Dropping in on the Eastern Riverine Rabbit population
Dr Samantha Mynhardt and Esther Matthew, the EWT’s DRYLANDS CONSERVATION PROGRAMME
-  The Critically Endangered Riverine Rabbit is regarded as one of Africa’s most endangered mammals, threatened predominantly by habitat transformation across the Karoo, resulting in a limited geographical distribution and seemingly small population size. The species is known from two populations: one in the Nama Karoo, where it was first discovered near Richmond in 1902, and one near Touwsriver in the Succulent Karoo, where the second population was discovered in 2003 (Figure 1). However, more recently in 2018, yet another, third population of these rabbits was discovered (through the correct identification of a roadkill specimen) just west of the Baviaanskloof, approximately 250 kilometres east of the known distribution. Research on the first two populations has been ongoing, however little to nothing is known about the third, most recently discovered population.
- The Endangered Wildlife Trust’s Drylands Conservation Programme has been working on Riverine Rabbit conservation for over 20 years and has initiated a concerted effort to better understand this newly discovered population. Our aim is to investigate the geographic distribution of the species and any possible geographic links to the other two populations, and to gather genetic material to investigate genetic connectivity between the populations.
- Earlier this month, three members of our team embarked on a field trip to collect Riverine Rabbit samples for this purpose. Dr Samantha Mynhardt is sampling rabbit scat (droppings) from all three populations for DNA sequence analysis, in order to map distributions and understand genetic connectivity, while Esther Matthew and her trained scent-detection dog, Delta, are assisting with establishing connections with farmers in the area, accessing properties, and locating (sniffing out) scat in the field. Delta, a two year old Border collie, is being trained to help us distinguish between the scat of different lagomorph species (hares and rabbits) in the field, to help increase efficiency.
Figure 1: Map illustrating the known extent of the three Riverine Rabbit populations occurring in three biomes across two provinces.
The Eastern population is located roughly between Uniondale and Willowmore, west of the Baviaanskloof. The species was described in 1902 from Nama Karoo specimens (northern population). The southern population was discovered in 2003 and the eastern population in 2018.
- We surveyed four properties where our camera traps have detected Riverine Rabbits over the past couple of years, as well as an additional site, where the team spotted a live rabbit in the road. Rabbit scat was found at all the sites, in varying levels of abundance, and a total of 41 samples was collected from the five properties (eight distinct geographic sites). Samantha will extract DNA from a selected subset of these samples for genetic analysis. The DNA sequences will allow us to identify species, i.e. verify that the droppings are those of Riverine Rabbits, map geographic distributions, and investigate genetic connectivity between these samples and those of the other two populations.
- Ultimately, the insights we gain from the population genetic analyses of these samples, regarding genetic connectivity of subpopulations, genetic diversity of the population as a whole, and of the subpopulations, and potentially also population size estimation, will help to inform and guide conservation management of the species. Perhaps the genetics will also unlock some of the secrets of the past distribution and origins of the populations.
- This project is supported by our longest standing funder for Riverine Rabbit conservation work, the Zoological Society for the Conservation of Species and Populations (Zoologische Gesellschaft für Arten- und Populationsschutz – ZGAP). The team’s transport to sites is made possible by Ford Wildlife Foundation.