° 1914 j Strong, Habits of the Herring Gull. 193 



indicate resourcefulness or adaptiveness may be only variations in 

 stereotyped behavior. 



It is to be expected that so-called pure lines or strains may be 

 found among the behavior characteristics of a species as well as in 

 other characters. Some of these strains may possibly be the result 

 of or be accentuated by such segregation as is afforded by separate 

 breeding places. Unfortunately we know nothing concerning the 

 relationships of individuals in one colony to those of another. We 

 have no information concerning whether gulls breeding at one of the 

 Strawberry Islands, for instance, have interbred in recent years 

 with Gravel Island gulls. Furthermore, we have no data as yet, 

 concerning the existence of defuiable pure lines in the morphologi- 

 cal characters of Herring Gulls. 



The other type of variability in behavior is not associated with 

 pure line inheritance. It represents simple chance variations from 

 the average type of behavior which are to be expected just as we 

 find variations in morphological characters. 



In the section of this paper which deals with the general behavior 

 of Juvenal gulls, I mentioned variability in the behavior of some 

 newly hatched gulls. A single bird in one nest showed no terror, 

 whereas two nestlings of essentially the same age in another nest 

 were in great distress from fright over the presence of human 

 intruders. I can think of no reason for considering that either 

 the quiet bird or the frantic pair were more intelligent or that 

 either form of behavior was adaptive. Nor have we reason to 

 believe that it was a case of pure line differentiation. It seems 

 quite possible that chance variations in the metabolic states of the 

 birds or possibly in their nervous organization were responsible 

 for the difference in reaction to our presence. It is conceivable 

 that the reactions would have been either similar or reversed if 

 we had approached the nests a few hours later. 



A large amount of variation has been noted in the choice of 

 materials used in constructing the nest. Evidently the Herring 

 Gull uses what is available with a preference for finer and softer 

 materials. It seems probable to me that such nest building, which 

 is evidently mostly instinctive or stereotyped, is not absolutely 

 without the elements of intelligence. There must be adaptation 

 of special materials which may be found, to use and location. 



