ANIMAL AGGREGATIONS 



415 



tense body and erect fins; the fish seems 

 to hang limply in the water; it backs slowly 

 away and then turns and flees. Many ani- 

 mals, among them hens, mice, and boys, 

 not infrequently emit characteristic cries 

 when beaten. The head furnishings of de- 

 feated hens sometimes blanch, while those 

 of the victor remain flushed. Defeated mice 

 rear up in characteristic postures. 



Other signs of low social rank include 

 the avoidance of encounters with superiors; 

 defeated hens move about quietly, often 

 with head held low, or hide in out-of-the- 

 way places or in protected niches. Animals 

 of low rank sometimes accept or even offer 

 to assume, the female position in a copula- 

 tion; monkeys and cats have this tendency. 



LEADERSHIP 



In the best sense, leadership consists in 

 giving guidance by going before and draw- 

 ing others along the same course or pat- 

 tern of behavior. A leader is often able to 

 attract others to follow, but sometimes 

 compulsion is relied upon to control and 

 even to secure followers. The leader of a 

 group of animals may be young, mature, 

 or old, and of either sex; often the fol- 

 lowers vary similarly. The leader may be 

 one individual, or there may be a group 

 of leaders. The position of real leadership 

 is held by the animal that initiates, sta- 

 bilizes, or integrates behavior patterns, 

 whether these call for activity or for 

 quietude, and he (or she) may occupy the 

 apex position when the group changes loca- 

 tion or otherwise shifts to a new line of 

 activity. Often, however, the animal moving 

 in advance is not the real originator of the 

 movement. Other pertinent qualities or 

 tendencies include such items as freedom of 

 action, responsibility for others, and guid- 

 ance of them. In social and subsocial as- 

 pects of ecology we are primarily con- 

 cerned with the situation in which the 

 leader and the led all belong to the same 

 homotypic group, but important heterotypic 

 leadership also occurs. 



Leadership may or may not be associated 

 with social dominance. In flocks of hens, 

 leadershin often rests in the midsocial 

 ranks rather than with the alnha hen, but 

 even these birds are quite dependent on 

 being followed (cf. Fischel, 1927). Lead- 

 ership exists among ants, where individ- 

 ual-to-individual dominance is unknown 



(Chen, 1937a), and the leader is often de- 

 pendent on her followers. The raiding 

 columns of the American army ants (Eci- 

 ton) have a shifting type of leadership; the 

 ant or a small "pushing party" of ants at 

 the apex of the advancing column moves 

 forward less than an inch and turns back 

 to the advancing larger mass (Schneirla, 

 1933). 



Leadership in flocks of birds presents 

 many unsolved problems mainly related to 

 the difficulty of identifying individuals in 

 the field. In one heterotypic flock (Nichols, 

 1931) the real leadership of a flying flock, 

 as with hens, rested in the body of the 

 flock rather than with the single, conspic- 

 uous golden plover that flew out in front 

 after the slower flying black-bellied plovers 

 determined the direction; and these, in 

 turn, would deviate from a straight course 

 when the yet more slowly flying dowitchers 

 fell behind. 



Among groups of mammals the socially 

 dominant animal is often also the leader. 

 An exception is shown by the herds of red 

 deer of Scotland that have been carefully 

 studied by Darling (1937). During most 

 of the year the males remain away from 

 the herds of hinds and younger animals. 

 The leader of the hinds is an alert old fe- 

 male with fawn at foot. There is little evi- 

 dence of social dominance in such herds. 

 The stags enter the scene at the onset of 

 the rutting season, and each male rounds 

 up and dominates as many hinds as he 

 can. Still he is not the real leader, for in 

 case of danger the stag runs away, and 

 leadership is seen to remain with the ex- 

 perienced female that usually leads the 

 herd. 



These female herds often have subsidiary 

 leaders that help maintain strict watch, re- 

 minding one of the accounts of Sclater 

 (1900) concerning leadership in hordes of 

 African baboons. The baboons associate in 

 groups that may number a hundred indi- 

 viduals. When moving, the old males are 

 usually on the outskirts and form a rear- 

 guard. When resting, a sentinel or two are 

 always on the lookout for approaching dan- 

 ger. 



The comment of John Phillips (see Allee, 

 1931, p. 349) is worth quoting: 



"... The sentinel is exceedingly sharp 

 and detects the least noise, scent, or appearance 

 of man or leopard. In East Africa I have seen 



