Dwarf mongooses use sex and identity cues in isolation calls to discriminate between callers

A comparison of individual distinctiveness in three vocalizations of the dwarf mongoose (Helogale parvula)

“…Although the level of correct classification for all three calls types was relatively low when compared to that of other studies (Briseño‐Jaramillo, Estrada, & Lemasson, ; Collins et al., ; Gillam & Chaverri, ; Leliveld et al., ), the PIC values were comparatively high (e.g., Bouchet et al., ; Salmi, Hammerschmidt, & Doran‐Sheehy, ). Previous research has shown that dwarf mongooses are capable of discriminating between individuals for each of the three call types (Kern & Radford, ; Rubow et al., ; Sharpe et al., ), suggesting that high levels of call individuality are not a necessity for individual recognition and discrimination. For example, although banded mongoose escort contact calls achieved low correct classification percentages, the acoustic distinction was sufficient to allow mongoose pups to discriminate between individual callers (Müller & Manser, ).…”

“…Unlike the other call types examined in this study, the isolation call—which showed the highest level of individual distinctiveness and the lowest degree of variation within individuals—appears to provide signalers with unequivocal incentive to advertise identity. Emitted by individuals that have become inadvertently separated from their group, this long‐distance call is used to notify the group and facilitate a reunion (Rubow et al., ). As in all the obligate, social Herpestids, lone individuals outside their group are very vulnerable to predation and suffer high levels of stress (e.g., Young & Montfort, ; Young et al., ).…”

“…Using Luscinia bioacoustics software (RF Lachlan version 2.0), we analyzed calls by Fast Fourier Transformation with the following settings: 1,024 points, Hamming Window, time step 0.36 ms, frame length 23.22 ms, and overlap 98.45%. We analyzed parameters that have been previously identified as important in determining individuality in the calls of dwarf mongooses (Rubow et al., ). These were the first and third quartiles of the power spectrum, the fundamental frequency at maximum, minimum, peak, and mean of the call, and mean Wiener entropy (means were calculated by the Luscinia program).…”

“…It consists of a single, high‐frequency call (5,931–9,000 Hz) which sounds indistinguishable from the snake call to the human ear, but which differs in duration, maximum frequency, and entropy (being slightly shorter, higher and with lower entropy values than the snake call) (Rubow et al., ). The isolation call serves to facilitate the lost individual's reunion with its group, and experiments have revealed that the mongooses discriminate between callers on the basis of sex and group membership (Rubow et al., ).…”

“…We assess one short‐range, intragroup social call (the “contact call”), one predator warning call (the “snake call”, which also has a recruitment function) and one long‐distance call used when a mongoose becomes separated from its group (the “isolation call”). Previous experimental work has demonstrated that dwarf mongooses discern and differentiate between individual callers for all three vocalizations (Kern & Radford, ; Rubow, Cherry, & Sharpe, ; Sharpe, Hill, & Cherry, ).…”