RODENT ETHOLOGY — EISENBERG 



21 



The onset of agonistic behavior is not always immediate. In 

 figure 3, the time course of an encoimter between a male and female 

 Perognathus parvus is treated in consecutive 100-second intervals. 

 One may notice that on the day preceding estrus the male exhibits 

 contact-promoting and sexual patterns during the first 100-second and 

 third 100-second periods. During the second and fourth 100-second 



i 



C S D 100 C 



A 



D 200 C S D 300 



S D ICO C S D 20O S D 30O S D 400 



C S A D 100 C 



1 



Figure 3.- — -Changing proportions of male Perognathus parvus behavior through the estrus 

 cycle of his partner (A=day before estrus; B = day of estrus; C=day following estrus; 

 ordinate= percentage of all acts for each 100-second interval; abscissa=lst, 2nd, 3rd, 

 and 4th consecutive 100-second periods of encounter; s=all sexual acts; c=all contact- 

 promoting acts; A=all agonistic acts; D=all individual behaviors). 



periods, the male exhibits mostly individual behavior patterns that 

 include digging and kick back, sandbathing, exploration, and sitting. 

 On the day of estrus, sexual behaviors predominate throughout the 

 400 consecutive seconds. The day following estrus shows a gradual 

 tendency for agonistic behavior to increase throughout the encounter. 

 During the first 100 seconds, the male attempts contact and sexiuil 



