The endangered African wild dog was historically distributed throughout much of sub-Saharan Africa, but due to direct persecution and habitat loss, very few viable populations remain. Wild dogs have very large territories that range in size from 350 – 1000km2. In the southern African bushveld, territories in the region of 500 – 600km2 are more common. As a result of these extensive territories, wild dogs occur at low densities. Conserving this wide ranging species is thus very difficult, and requires very large protected area.
The only self-sustaining and viable wild dog population in South Africa occurs in the Greater Kruger National Park ecosystem. The remainder are scattered across the country in several smaller reserves that are fenced and geographically isolated. As a result, this precludes natural dispersal events (both emigration and immigration) that play a fundamental role in wild dog population dynamics. Consequently, intensive management is required to manage these meta populations, necessitating periodic translocations to supplement gene pools. This is difficult and not always successful.
The Northern Tuli Game Reserve (NTGR) in eastern Botswana is largely unfenced and borders South Africa and Zimbabwe. The reserve is scheduled to form part of the greater Shashe-Limpopo Transfrontier Conservation Area. Several dispersing wild dogs have been seen in the reserve over the past couple of years. Dispersing animals are usually single-gender groups that leave their natal packs in search of other wild dogs. They form a new pack with dogs of the opposite gender, and in this way mate with unrelated individuals. Since there has not been a resident pack of wild dogs on the NTGR for several decades, dispersing wild dogs merely move through the NTGR and do not become resident.
In November 2007, 18 wild dogs were moved to the NTGR and later released in April 2008. The overall goal of the project was to establish a resident pack on the reserve. Since dispersing dogs still pass through the reserve periodically, it is envisaged that a resident pack will facilitate the formation of new wild dog packs in the region. Since these would be free ranging packs, they would not necessitate the intensive management associated with South Africa’s meta-populations.
This conservation opportunity presents itself as a result of the open ecosystem (no fences). How could one then open the enclosure’s gates and merely expect a pack of wild dogs, capable of travelling hundreds of kilometres, to become resident on the reserve?
In natural free-ranging populations, packs have large yet well-defined territories. Boundaries are communicated to neighbours using urine and faecal markings. Dr J.W. “Tico” McNutt, director of the Botswana Predator Conservation Trust (BPCT), first noticed the long-lasting effects of these scent marks in 1996 when four of his ten study packs died after an outbreak of rabies. It took several months before neighbouring packs probed and later filled the territorial voids. This sparked the idea of using scent marks to limit the ranging behaviour of wild dogs.
Prior to the release of the pack on the NTGR, scent marks were collected from one of McNutt’s study packs, frozen, and flown down to the reserve. These were strategically placed towards the periphery of the reserve in an attempt to create artificial territories. We refer to this as the BioBoundary: a biologically relevant boundary. This novel experiment has had great success, with the pack still on the reserve more than a year after release. The dogs have successfully raised 12 pups and will shortly have second litter of pups.
What makes the achievements even more remarkable is the fact that the relocated pack was removed from Marakele National Park after repeatedly breaking through the perimeter fencing and moving into the neighbouring farming areas. Several dogs were in fact shot on one of these forays.
The second part of the BioBoundary experiment is underway at BPCT’s head office in Maun, northern Botswana. A laboratory has been set up and in an attempt to unravel the key volatile odorants found in the scent marks and that are responsible for communicating territoriality. This complex component of the project is headed up by Dr Peter Apps, and the project is still in the early stages of development. Should these compounds be identified, they can be produced synthetically, making the deployment of scent in the field far more feasible. This groundbreaking approach would have great significance for the management of not only wild dogs, but other carnivores and territorial species.