1810 



HORMONAL REGULATION OF BEHAVIOR 



not induce nest-building behavior. Further, 

 Leblond and Nelson (1937a, b) found that 

 nest-building behavior was induced in hy- 

 pophysectomized adults when they were 

 caged with young mice, which rather ef- 

 fectively disposes of the possibility of in- 

 duced hormone secretions. It appears rather 

 that stimuli from the young and the effect 

 of progesterone are complementary mecha- 

 nisms for maintaining nest-building be- 

 havior at a high level during the whole 

 period when such behavior is adaptive. 



B. BEHAVIOR DURING PARTURITION 



1. Patterns of Parturitive Behavior 



Behavior before 'parturition. In addition 

 to the nest-building behavior already dis- 

 cussed, other changes in behavior take place 

 during late pregnancy. Unfortunately, not 

 much attention has been paid to these as- 

 pects of behavior, but it is clear that the 

 special physiologic conditions of pregnancy 

 foster behavioral changes which contribute 

 to the preparation for behavior towards the 

 neonate. According to Schneirla (1950) a 

 pregnant cat reacts differently to her own 

 body from a nonpregnant female. More at- 

 tention is paid to the licking and grooming 

 of the body, the abdominal and pelvic re- 

 gions in particular being licked signifi- 

 cantly more than in nonpregnant cats. 

 Schneirla suggests that this licking, oc- 

 curring well before parturition, helps to 

 focus the behavior of the animal toward 

 that part of its body. Later, during par- 

 turition, its licking responses to stimuli 

 from the pelvic region will make a signifi- 

 cant contribution to the parturition itself. 



The preparturient female American elk, 

 which at other times lives gregariously in 

 closely integrated herds, goes into isolation, 

 avoiding other animals, with the result 

 (among others) that the newborn elk at first 

 associates only with its own mother (Alt- 

 mann, 1952). Similar observations have 

 been made on the European red deer (Dar- 

 ling, 1956) and other ungulates (Bourliere, 

 1954). 



During pregnancy, chimpanzees become 

 increasingly quiet, gentle, and friendly, and 

 less aggressive, both toward human keepers 

 and toward other chimpanzees (Yerkes and 

 Tomilin, 1935; Yerkes and Elder, 1937). 



This uncharacteristic gentle behavior per- 

 sists during lactation, except that if the 

 infant is removed shortly after birth, the 

 mother quickly returns to the usual type of 

 behavior (Nissen and Yerkes, 1943). On 

 the other hand, Wimsatt (1960) stated that 

 pregnant bats become restless and irritable 

 some time before parturition. 



It is probable that closer study of the 

 behavior of preparturient animals will yield 

 significant clues to the nature of the physio- 

 logic preparation for postparturitive be- 

 havior. 



Behavior at parturition. Although obser- 

 vations of behavior during parturition have 

 been made on only very few species, it is 

 clear that different types of mammals give 

 birth in different positions, and that the 

 position taken by the mother during par- 

 turition is a relatively constant character- 

 istic of the species. A number of ungulates, 

 and the elephant, give birth in a standing 

 position (Hediger, 1952). Other ungulates, 

 such as the American elk (Altmann, 1952), 

 and the guanaco (Hediger, 1952), may give 

 birth in a reclining position. Rodents char- 

 acteristically give birth sitting or crouching 

 on the hind legs ( Eibl-Eibesfeldt, 1958; 

 Dieterlen, 1959), whereas domestic cats 

 crouch and recline in different stages of the 

 process (Cooper, 1944). Some kangaroos 

 and other marsupials lie on the back dur- 

 ing parturition (Hediger, 1958). In some 

 species, such as the American buffalo, con- 

 siderable individual differences are seen; 

 some individuals give birth while standing, 

 others while lying down (McHugh, 1958). 



As will be seen, the positions taken by 

 animals of different species are related to 

 the manner in which they establish care of 

 the young, and may be of considerable im- 

 portance for the analysis of the development 

 of maternal care. Rowell (1960a) observed 

 that when the golden hamster pup begins to 

 emerge, the mother licks it with the rest of 

 her genital area, and that, at this stage, the 

 young appears to be treated as an exten- 

 sion of this area of the mother's body. The 

 parturient American elk lies down and licks 

 her flanks, vulva, and the adjoining area be- 

 fore the calf has begun to emerge. Then, 

 when the calf emerges, the cow licks it 

 (Altmann, 1952). Likewise in domestic 

 goats, the mother licks the kid as the kid 



