Spotted Hyena (Crocuta crocuta)
Arguably seen as one of the most successful large carnivore in Africa, spotted hyenas (Crocuta crocuta) are often overlooked compared to other, more charismatic carnivores. Currently ranked as least concern by the International Union for Conservation of Nature (IUCN) Red list of threatened and endangered species, it comes to no surprise as to why hyenas are overlooked when hyenas are abundant. Their wide dietary range, high tolerance levels towards disease, have made them a truly successful predator in a human-dominated landscape. Perhaps because hyenas are so successful and widespread they are seen as less important within the assemblage of large carnivores. Unfortunately, it has been noted that spotted hyena populations are beginning to decline. Most of this is due to population fragmentation.
For the first time in the history of the reserve, we are now also monitoring the spatial-temporal movements of both brown hyena (Hyaena brunnea) and spotted hyena in the Northern Tuli Game Reserve (NTGR). The addition of these two large carnivore species is a key factor in better understanding the complex drivers and relationships that exist in a savanna ecosystem. With the ongoing utilization of remote camera traps and annual calling-station surveys to monitor population distribution and abundance, the newly deployed GPS radio collars will give us an advanced insight, specifically on the movements of these two carnivore species in addition to inter and infra-specific competition.
It is postulated that larger and more dominant species will have a negative impact on the distribution and abundance of smaller rival species. This is evident when considering areas of overlap in the abundance and distribution of spotted and brown hyenas. Sightings of brown hyenas, which were once frequent and considered widespread across the reserve, now only occur in isolated cases along the Limpopo River with the majority of sightings along the Motloutse River.
In addition, it is also hypothesized that there is a remarkable difference between the abundance of these two carnivore species in the NTGR, compared to reserves immediately to the south of the Limpopo River. While the NTGR is considered to have a relative high density of spotted hyenas and a low density of brown hyenas, an inverse relationship is observed in these neighboring reserves. Historical records suggest that the density of large predators, especially spotted hyenas, were very low when the NTGR was first proclaimed a nature reserve in the mid 1960’s (McKenzie, 1990).
This could be ascribed to possible persecution of spotted hyenas in neighboring areas. Spotted hyenas take longer to recolonize an area where they were previously persecuted (Kruuk, 1972; Henschel, 1986; Smuts, 1982). This was evident in South Africa's Kruger National Park where culling operations was put in place to reduce lion and spotted hyena numbers in order to curb the decline of wildebeest and zebra populations. This was a misguided attempt and although lions recovered to their former numbers, spotted hyenas took more than a decade to achieve theirs.
In addition to obtaining reliable population and abundance estimates of spotted hyenas in the NTGR, we also aim to document their spatial-temporal movement and inter-and intra-competition with other large carnivores in the region.