On Tuesday I returned back from one of the greatest adventures and learning opportunities of my life. For the past two months I have been living in Africa, studying and conducting research as part of my Animal Behaviour degree with Manchester Metropolitan University. This fascinating journey began in Tanzania, travelling around many conservancies such as Tarangire, Ngorogoro Conservation Area and The Serengeti. Alongside The College of African Wildlife Management we studied the local wildlife, ecology and issues such as human wildlife conflict. For the last six weeks we worked in Ol Pejeta Conservancy and Lewa Wildlife Conservancy, Kenya in association with Kenya Wildlife Service. The research project I was lucky enough to conduct was investigating the social structures and behaviour of the white rhino.
Rhino are in fact the closest living relative to equids, diverging from a common ancestor 55 million years ago (Rose et al, 2014). While black rhinoceros are mainly solitary and feed on browse, white rhinoceros have very similar behaviour to horses. They are highly social grazers who live in small herds. Both black and white rhino face immense pressure in the wild from poaching for their horn. In East Asia the horn is used in many traditional medicines, despite it being made of keratin, the same material as hair. Since 2007 the illegal ivory trade has trebled, increasing demand for horn significantly and decimating rhino populations across Africa. As a result of continued poaching the northern white rhino has now been declared extinct in the wild with only 3 individuals of the species existing in captivity. These precious individuals will live out the last of their days at Ol Pejeta Conservancy under 24 hour armed guard, and incredibly I had the immense privilege to include these animals in my study.
Despite being the most social rhino species, the social behaviour of white rhinos has received very little attention scientifically, with the last comprehensive paper published in 1975 (Owen-Smith). As the wild populations of southern whites faces such overwhelming pressure, long term conservation relies on captive populations to maintain genetic diversity. However, the captive population is failing. Only wild caught individuals breed in captivity, making this an unsustainable solution (Cinkova & Bicik, 2013). Nobody fully understands why captive white rhinos don’t breed, and various possible theories have been explored including behavioural reasons, hormonal, genetic or physical problems (Swaisgood, 2006). One possible theory is that the social structure of white rhinos is complex and not fully understood and so their social needs are not fully met in a captive setting. With this in mind this research project aimed to explore the social structures of white rhino and hopefully cast light on the present dilemma.
In total I spent approximately 65 hours formally observing both southern and northern white rhino in the conservancies. Myself and MMU research partner Ruth Spense identified each rhino individually and recorded their location and group size. I then recorded the identification of their nearest neighbour and any instances of affectionate or aggressive behaviour that occurred. Ruth has been recording the ratio of bites to steps taken while grazing, which gives an indication to grazing quality. The vegetation in areas where rhino were observed grazing was also measured so that comparisons between grazing quality and behaviour can be made.
During the observations I noticed that most rhino spend their time in very close, small groups. This normally consists of a mother and offspring, or a same sex pair. These close groups remain together all of the time and share a lot of affectionate behaviour. These smaller groups will also converge at periods each day to graze and sleep, and may number up to 7. Adult males spend time on their own or in pairs and move between larger groups. Many adult males may be present in a group at a time. Interestingly it is not always the same combination of individuals that come together each day, making the social composition fluid and flexible.
The vast majority of interactions between all individuals involve bond strengthening behaviour such as touching horns, face or bodies and maintaining close proximity. The rhinos are in fact highly affiliative, and will direct subtle affectionate behaviours towards their closest associations regularly. When individuals greet each other this is too is accompanied by gentle touches with their face and horn. Instances of aggression are incredibly rare and mild when they do occur. When aggression is present it appears to be in relation to competition for a mate or protecting offspring, much the same as documented in wild equids. In captive rhino the stressful provisions of food increases acts of aggression in line with resource holding potential (Cinkova & Bicik, 2013) also like their equine cousins. However due to the forage not being easily defendable in the natural setting no aggression in relation to food was observed. From my observations there is no evidence of a dominance hierarchy or any cohesion within the social behaviour of wild white rhino.
The results have not been statistically analysed, and more detail will undoubtedly come to light following this. Despite this a lot of information has arisen from the hours spent in the field. The social behaviour of white rhinos is remarkably similar to that of equids and is highly complex. Like horses they seem to have a pair bond, and their social behaviour relies predominantly on affiliative interactions. However, the rhino’s social organisation is complex, ever changing and flexible. In captivity perhaps denying the rhinoceros the ability to interchange is impacting their breeding success through limiting mate choice or creating stress from an unnatural social ethogram. Whatever the cause it is crucial that research begins to identify it to prevent the southern white rhino from meeting the same fate as the northern whites undoubtedly will.
Cinkova, I. & Bicik, V., (2013). Social and reproductive behaviour of critically endangered northern white rhinoceros in a zoological garden. Mammalian Biology, 78, pp.50–54.
Kenneth D. Rose et al. (2014). Early Eocene fossils suggest that the mammalian order Perissodactyla originated in India. Nature Communications 5, article number: 5570; doi: 10.1038/ncomms6570
Owen-Smith, R.N., (1973). The Behavioural Ecology of the White Rhinoceros. Dissertation Abstracts International, 34, pp.5256–5257.
Swaisgood, R.R., Dickman, D. M., White, A. M., (2006). A captive population in crisis: Testing hypotheses for reproductive failure in captive born southern-white rhinoceros females. Biological Conservation, 129, pp.468-476.