Use of different signaling modalities to communicate status by dominant and subordinate Heermann’s kangaroo rats (Dipodomys heermanni)

Dominance relationships in solitary species may be an important factor in the maintenance of long-term, stable relationships among territorial neighbors. We examined the mediation of intraspecific interactions in a solitary, territorial kangaroo rat, Dipodomys heermanni, and tested whether unfamiliar kangaroo rats establish a dominance hierarchy and then decrease aggression and increase communication (via footdrumming and sandbathing) after initial interactions and the establishment of a social structure. Results revealed that both dominance hierarchies and familiarization with particular individuals are likely to mediate social interactions. After only one pairing per dyad, an almost linear dominance hierarchy emerged, which became perfectly linear after a 90-min familiarization period. During the course of subsequent interactions between dyad partners, fighting decreased and non-agonistic communication increased. Dominant kangaroo rats sandbathed at higher rates than subordinates, possibly to deposit scent to advertise competitive ability, whereas subordinate kangaroo rats footdrummed from inside the burrow, which seemed to indicate an unwillingness to interact. We suggest the kangaroo rats use a conditional strategy when deciding to fight (be dominant) or withdraw (be subordinate) by employing different modes to communicate status and minimize the potential risk of injury during unnecessarily prolonged fights.