Rhino Ecology Project

Region: Botswana
During the 20th century, both black and white rhino subspecies became extinct in Botswana, due to poaching. In 2001, Botswana’s Department of Wildlife and National Parks (DWNP), with the help of Wilderness Safaris and the Trust, successfully reintroduced a number of black and white rhino into the Moremi Game Reserve. Before bringing them into the reserve, the area was assessed and considered suitable habitat for both black and white rhino. However, interestingly, both species have been moving off to occupy other habitats.

The primary objective of the project therefore is to identify key factors influencing the movement of reintroduced black and white rhino out of the habitat into which they were introduced. The identified factors will be used to draw recommendations relating to appropriate habitat into which rhino can in the future be released.

A hypothesis is that foraging and distribution patterns of both rhino species are affected both by a number of abiotic factors, such as slope and distance to water etc., as well as by a number of biotic factors such as predation, territoriality (behavioural relations with other species) and possibly poaching pressure.

The objectives will be met by:

1. Determining home ranges, movement patterns and distribution and comparing these between habitat types, sexes and seasons.
2. Sampling vegetation to establish food availability and plant species preferences.
3. Determining the response of rhinos to other species by means of observations

The research will be conducted on Chief’s Island within the northern part of Moremi Game Reserve in Botswana, making use of tracking GPS data recorded by the Anti Poaching Unit (APU) officers during regular monitoring patrols. In addition, animals will be tracked by spoor, identified by means of their ear markings and digital photographs will be taken of the individuals to assist with identification.

Vegetation will be sampled to establish food availability and plant species preferences by the rhinoceros. This will be done whenever an individual has been sighted or its spoor has been positively identified. Vegetation type, soil type and the presence of /distance to the nearest water body will be determined.

The rhino will be observed when they come into contact with other species and their response will be recorded, including whether the animal flees, fights, or ignores the presence of the other species. Finally, data from the Anti-Poaching Units on rhino mortality will be analysed versus habitat type and the presence of humans.

The results of the project hopefully will lead to a better understanding with regards to reintroductions in a free-ranging system, and provide a better understanding of the ecology of the two species. The project will improve and contribute to the paucity of literature on this specific subject, as well as increase the success of the reintroduction programme going forward, which in turn should enhance the marketability and sustainability of ecotourism in the area.

January 2010 Report
This project, which forms part of the Botswana Rhino Relocation and Reintroduction Project, is progressing well, albeit slower than anticipated. This is primarily due to limited access to the study area thanks to exceptionally high rainfall and flooding over the past year. However, to date 50 rhino (27 in 2001, 6 in 2006 and 15 in 2009) have been radio collared, six of which were successfully tracked over seven months, gaining a greater understanding of rhino habitat use in this protected area.

The Department of Wildlife and National Parks’ Anti-Poaching Unit has been providing security and monitoring the rhino on a daily basis since 2001, at the same time recording the GPS positions of the animals. Where radio transmitter lifespans expired, rhino were also tracked on foot. In order to determine the diet of various individuals, a method known as ‘back-tracking’ was used, where a rhino’s feeding path is covered on foot and all grass species consumed in a number of 1x1m2 quadrants identified. The preferred species in the diet can then be determined.

Three calves were born in 2009 bringing the total number of calves born in the reserve since 2001 to more than 23. Territorial fighting has recently been observed between the dominant males and a few newly recruited subordinate males, but with no known mortalities. Five territorial males have been identified in the study area.

This study has thus far shown that rhino distribution is largely influenced by the availability of water, food and vegetational cover. Rhino sightings and signs (rubbing posts, middens, scrape-markings, etc) were primarily located along the river channels during the dry season but were distributed more throughout the reserve during the wet season as water and food were readily available. Fieldwork will continue as soon as the floodwaters subside.

December 2008 report
Field work commenced in April 2008 and has been progressing well. At that stage only six radio transmitters were still functional, but a good picture had already emerged on rhino movements and we were able to find many of the other rhinos by relying on spoor identification. Fourteen individual animals are being tracked for two weeks per month. Dry season data was collected from April through October. Unfortunately heavy rains in November and December prevented the team from gaining access to the study site. However, we hope to start collecting wet season data by mid-January.

During the dry season we observed that rhino distributions were influenced by the availability of water. Data collection will continue throughout the wet season. Data will then be overlaid with a vegetation map of the Okavango Delta to establish whether there is any preference for a particular habitat type per season.

In the dry season, the rhinos foraged on seven primary grass species, namely: Cynodon dactylon, Urochloa spp, Chloris virgata, Digitaria eriantha, Brancychne spp, Panicum maximum and Eragrostis spp, with the Eragrostis spp being the most foraged species.

A total of nine rhinos have left the study area. Five of these animals were captured and returned to the safety of Moremi Game Reserve (MGR). There are currently two territorial adult male rhinos with clearly defined and well defended territories although they do overlap slightly. The dominant adult male is defending a large territory and has a number of females and five calves therein. The second male is defending a smaller territory with only two females present.

The population of white rhino in this study are free ranging animals that are therefore able to display an unrestricted, natural dispersal, better allowing us to understand home range size, habitat use and feeding preference in the wild. An investigation as to whether a preference is shown for a particular habitat and to identify key factors influencing the movement patterns of the rhino out of the habitat they were reintroduced into is essential from a management perspective. Additionally, the long-term benefits of establishing a successful breeding nucleus of white rhinos in an area they once occupied will allow for future reintroductions into other suitable areas.