Ontogeny of long-range vocalizations in a Neotropical fossorial rodent: the Anillaco Tuco-Tuco (Ctenomys sp.)

Abstract

33 Vocalizations became progressively longer, but the series types shown by adults were evident 34 in juveniles at an early age. All three acoustic features of series (triad) notes studied correlated 35 with age in both sexes (duration 90% increased through development, while bandwidth 90% 36 and peak frequency decreased). LRV developed normally in juveniles acoustically isolated from 37 adults, supporting the vocal tract maturation hypothesis and possibly rejecting the vocal 38 learning hypothesis. Juveniles emmitted a higher proportion (7.4%) of abnormal vocalizations 39 than adults (0.3%), as expected in the development of any complex behavior that requires 40 practice to be mastered. The maturation of the LRV occurred well before the sexual maturation, 41 presumably due to the protracted time needed to acquire or build a burrow system long before 42 mating is possible. We propose that protracted vocal development is another component in the 43 slow developmental strategy of Ctenomys and subterranean rodents in general.

Untitled

“…are subterranean rodents that produce long-range vocalizations (LRVs) of high intensity, broadband and low frequency. These vocalizations are essential for long-distance communication between individuals in different tunnel systems (Schleich & Busch 2002, Amaya et al 2016. Multiple lines of evidence suggest that LRVs are territorial signals that facilitate the maintenance of individual territories and minimize aggressive encounters, especially between males (Francescoli 1999;Schleich & Busch 2002;Amaya et al 2016).…”

“…These vocalizations are essential for long-distance communication between individuals in different tunnel systems (Schleich & Busch 2002, Amaya et al 2016. Multiple lines of evidence suggest that LRVs are territorial signals that facilitate the maintenance of individual territories and minimize aggressive encounters, especially between males (Francescoli 1999;Schleich & Busch 2002;Amaya et al 2016). Despite their behavioral importance, the LRVs of adults of only three of the more than 60 recognized species of Ctenomys (Bidau 2015) have been characterized in some detail (Francescoli 1999, Schleich & Busch 2002, Amaya et al 2016.…”

“…Multiple lines of evidence suggest that LRVs are territorial signals that facilitate the maintenance of individual territories and minimize aggressive encounters, especially between males (Francescoli 1999;Schleich & Busch 2002;Amaya et al 2016). Despite their behavioral importance, the LRVs of adults of only three of the more than 60 recognized species of Ctenomys (Bidau 2015) have been characterized in some detail (Francescoli 1999, Schleich & Busch 2002, Amaya et al 2016. Juvenile LRVs were simply mentioned in C. talarum (Zenuto et al 2002) and C. mendocinus (Camin 2010), but there is no detailed information on the developmental modes, pathways or developmental times of LRVs.…”

“…In normal vocalizations, each series begins with a note that is followed immediately by a soft note, but adults occasionally produce structurally abnormal series by adding a soft note before the initial note (Amaya et al 2016). Depending on the number of notes sandwiching soft notes, series can be classified as dyads (two notes, a soft note), triads (three notes, two soft notes), or tetrads (four notes, three soft notes) (Amaya et al 2016). In contrast, individual notes are single notes emitted at a faster rate in succession and are always given after the series (Figure 1).…”

Untitled

“…In the second 280 type, the series was conformed by a single monad that consists of a single note followed by a 281 soft-note ( Figure 3D). Monads are unknown in adults (see Amaya et al 2016). …”