Vocalisations of a North American subterranean rodent Geomys breviceps

Ecological restrictions of the subterranean environment have resulted in sensory adaptations in its inhabitants that limit communication below ground. Adaptations such as degenerate vision and reduced hearing capabilities influence the communicative methods employed by subterranean rodents. Due to the logistic difficulties of investigating life underground, little is known about subterranean rodent communication. Vocal repertoires have been examined in a limited number of subterranean species, but never in North American taxa. We examined vocal communication in Baird’s Pocket Gopher Geomys breviceps, a species indigenous to south central North America. Our results show that this species has a repertoire of 4 audible signals, 2 of which are only emitted during close-contact encounters. Energy of signals was concentrated within the frequency range correlating with pocket gophers’ greatest hearing sensitivity. Results are also consistent with the frequency requirements for efficient transmission in the subterranean environment. Corresponding behavioural contexts suggest that vocal communication is important for facilitating social interaction with G. breviceps. Because the Geomyidae extend the furthest into the fossil record and are exclusively solitary species, this group is of fundamental importance for considering evolution of communication in subterranean rodents.