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 spectabilis, by testing whether the target of the signal includes conspecifics, the predator or both. Footdrumming recorded in the field revealed that rats altered their footdrumming signatures when drumming at snakes. In playback tests, however, neighbors failed to show any measurable change in behavior to broadcasts of die snake drumming pattern, but mothers footdrummed significantly more than nonmothers in the presence of a tethered snake. Gopher snakes, PituophismdanoUucus affinis, responded to footdrumming vibrations created by a mechanical thumper. Nonhungry snakes avoided footdrumming, while hungry snakes approached the seismic footdrumming. Snakes decreased stalking rates as footdrummmg increased, but they spent more time stalking drumming than nondnimming rats. We conclude that D. spectabilis footdrums in individual defense and in parental care, rather than to warn adult conspedfics. Footdrumming deters pursuit by informing die snake that die rat is alert and the chances of predation are low. We find little evidence that footdrumming startles, confuses, or harasses die snake. Hungry gopher snakes, however, may locate prey by eavesdropping on territorial footdrumming. Key words: antipre- dator behavior, communication, deterrence, Dipodomys spectabilis, footdrumming, kangaroo rat, pursuit, snakes. (Behav Ecol 8: 404-413 (1997))