To stay or not to stay: the contribution of tactile and thermal cues to coming to rest in newborn rabbits.

Newborn rabbits, like other altricial mammals, demonstrate thermotaxis and when placed on a thermal gradient locate and come to rest at physiologically appropriate temperatures. Little is known, however, about the sensory-motor components contributing to the in energetic terms important decision of the young to cease locomotion and come to rest. We investigated the behavior of newborn rabbits on two thermal gradients; linear in which pups could use tactile cues from the arena wall, and concentric in which pups were unable to use such cues. On both gradients pups located the warm, thermal-neutral area within the 200-s test time, thereby demonstrating their ability to orient appropriately using thermal cues alone. Unexpectedly, however, pups on the concentric gradient failed, or took significantly longer, to come to rest than pups on the linear gradient. Since the speed of locomotion of pups on the linear gradient was significantly slowed when they were in contact with the arena wall, and in most cases they came to rest in contact with it, we suggest that not only thermal but also tactile cues may be important in bringing young mammals to rest in a thermally appropriate environment.