16 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 122 



during an encounter implies that chemical communication is taking 

 place; thus, the functional classification of sandbathing really includes 

 a marking function as well. In addition to the movements involved 

 in dressing the pelage, these animals may have definite marking 

 movements. 



Marking: Marking is a functional term including several behavioral 

 units. From a functional standpoint a marking pattern serves to 

 spread some chemical substance at a specific locus. Such a chemical 

 presumably has communicatory value. Many rodents utilize a mark- 

 ing pattern that involves a depression of the anal-genital region in 

 order to brmg these glandular areas into contact with the substrate 

 as the animal moves about in its living space. This is termed the 

 perineal drag. Urme and feces may serve as chemical markers in 

 addition to glandular exudates. When special glandular areas are 

 concentrated on other parts of the body such as the flanks or ventrum, 

 side rubbing or ventrum rubbing may be expressed as a marking move- 

 ment. The perineal drag is a movement common to all the rodent 

 species studied. Ventrum rubbing is a ritualized marking movement 

 show n by the genus Meriones. The latter genus is characterized also 

 by a large gland-field in the ventral epidermis. 



It should be noted that sandbathing can serve the dual function 

 of dressing the pelage and marking (Eisenberg, 1963b, c); thus, in 

 desert-adapted species the sandbathing behavior tends to be con- 

 centrated at a specific locus and can serve as a focus of activity for 

 two or more interacting individuals. 



Washing: Washmg (autogrooming) is displayed in a typical myo- 

 morph fashion (Burger, 1959). The chief modifications in movement 

 pattern are the results of morphological modifications. Hence, the 

 short forelimbs and short necks of the bipedal genera restrict the 

 movement of the head in the vertical plane and necessitate a rotation 

 of the head when it is washed with the forepaws. 



Burrow construction.— The desert-adapted rodents of the fami- 

 lies Cricetidae, Dipodidae, and Heteromyidae construct extensive 

 burrow systems that employ basic digging patterns involving the 

 forepaws and hind limbs (Eisenberg, 1963b). The teeth may be used 

 to gnaw into a hard substrate; Allactaga elator is most prone to gnaw 

 when constructing burrows. This behavioral trait is reflected in the 

 protruding dentition, which enables A. elator to gnaw into a flat 

 surface without a crack or crevice that would permit a starting point 

 for gnawing. 



Burrow waUs are packed by a pushing and patting motion of the 

 forepaws (Eisenberg, 1963b). This movement pattern is typical for 

 man}^ rodent species, and the nose and incisors may also be involved in 

 packing loose soil. Tatera and Meriones, when packing, employ the 



