WHY DO KANGAROO RATS (DIPODOMYS SPECTABILIS) FOOTDRUM AT SNAKES

We examined alternative hypotheses for the benefits of footdrumming in the presence of snakes by the banner-tailed kangaroo rat, Dipodomys s pectabilis, by testing whether the target of the signal includes consp ecifics, the predator or both. Footdrumming recorded in the field reve aled that rats altered their footdrumming signatures when drumming at snakes. In playback tests, however, neighbors failed to show any measu rable change in behavior to broadcasts of the snake drumming pattern, but mothers footdrummed significantly more than nonmothers in the pres ence of a tethered snake. Gopher snakes, Pituophis melanoleucus affini s, responded to footdrumming vibrations created by a mechanical thumpe r. Nonhungry snakes avoided footdrumming, while hungry snakes approach ed the seismic footdrumming. Snakes decreased stalking rates as footdr umming increased, but they spent more time stalking drumming than nond rumming rats. We conclude that D. spectabilis footdrums in individual defense and in parental care, rather than to Warn adult conspecifics. Footdrumming deters pursuit by informing the snake that the rat is ale rt and the chances of predation are low. We find little evidence that footdrumming startles, confuses, or harasses the snake. Hungry gopher snakes, however, may locate prey by eavesdropping on territorial footd rumming.