Kenya remains as one of the last remaining strongholds for the Eastern Black Rhinoceros (Diceros bicornis michaeli) and is continuing to make huge strides in protecting this critically endangered species. This is largely as a result of targeted protection, reducing poaching, and translocating rhinos to new areas. Tsavo itself has become an invaluable conservation area for black rhinos, with many residing in Tsavo’s Ngulia Rhino Sanctuary and the Intensive Protection Zone (IPZ).
Successful conservation strategies are rooted in understanding the animal in question. For example, tracking the migration routes of elephants helps us understand the impacts of infrastructure developments and enhances elephant conservation.
Unfortunately, as a result of their small populations and elusive nature, there are still large gaps in the knowledge of black rhino. This week’s article hopes to shed some light on to how these large reclusive mammals communicate with each other.
Rhino socialisation
For many years black rhino were thought of as largely solitary creatures, with the only strong bond between a mother and calf. Bulls and females can also form a temporary consort relationship during mating.
Although this assumption is largely true, recent footage released by the BBC has shown a group of rhinos socialising near a watering hole which indicates that these creatures may have a more complex social system then previously thought.
Experts suggest in lush habitats where the competition for resources is reduced, the black rhino’s territorial nature is also reduced, leading to increased direct socialisation.
Regardless, even in low resource habitats, black rhinos have developed an intricate communication system that allows them to pass on lots of important information without having to meet each other.
Black rhino’s home range
Firstly we must understand how a rhino’s territory works. Black rhinoceros establish home ranges, between 2.25-14.39 km2, within this home range there will be important resources such as water and vegetation. Each home range will have very little overlap and will be home to a group consisting of one dominant male, and one or more adult females, the dominant male may also tolerate some immature bulls.
As dominant bulls are very protective of the females and resources within their home range, they will fiercely defend it against intruders. To prevent unnecessary deadly fights taking place, black rhinos employ various olfactory tactics to clearly demarcate their territory and let intruders know they are not welcome.
Dung middens: information centres for rhinos
A very interesting form of communication, used by both white and black rhinos alike, is dung middens. Dung middens are specific spots within a rhino’s home range, where the rhinos will regularly defecate. The midden plays a role as an information centre for all the rhinos in the area. Including information regarding the age, sex, territorial and oestrus state of the rhinos using the midden.
Middens are commonly placed along feeding tracks, near important resources such as water or scattered randomly through a rhino’s home range.
Although the use of middens for black rhinos has not been extensively studied, as a result of their low populations and more solitary nature, for white rhinos, scientists have discovered a complex strategy to how the white rhinos will communicate with one another, which researchers suggest applies to black rhino as well.
Within a dominant bulls territory, there can be up to 40 middens, which the bull will use regularly as he patrols his area. When using a midden the bull will defecate in the centre of the midden, which can sometimes be up to 40 metres in diameter, before trampling the dung and spreading it around the area.
This behaviour not only ensures that the dominant bull’s scent is the most prominent in the midden but it also means that as the rhino patrols his territory his scent is spread along the ground from his feet, which can help demarcate the area and aid in navigation.
Rhino calling cards
If a female comes across a midden she will smell the midden, in order to get an idea of the age and status of the other rhino’s using it. She will then proceed to defecate on the edge of the midden, therefore leaving her “calling card” for the dominant bull. If the cow is in oestrus, the bull will be able to tell from the scent.
If an adolescent bull comes across the midden, not unusual behaviour if the young rhino needs to access an important resource such as water, he may also defecate on the outskirts of the midden to let the dominant bull know he passed through.
Challenging bulls
When a bull who wants to challenge for another bull’s territory, usually a young bull who has reached full maturity, finds a midden, he will deliberately defecate in the centre of the midden and spread the dung around, in an attempt to override the dominant bull’s scent.
This behaviour is a direct challenge to the dominant bull’s status and will usually lead to a fight for dominance. These fights can be extremely brutal, with estimates suggesting that 50% of natural rhino deaths are as a result of bull territorial fights.
Unfortunately, in resource-poor areas, bulls often struggle to survive when displaced from a territory. If the fight doesn’t kill them, they may be pushed into an undesirable, small territory, leading to starvation. This highlights the need to protect habitats from human encroachment and allow growing rhino populations to expand into new areas.
The communication methods used by black rhinos reveal a fascinating aspect of their social lives, one built in order to maintain a strict hierarchy and reduce conflict. The use of dung middens as information centres for rhinos allows them to relay important information without ever needing to meet. Black rhino are famously aggressive creatures as a result of high competition for resources, so the use of olfactory information centres allows them to communicate without causing any unnecessary conflict.
Studying these middens can give crucial information that can help rhino conservation. Researchers have already begun identifying rhino middens, using satellite and infrared technology, in order to track rhino populations.
With the ongoing success of rhino conservation in Kenya, we hope to learn more about these fascinating creatures which, in turn, will aid conservation efforts further. If you would like to find out how you can support Tsavo Trust’s efforts to protect and monitor the black rhino to make sure these amazing animals are protected, follow this link.