A mechanical device for monitoring the diel activity pattern of small burrowing mammals under natural conditions is described. The device has been used to estimate the time spent by the Indian gerbil, Tatera indica indica Hardwicke in foraging above ground and in an underground nest which is a part of the device. Activity patterns recorded with this device have confirmed observations that Tatera i, indica is nocturnal. The average time spent by this rodent outside the nest during an eight day study period was 318 min/24h. These rodents are generally active between 1900–0300 hrs, apparently with two peaks of activity, one between 2100–2200 hrs and the other between 0100–0200 hrs.