Hear the Kruger call: the shrill cry of a fish eagle gliding over the floodplains; the rumbling sound of a lion as dusk settles in; the thundering hooves of a buffalo herd fleeing into the undergrowth from a predator. These are all nature’s melodies. These are all sounds that resonate in our souls, and that which we know to be synonymous with an authentic bushveld experience. But, there is so much more to the songs and calls of the wild than this. From communication to foraging, wildlife have evolved their own languages into a range of patterns and frequencies across the spectrum of species (many of which humans do not yet fully understand).
Ngwenya delves into the intricacies of wildlife communication:
Hyena
Hyenas are highly intellectual creatures that operate in large clans. These clans have social structure and a range of rules regarding their territory, hierarchy, the hunt and protection. Naturally, this means they require complex communication to uphold their system; one of the widest ranges in communication found in mammals, as a matter-of-fact. The most well-known of the hyena’s sounds is probably the hoot-laugh and giggling, which has dubbed the species with the name “laughing hyena”. While humans associate loud laughter with joy and relaxation, to hyena’s it actually signals distress and tension. The other most prominent call is the whoop which is a loud call that ranges in pitch. The whoop is used to communicate when out of visual range and can actually distinguish hyenas from one another. It is believed that these calls can signal the sex, age and status of the hyena to others. Scientists continue to study the vocalisations of hyenas, with growling being the most obscure. Hyenas are believed to use growling and body language in different combinations to communicate different meaning, the intricacies of which are still being uncovered.
Coucal
The coucal is one of 27 species of the genus Centropus, though you may be more familiar with the term cuckoo. Many of these medium-to-large birds are named for the sounds they make, or the birdsong they imitate. The two species most prominently found in the Kruger National Park are the Burchell’s Coucal and the Black Coucal. Coucal’s are widely known for the gurgling sound that accompanies their song, which many associate with a babbling brook. In fact, their local name in Kenya translates to “The Water Bottle Bird”. Their birdsong not only imitates water but has been closely studied and revealed to be linked to periods of downpour. Coucal’s will often sing before or after rain, when humidity is at an all-time high. Coucals, and birds in general, are able to produce their melodies due to an organ that only they possess: the syrinx. This vocal organ is found at the base of the trachea and produces sound when air is forced through it. The membranes of the syrinx walls vibrate when this happens; causing an oscillating effect that produces intricate birdsong.
Elephant
Elephants are known to have some of the most complex language systems amongst all wildlife. They are able to produce a range of idiosyncratic sounds, ranging from vibrations and rumbling to barks and snorts. Elephants mostly communicate using a low rumble which is produced at such a low frequency that it is seldom heard by human ears. The low rumble can be heard or felt as vibrations, by other elephants, up-to 10km away! This form of communication travels as vibrations with sound pressures reaching 117 decibels. The receptors of an elephants’ feet, known as Pacinian corpuscles, are highly sensitive and share a direct link to the somatosensory cortex of the brain, which is responsible for processing touch. The PC receptors are localised around the edges of the foot; elephants have been documented pressing their feet more firmly onto the ground to enlarge the surface area of contact so that they can hear better!
While this explains how elephants can hear one another, how exactly do they vocalise? Until recent studies conducted by the University of Vienna, scientists weren’t sure if elephant’s communicated through electrical impulses, known as AMC or active muscular contraction, or by the MEAD or myoelastic-aerodynamic method. Domestic cats use AMC to purr, while humans communicate via the MEAD method. While it is difficult to test for AMC, as it requires muscle contractions produced by brain signals, Christian Herbst at UV was able to test MEAD. His team obtained a deceased elephant’s larynx, which they connected to an airflow system. In this way, they could move air over the vocal cords of the larynx, which in turn mimicked the low rumblings and thus put the debate to rest on how elephants vocalise.
This is just three species’ ways of communicating and vocalising, but every wild animal has its own language to communicate with one another, ward off danger or to simply add a sweet song to the chorus of the bush. Wildlife also make use of a number of tools to effectively communicate that surpass sound, and these intricacies will continue to interest scholars and enthusiasts alike. All we have to do is pause and listen to the sounds of the Kruger.