The influence of intraguild carnivore competition on the behaviour and vocal repertoire of the African wild dog, Lycaon pictus
African wild dogs have become the most endangered large carnivore in Africa. Central to their predicament appears to be their need for enormous areas over which to roam and hunt, areas far larger relatively than those required by other sympatric large carnivores. One explanation that has been put forward is that the dogs need such large home ranges because they are forever kept on the move as they try to avoid competition and predation by the larger carnivores they share space with.
To explore this theory we are examining the vocal repertoire of African wild dogs, hypothesizing that if indeed they are a species “on the run” they should communicate in ways that minimize the risk of detection by eavesdroppers. Specifically then, they should tend to vocalize at frequencies that either cannot be heard by other animals, or that attenuate most rapidly through the environment, allowing them to communicate effectively within the pack whilst avoiding being overheard by nearby dangerous neighbours.
My recordings to date have shown that wild dogs do indeed favour high frequencies for the majority of their vocalisations, illustrated neatly by their typical and remarkable twittering calls that many observers have called “birdlike”. Indeed, I have discovered that many of their calls have elements extending well into the ultrasonic range. This however does not appear to be because such frequencies may be undetectable by their competitors as the calls containing ultrasonic elements concurrently contain audible frequencies with more energy in them. Consequently I have had to seek another explanation for the wild dogs’ use of these unusually high frequencies and am currently investigating whether they may aid individual recognition in a manner analogous to the postulated signature whistles of dolphins.
It remains the case that wild dogs are under pressure to avoid their dangerous neighbours and in support of this even the audible frequencies they emit are relatively high frequency. A further avenue of investigation I am pursuing then involves conducting sound transmission experiments to quantify how the various frequencies within the dogs’ calls are attenuated over distance, information that will shed light on how the various calls’ functions are served by the physical properties defined by their design.
In addition to this measure of how detectable wild dogs’ various calls are, I have been conducting playbacks of wild dog calls to both lions and hyenas. The reaction of these predators to the different calls is videoed to allow comparison and provide data on not simply the basic fact of transmission of the sounds but also, importantly, data about over what distances the sounds can be recognised and understood. This is of significance if the eavesdropper is to link the sound being heard with the potential for a meal. Finally, to fully explore what might be called the dogs’ auditory relationship with lions and hyenas I have been playing back lion roars and hyena whoops to resting dogs. Again I video the dogs’ responses, measuring changes in vigilance and pack movements and when possible making recordings of any vocalisations these playbacks provoke, be it alarm barks or twittering.
School of Psychology