Tuco-tucos’ vocalization output varies seasonally (Ctenomys pearsoni; Rodentia, Ctenomyidae): implications for reproductive signaling

Abstract

Tuco-tucos are subterranean rodents endemic of South America. Ctenomys pearsoni is a solitary species from southwestern Uruguay. Each individual occupies its own burrow and aggressively defends it, except for juveniles before dispersing and couples during reproduction. We tried to understand how these animals find a partner and how they know their reproductive state, avoiding to spend excess energy burrowing to locate those partners for reproduction and avoiding above-ground predation. We studied a C. pearsoni population in the field from June 2005 until March 2007, using individually identified animals, some fitted with radio-tracking collars. For their long-range vocalizations, we recorded the number of vocalizations, number of series (groups of notes composing the vocalization) emitted, time of day of the emission, and emitter identity. Samples were taken by listening to the emissions. Results show that the number of emissions changes along the year, being higher during the reproductive season. Males emit more frequently than females and do it throughout the year. Female vocalizations rise in number when reproduction starts and then decline in number through pregnancy and/or until juveniles disperse and also vary in length being longer during the beginning of the breeding period. These results suggest that female vocalization (i.e., repetition and duration) would inform about emitter’s location, sex, and reproductive condition.