Botswana Rhino Ecology Project
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.
