PARENTAL BEHAVIOR 



1335 



ond litters may not be due to jjliysiologic 

 changes associated with maturity, which 

 are in turn to some extent reversed or over- 

 ridden by approaching senility. Hauschka 

 (1952) states that female mice of a strain 

 in which there is a certain amount of can- 

 nibalism toward the young showed a higher 

 frecjuency of eating the young with increas- 

 ing age. Hauschka defines age in terms of 

 the litter number, from the first litter 

 through the eighth. In this study, as in some 

 of the other experiments we have men- 

 tioned, age is confounded with experience, 

 so that it is not possible to say whether the 

 changing pattern of behavior is due to the 

 animals' experience or to growth changes, 

 or to some interaction between the two. 

 Controls for age and for previous pregnancy 

 and parturition without opportunity to re- 

 late to the young would be relatively simple 

 to arrange, but this has not been done. 



Similar problems are found in the few 

 reports of such work with birds. Verlaine 

 (1934) reported that domestic canaries 

 which built successive nests tended to build 

 better nests later in the season. He implied 

 that this is the result of practice, but it is 

 by no means certain that this is so, because 

 there is no control for the effects of seasonal 

 changes in hormone secretion. 



Saeki and Tanabe (1955) found that pro- 

 lactin injected into adult hens with previ- 

 ous brooding experience induced incubation 

 l)ehavior, whereas the same treatment ad- 

 ministered to immature pullets did not have 

 this effect. Here again, the relative effects 

 of previous experience, of age, and of endo- 

 crine condition (the experienced hens were 

 laying eggs before being injected) are not 

 clear. 



Craig (1913, 1918) reported that a female 

 ring dove which was never bred, nor had a 

 nest or nesting material, may lay an egg 

 on the floor, but an experienced dove will 

 withhold the egg until a nest is available. 

 Mr. Philip Brody and I, in the course of an 

 experiment on a different problem, have 

 verified this; in our observations, the ex- 

 perienced and inexperienced birds were of 

 the same age. 



It is apparent that, although there are 

 many suggestive indications that the first 

 breeding experience may have an influence 

 on the nature and efficiency of subsequent 



breeding behavior, the problem of behav- 

 ioral changes between first and later breed- 

 ing episodes deserves much closer and better 

 controlled study than has yet been given to 

 it. Attention should also be paid to the 

 probability that phyletic differences in the 

 role of such experience may be very impor- 

 tant (Beach, 1947a, b; Aronson, 1959). 



Nature of changes in behavior during 

 THE breeding EPISODE. Beach and Jaynes' 

 (1956a) oijservations indicate that some im- 

 provement in retrieving behavior occurs as 

 a result of practice during the lactation pe- 

 riod (see also Seitz, 1958). A number of 

 other observations and experiments suggest 

 that, at least in many mammals, the experi- 

 ence of the mother during each stage of the 

 period of maternal care, from parturition 

 on, contributes to the development of be- 

 havior during successive stages. 



Blauvelt (1955) reported that the asso- 

 ciation between newborn domestic goats 

 and their mothers during the period im- 

 mediately after birth seems to be a very 

 important part of the process leading to the 

 establishment of the mother-young rela- 

 tionship. A parturitive mother of this spe- 

 cies licks the kid as the kid leaves her body. 

 The kid, lying on the ground, bleats, and 

 the mother stands with her head pointing at 

 the kid until it can stand and walk to her. 

 If the mother's head is held so that she can- 

 not lick the kid during parturition, and she 

 is taken away for a short time, she does not 

 lick the kid again when she has returned, 

 and contact with the kid takes a long and 

 variable time to establish. If a 1-hour-old kid 

 is separated from its mother for just a few 

 minutes, the mother is very disturbed when 

 the kid is reintroduced. If the kid is fed by 

 the mother before the two are separated, 

 then the re-establishment of their relation- 

 ship occurs much more quickly after the 

 kid is returned than if the two are separated 

 before the kid is fed. In 6 cases in which the 

 kids were separated from their mothers for 

 20 or 30 minutes starting at birth, none was 

 able to establish a successful relationship 

 without help from the experimenter. Her- 

 sher, Moore and Richmond (1958) removed 

 24 newborn kids from their domestic goat 

 mothers for periods ranging from Vk to 1 

 hour, starting 5 to 10 minutes immediately 

 following birth. When the kids were re- 



