Background & justification
The brown hyaena (Hyaena brunnea) is listed in the (IUCN) Red Data Book of Endangered species where its status is given as near threatened. In general brown hyaenas play a very important role as scavengers in the ecosystems they occur, especially on nature reserves and game farm areas where other scavengers such as spotted hyaenas and vultures no longer occur. Management of Rietvlei are concerned that the brown hyaena numbers on the reserve might be declining, due possibly to extensive urban development around the reserve. An additional concern is that in brown hyaena society all the mating is carried out by nomadic males who only visit the clans sporadically (Mills, 1982b). Intensive urban development around Rietvlei and the upgrading of the electric fence in 2003 may reduce the probability of these meetings occurring. No active den sites have been located by either management staff (pers.comm) or the public in the last 5 years.
In the IUCN's 'Hyaena action plan' a few projects were suggested, of which two are mentioned:
- Survey the status and distribution of the brown hyaena in the urban areas of Gauteng Province in South Africa. Objective: To establish the presence of the brown hyaena in an urban habitat, as there is evidence of their presence around the cities of Pretoria and Johannesburg. To assess the viability of the population and the risks it faces, and to search for ways the brown hyaena can coexist with humans in urban areas.
- To promote hyaenas as tourist attractions, and investigate the setting up of feeding sites (hyaena restaurants), particularly in urban or semi-urban areas, and encourage people to visit these in order to view hyaenas.
To inform the general public, especially those living in the proximity of Rietvlei and those using the Delmas road, about the brown hyaenas on Rietvlei and their ecological importance.
Study Area: Rietvlei Nature Reserve
Rietvlei belongs to the City of Tshwane Metropolitan Municipality and was established in 1929 to supply the city with clean drinking water. The reserve covers an area of approximately 3870ha, of which the dam covers 204ha when full.
Rietvlei is situated in the central variation of Bankenveld 61b, which forms part of the false grassland types (Acocks,1988). Only 5% of this veld type is protected in conservation areas. Rietvlei falls in a summer rainfall area and has an average rainfall of 725 mm a year. The summer temperatures can reach a maximum of 34 °C and in winter a minimum temperature of -2 °C. The winters are dry and frost occurs regularly, which is a typical highveld climate. The biggest threats to the reserve are development and alien or exotic species.
The objectives of this study are:
- To determine the size and population structure of brown hyaenas on Rietvlei;
- To determine the degree of relatedness of brown hyaenas on Rietvlei;
- To determine the reproductive demography of brown hyaenas on Rietvlei, and what dispersal patterns exist;
- To determine the diet of brown hyaenas on Rietvlei and to assess the degree of interspecific competition or possibly facilitation with a re-introduced cheetah (Acinonyx jubatus) male coalition, numerous black-backed jackal (Canis mesomelas) and bushpigs (Potamochoerus porcus).
The following questions will be answered:
- How many brown hyenas are there on Rietvlei Nature Reserve?
- What is the sex ratio of these hyaenas?
- What are the ages of these hyaenas?
- Are they currently breeding on the reserve?
- Are the individuals related to each other?
- If they are breeding successfully on the reserve, how many of them are dispersing?
- If there are some of them dispersing from the reserve, where do they go to and what is the survival rate?
- What do the brown hyaenas on Rietvlei feed on?
- To what extent does the brown hyaena compete for food against the cheetahs, black-backed jackals and bushpigs on Rietvlei?
- Does Rietvlei nature reserve play an important role in the conservation of brown hyenas in South Africa?
Materials & Methods
The majority of observations will be done at night by making use of a four-wheel-drive vehicle and a hand-held spotlight or night vision scope. The brown hyaenas will be fitted with GSM/GPS/VHF radio collars, manufactured by African Wildlife Tracking. These cellphone collars make use of the GSM cellphone network to communicate the stored data via the internet & Google Earth. Rietvlei has excellent cellphone coverage as well as a detailed Google earth map due to it's urban location. During the immobilization procedures information on body morphometrics, tissue and blood samples will be taken and the individuals will be sexed. The animals will also be placed into one of five age classes based on tooth eruption and wear, particularly with regard to the wear of the third premolar in the lower jaw, after Kruuk (1972) and Mills (1982). Camera traps will also be used to determine the animal movements on the reserve as well as the brown hyaenas population size. The camera traps will be placed at river crossings and game paths.
By answering this projects questions, valuable data on "urban" brown hyaena socio-ecology will be collected, which can then be used in brown hyaena conservation and management. Rietvlei Nature Reserve's management will have a good idea of what the current brown hyaena status is on the reserve and will then be able to make sound management decisions. This project can be the start of a 'greater Gauteng brown hyaena project', of which we then can manage the brown hyaenas in the Gauteng area as a metapopulation. Data from this project can be compared to previous and current ongoing brown hyaena studies from southern Africa.