GONADAL HORMONES AND SOCIAL BEHAVIOR 



124: 



males ranking lowest in the peck-order 

 among the cocks may show varying degrees 

 of suppression of sexual behavior to the 

 point of psychologic castration (Guhl, Col- 

 lias and Allee, 1945; Guhl and Warren, 

 1946). One male failed to mate with the 

 hens of the flock even when his social 

 superiors were temporarily removed, but 

 he did mate with strange hens from another 

 flock. Similar situations have been reported 

 by Darling (1952j among wild white cattle 

 of Northumberland, England, and water 

 buffalo of southeast Asia. It is pertinent 

 to the point being discussed that the domi- 

 nant bull water buffalo must have two other 

 bulls to dominate before he is potent. 



The habits associated with the inde- 

 pendence of action at top levels in a peck- 

 order may suppress receptivity in females of 

 some species. Hens at upper ranks in the 

 flock tended to be least receptive and those 

 at the lowest levels the most receptive. The 

 females at the top of the hierarchy were in 

 the habit of dominating, whereas those at 

 the bottom submitted readily. The sub- 

 missive attitude is a component of recep- 

 tivity. When the degree of domination or 

 submissiveness was altered by subflocking, 

 the differences in the rates of displaying the 

 submissive sexual crouch were reversed 

 (Guhl, 1950). With fewer birds to domi- 

 nate there was less reinforcement of the 

 aggressive habit and the sexual crouch was 

 evoked. Similar tests with other species of 

 vertebrates should be made to determine 

 the extent to which this psychologic effect 

 is applicable. Relationships between physio- 

 logic and psychologic aspects of display 

 behavior in birds have been discussed by 

 Armstrong (1947, Ch. 22). He states that 

 the interconnection of internal and en- 

 vironmental factors has the broad effect 

 of bringing the birds into breeding con- 

 dition, and the fine adjustments which 

 achieve the final sexual synchronization 

 are given by psychologic factors. 



D. SOCIAL INERTIA AND THE DEVELOPMENT 

 OF SOCIAL BEHAVIOR 



To answer the second part of the question, 

 social inertia is also important for the de- 

 velopment of social behavior. Chicks reared 

 in groups established certain behavior pat- 



terns in relation to each other (Guhl, 1958), 

 the social inertia mentioned above, and re- 

 quired 8 to 13 weeks to develop a new 

 peck-order. Similar chicks reared in partial 

 isolation and assembled at 8 to 10 weeks of 

 age were devoid of such habits. They en- 

 gaged in fighting and pecking, and formed 

 peck-orders in a matter of hours. Chicks 

 treated with an androgen while reared to- 

 gether established peck-orders somewhat 

 earlier than normal group-reared chicks. 



Another experiment was devised to com- 

 pare the effects of androgen with those of 

 social inertia. The specific question was 

 whether chicks treated with androgen dur- 

 ing partial isolation from hatching would 

 form a i^eck-order earlier than treated 

 chicks reared as a group. There were 5 

 groups of chicks (Fig. 20.2). Two groups of 

 11 each were pen-reared controls; the in- 

 dividuals of one group received 0.5 mg. tes- 

 tosterone propionate daily, those in the 

 other group were normal controls. Three 

 groups composed of 10 chicks each were 

 reared in partial isolation and treated with 

 the androgen. One was assembled when 31 

 days old, another at 41 days, and the third 

 when 51 days old. The establishment of 

 dominance relationships (peck-rights) was 

 observed for 56 days in the pen-reared 

 groups and for 7 days after assembly in the 

 case of the 3 isolation-reared groups. 



The results are shown in Figure 20.2. The 

 ratios at each curve indicate the number of 

 peck-rights established at that point in re- 

 lation to the possible number of unidirec- 

 tional dominance relations in the flock. 

 The group assembled on day 31 nearly com- 

 pleted a peck-order in 1 week, and ex- 

 ceeded the treated males reared as a group. 

 The treated chicks assembled on day 41 

 failed to establish any dominance relations 

 on the first day and formed only 20 out of 

 a possible 45 pecking relationships by the 

 end of a week. This performance was in- 

 ferior to the normal pen-reared controls. 

 The results with the group assembled on day 

 31 indicate that in the absence of social 

 inertia, androgen treatment resulted in some 

 precociousness of agonistic behavior. 



The results obtained from the males as- 

 sembled on day 41 are difficult to explain. 

 In nature behavior j^atterns tend to appear 



