22 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 122 



behavior; some agonistic iiiteniction also occurs. In the second period 

 of 100 seconds, agonistic behavior increases and some contact-pro- 

 moting behavior remains. In the third and fourth 100-second periods, 

 the male alternates between agonistic behavior and individual acts 

 of digging and sandbathing. 



The reversion to agonistic patterns on the day following estrus 

 was examined in detail by the successive encounter technique. Tables 

 13 through 15 indicate the reversion to agonistic behavior or avoidance 

 on the day after estrus. The conclusion is evident: certain species of 

 rodents such as the heteromyid Liomys pidiis, Perognathus calijornicus, 

 P. parvus, and Dipodomys panamintinus and the gerbillid Gerbillus 

 nanus are prone to avoid or react in an agonistic fashion to one another 

 except for the male-estrous female sitiuxtions, whereas Allactaga elator 

 and Aleriones unguiculatus exhibit contact-promoting behaviors 

 outside of the estrous condition of the female. 



Whether soHtary or social, chemical communication is implied 

 in such postm'es as the naso-nasal or naso-anal configurations. In 

 such semitolerant forms as Meriones unguiculatus, marking by the male 

 plays an important role in an encounter. The desert-adapted species 

 are prone to exhibit sandbathing during an encounter and in the 

 intolerant species there is generally an exchange of sandbathing loci 

 in order that the male may become familiar with the female's odor 

 before achieving physical contact. The role of sandbathing in social 

 integration has been discussed for the Heteromyidae in previous 

 publications (Eisenberg, 1963b, c). Table 16 includes sandbathing 

 data for three species: Allactaga elator, Meriones unguiculatus, and 

 Gerbillus nanus. It is interesting to note that significant overlap 

 between male and female sandbathing loci occurred only in the G. 

 nanus encounters. This is in accord with the general theory since 

 G. nanus is the only noncontact species of the thi'ee. The species 

 conforms to the pattern of sandbathing during an encounter as out- 

 lined in previous publications for the intolerant Heteromyidae. There 

 can be little doubt that chemical substances left in the course of sand- 

 bathing by G. nanus induce further sandbathing by an approaching 

 conspecific. The exchange of chemical signals is thus a distinct 

 possibility. 



A further consideration of tables 12 through 14 points out some 

 interesting aspects of behavior. During a male-female encounter on 

 the days preceding or folloAving estrus, the male exhibits more sand- 

 bathing and/or digging and kicking back than on the day of estrus. 

 This is especially noticeable in the encounters with P. parvus and D. 

 panamintinus. The digging and kick-back patterns exhibit all the 

 characteristics of classical displacement activity and often follow a 

 bout of preUminary sexual behavior or chasing. In both of the pre- 



