Territorial defense and advertisement by footdrumming in bannertail kangaroo rats (Dipodomys spectabilis) at high and low population densities

Summary Behaviors associated with territorial defense of large dirt mounds by bannertail kangaroo rats (Dipodomys spectabilis) at high and low population densities are reported. Rats were observed for 640 h during three summers and one spring from 1980–1982 in SE Arizona.Bannertail kangaroo rats defended their territories by footdrumming, as a long-distance warning signal, and chasing as a closer-distance threat. They footdrummed on or near their mounds spontaneosly during the night, in response to neighbors' footdrums, and durint mound challenges. There were no sexual differences in footdrumming, and juveniles frequently performed the behavior. The low frequency sounds were within the auditory sensitivities of the rats and footdrumming patterns differed somewhat between individuals. A playback experiment provided preliminary evidence that rats can differentiate between the footdrums of neighbors and strangers. When a bannertail visited the mound of another bannertail the mound owner actively defended its mound and immediately chased the visitor away. Fighting and mound challenges occurred infrequently, and the uniformly dispersed distribution of mounds suggested an effort by rats to avoid mutual interference.When population densities were high, dispersing juveniles built new mounds, consequently, distances between mounds decreased. Rats responded by tolerating closer neighbors, spending more time active on their mounds, and visiting neighboring mounds less. Adults increased footdrumming rates at high population densities, but juveniles footdrummed at high rates regardless of the population size.