Dingo Howls: The Content and Efficacy of a Long‐Range Vocal Signal

Abstract

Signals are shaped through selective pressures impacting their information content (i.e. ‘what’ is conveyed) and their efficacy (i.e. ‘how’ is it conveyed). In the case of long‐range communication, a signal's structure should both convey information and allow for detection and discrimination despite the effects of environmental variability during propagation. Canid howls are an ideal example of a long‐range communication signal, although research has mostly focused on the relationships between howls’ acoustic characteristics and their potential information content in wolves, Canis lupus spp., and coyotes, Canis latrans. In this study, we quantified these relationships in another canid, the dingo, Canis familiaris dingo, to determine how their howls compare to that of other wild canids. We found that dingoes’ howls are individually distinctive and may convey gender cues. Playback experiments indicate that dingoes can perform class‐level recognition of familiar and unfamiliar individuals on the basis of vocalizations alone. These results mirror findings for other wild canids such as wolves and coyotes. Lastly, propagation experiments demonstrate that this signal's structure can permit long‐distance detectability and discriminability. We discuss our results in relation to the putative functions of canid howls and propose avenues for future research.

Concatenation of ‘alert’ and ‘identity’ segments in dingoes’ alarm calls

“…This pattern of responses is congruent with previous findings that reported an increase in responses to unfamiliar howl vocalisations in wolves33 and dingoes29 and demonstrates that dingoes can perform familiar-unfamiliar discrimination. Furthermore, dingoes were able to learn vocal cues from howl vocalisations and generalize these to new calls (i.e.…”

“…To assess if dingoes’ responses varied according to the familiarity of howl segments (prediction 1) we used a composite ordinal scale, successfully used in previous research on dingoes’ discrimination abilities29. Responses were classified on a four-level scale with ‘low’, ‘medium’ and ‘high’ scores given when dingoes looked toward the speaker on 0–1, 2–3 and 4–5 calls without approach, while a response was scored as ‘strongest’ if it included an approach toward the speaker.…”

“…Dingoes’ responses to acoustic stimuli are typically short-lived and they naturally stop attending to stimuli after a few consecutive presentations29. Thus, we used the number of looks elicited as an index of attention level to test prediction 2.…”

“…‘individual signature characteristics’) appears conserved across howl segments of bark-howls and howl vocalisations28. Dingo howls (as opposed to howl segments) are produced singly or in bouts, often without any apparent external stimulus and allow for class-level recognition of familiar and unfamiliar conspecifics29 (Fig. 1).…”

Call and be counted! Can we reliably estimate the number of callers in the indri's (Indri indri) song?

“…wolves [ 31 , 32 ]; jackals [ 33 , 34 ]; gibbons [ 35 , 36 ]), however, it has been impossible to validate the minimum number of emitters recognizable in a group because recordings could not be supplemented by traditional survey methods. The difficulties in providing a reliable estimate of the number of singers in a chorus are many, from background noise masking to individual behaviors that may affect acoustic propagation characteristics [ 37 , 38 , 39 , 40 ].…”