PSYCHOLOGY AND BEHAVIOR 65 



the object of attack by most other birds in the enclosure. If, on the other hand, the combat 

 ends in the weaker bird edging away without being pursued, meanwhile recognizing the victor 

 as the dominant individual, it may in turn be successful in combats with others, thus estab- 

 lishing its own position without serious harm to itself. 



Although the order is not directly determined by sex or age, the fact that the heavier and 

 larger birds are principally males over one year old usually results in a larger proportion of 

 these birds occupying high ranking positions of dominance when groups comprising all ages 

 and sexes are penned together. Since those low in the scale must keep out of the way of their 

 stronger companions, the practice of segregating males from females and, occasionally, adults 

 from birds of the year, has grown up. Even in such groups, however, a dominance order 

 soon develops. 



It is interesting to note that, should a dominant bird in one pen be placed in another, it 

 must establish its rank among its new companions by the same method as heretofore 

 described. In this case, however, the new arrival is at an added disadvantage in that the 

 resident birds have also established a feeling of ownership of the territory represented by the 

 pen. Apparently the newcomer recognizes this and is, therefore, placed at a psychological 

 disadvantage at the start. It is for much the same reason that a bird once removed from an 

 enclosure and later returned thereto, does not always reestablish its old position in the social 

 scale. Also, if a vigorous bird, high in the social order, is weakened by disease or some other 

 factor, it will be forced by its companions to assume a lower position in the hierarchy. It is 

 such considerations as these that have given rise to the practice of shifting a bird in captivity 

 from one pen to another when it becomes so strongly dominant as to upset the social balance 

 of the pen. 



Translated in terms of relationships among wild grouse, it is possible that the existence of a 

 strong dominance complex, particularly among the males, represents one of the important 

 factors limiting the numbers which will occupy a given habitat. One likewise finds here a 

 possible explanation for the breakup of a brood in the fall for, at least in captivity, the 

 young birds, as early as the first half of September, begin the conflicts that lead to the 

 establishment of a social order. 



Mating Behavior 



Aside from dominance, the only other behavior pattern which is sufiBciently distinctive to 

 warrant special consideration outside of the chapter on General Habits, occurs during the 

 mating period in response to the marked physiological and psychological changes associated 

 with the reproductive cycle. Here, too, one must turn largely to observations on captive 

 grouse for a knowledge of reactions and an interpretation of their meaning. 



Watching grouse activities throughout the spring and early summer, one is impressed by 

 the number and variety of reactions to be obser\'ed. With close study, however, they will 

 be found to fall logically into three phases as here described. 



Strutting Phase 



In the pens at the Research Center, where males and females are by necessity placed together 

 most of the year, the males show signs of aggressiveness towards their penmates of either 

 sex as early as the first of March. Though they may have been strutting* on warm days 

 throughout the winter, they now display more frequently and with greater vigor, even in the 



* See Chapter V, p. 282. 



