rapid chattering and scolding. Perhaps he understood my language 

 and I was the dumb one because I did not understand his. A little 

 female of the same species that was a temperamental spinster, had 

 but to look at "Bobbity," change her expression ever so little, and he 

 would be almost cowed. I am satisfied that she talked to him most 

 effectively. 



Kangaroo rats generally appear to be silent; but I have noticed 

 tliat when two are brought together and do not desire to tolerate 



