Managed metapopulations

The managed metapopulation approach to Wild Dog conservation in South Africa has been adopted to complement the small, unmanaged Wild Dog populations in the Kruger National Park and in the Waterberg region in Limpopo Province.

The metapopulation concept:

A metapopulation is defined as a set of discrete, geographically isolated populations of the same species that may exchange individuals through dispersal, migration or, when implemented as a management strategy through human-controlled movement (Hanski et al. 1995, Hanski and Gilpin 1991). Implementation of such, human mediated, metapopulations becomes necessary when individuals no longer have the ability to move between isolated patches or to re-colonize empty patches (Akcakaya et al. 2007).
Much of the land that remains available for conservation forms a mosaic of patches that are too small to sustain viable populations and/or are isolated from each other. The conservation and management of small, fragmented populations has therefore become an unavoidable necessity. This phenomenon has forced wildlife managers to implement novel approaches to adequately conserve native species. In the case of wild dogs, even when they live in well-protected habitats with abundant prey, their naturally low population densities make them unusually susceptible to the combination of habitat fragmentation and random catastrophic events (Woodroffe and Ginsberg 1998).
In the South African wild dog managed metapopulation, individuals are moved between the reserves in an attempt to mimic natural dispersal patterns, to manage gene flow and maintain genetic integrity (Davies-Mostert et al. 2009). Both wild-caught and, to a lesser degree, captive-bred individuals were used to establish the initial metapopulation packs. Single-sex groups have subsequently been moved between reserves when it was necessary to promote new pack formation or maintain genetic integrity though healthy gene-flow.

 

Goal of the managed metapopulation

The goal of the wild dog metapopulation is, not only, to ensure the long term survival and conservation of the wild dog in South Africa but also to encourage biodiversity. Biodiversity is a broad concept incorporating compositional, structural and functional attributes at four levels of ecosystem organisation; namely landscapes, communities, species and genes. Of relevance to wild dogs in the metapopulation this incorporates not only the presence of wild dogs in an area, but, crucially, the restoration of their ability to interact with other species and to alter ecosystems.
What is important is the acceptance that ecosystems are dynamic and the willingness to allow natural processes to occur as far as possible. To try to manage against natural processes is ecologically and economically unwise. Management within managed metapopulation reserves should simulate the natural conditions for wild dogs as closely as possible. Natural fluctuations in numbers of individual dogs in each reserve, as well as in the metapopulation as a whole, are common and part of ecosystem functioning. Pack numbers is of more importance. The long-term viability of the wild dogs in each reserve should be the guiding principle. Their genetic integrity, reproductive activity and pack longevity are, thus, key features of their conservation. Guidelines for metapopulation management

These features highlight a number of important guidelines when considering the translocation of single-sex groups of dogs from one reserve to another, namely:

• When possible, translocate single-sex groups of dogs that have/are likely to naturally break away from their parental pack
• Translocation of individuals less than 18 months of age is not recommended (unless as a group with adult pack members)
• Managers should manage wild dogs at the pack level rather than the level of the individual
• It is important to realise that wild dog behaviour can be unpredictable and the conservation landscape of our country is dynamic thus requiring adaptive management to deal with population issues on a case to case basis, but based on the set principles of the metapopulation. For example, the unpredictability of dispersal events often occurs at times when no existing or new subpopulation can absorb groups. This explains why wild dogs must, on occasion, be placed in holding facilities until they can be translocated to a suitable site. Unfortunately the removal of dispersal groups means that natural pack formation within subpopulations is curbed and has to be reduced to a series of artificially bonded groups with little opportunity for individual choice.

Founder animal selection and captive breeding

The selection of founder animals was based on age, sex, immune and genetic status, as well as established hunting skills and previous exposure to competing carnivores (Mills et al. 1998). It was determined, using VORTEX models that animals could be captured from the wild in Kruger, Zimbabwe and Namibia in sufficient numbers to stock the subpopulations without jeopardizing source populations (Mills et al. 1998). A total of 66 founder individuals were used for initial metapopulation reintroductions. A high proportion of founders were wild-caught dogs, captured on private farmland where conflict with livestock and game farmers threatened their survival. Ten captive-bred animals were also used. These captive animals were bonded with wild-caught stock to improve aggregate hunting skills of reintroduced packs (Gusset, Slotow & Somers 2006). It is clear that the captive wild dog population does hold the potential to play a beneficial role in the metapopulation however due to the greater adaptability and likelihood of survival wild-caught wild dogs should always be given priority when placing individuals. It must be noted that if captive-bred individuals are used they should be bonded with wild-caught dogs to share experience gained knowledge on hunting and survival (Woodroffe 1997).

In July 2009 there were at least 168 known wild dogs in captivity in South Africa (numbers representing PAAZAB members only). A number of breeding centres have recognised the futility of maintaining or increasing numbers of captive individuals and have implemented contraception programmes to prevent individuals from breeding. WAG-SA recognises the potential value of the captive population but does not encourage continuous uncontrolled, unmonitored breeding of captive wild dogs or tolerate preference of captive wild dogs over wild caught dogs when placing individuals in reserves. In January 1998, two reserves already contained populations of reintroduced wild dogs, namely the 900 km2 Hluhluwe-iMfolozi Park in KwaZulu-Natal Province and the 600 km2 Madikwe Game Reserve in the Northwest Province. In June 2005 the wild dog numbers in the metapopulation were higher than in the Kruger National Park (264 individuals in 17 packs and 120 individuals in 15 packs respectively; Kemp and Mills 2005). In January 2011 the managed metapopulation comprised 182 individuals in 17 packs. In addition to translocations between subpopulations wild dogs were completely removed from metapopulation reserves on three occasions. One of two packs was removed from Pilanesberg National Park in 2005 to ‘’alleviate perceived predation pressure on ungulate populations’’, seven males were removed from Marakele Game Reserve in 2006, and the pack was removed from De Beers Venetia Limpopo Nature Reserve in 2010 due to predation pressure on prey populations incurred by both wild dogs and lions.

Apart from the loss of an entire pack to canine distemper in Tswalu Kalahari Reserve (G. van Dyk, pers. comm.) and through snaring in the case of Mkhuze Game Reserve, no other subpopulations have experienced extinction. "Management interventions staved off two other inevitable subpopulation extinctions at Tswalu and De Beers Venetia Limpopo Nature Reserve. The former occurred when supplementation with additional males was necessary after all the founding males in the second reintroduction were killed by lions in September 2006 (WAG-SA minutes, 2006). The latter involved the reintroduction of new adult females to Venetia four years after the population was first established, when the attrition of all unrelated founder adults rendered the pack unviable". By the end of 2006 the metapopulation had reached its goal of establishing at least nine packs of wild dogs well within the allotted 10 years.

Release site Province Release date(s) Current pack status
Balule Nature Reserve Limpopo 2005 3 packs
Zimanga Game Reserve KwaZulu-Natal 2009, 2011 * 1 pack
Hluhluwe-iMfolozi Park KwaZulu-Natal 1980/1981 (4×), 1986, 1997, 2001, 2003, 2007, 2008, 2011 * 8 packs
Karongwe Game Reserve Limpopo 2001, 2002 Absent 
Kgalagadi Transfrontier Park Northern Cape 1975 Absent 
Khamab Kalahari Reserve North West 2011 * 1 pack
Klaserie Game Reserve Limpopo 1991 Absent 
Kwandwe Private Game Reserve Eastern Cape 2004 Absent 
Madikwe Game Reserve North West 1995, 1998 (2×), 2000 * 2 packs
Marakele National Park Limpopo 2003 * Removed 
Pilanesberg National Park North West 1999, 2001 * 1 pack
Shambala Private Game Reserve Limpopo 2002 Absent 
Shamwari Game Reserve Eastern Cape 2003 Removed 
Tembe Elephant Park KwaZulu-Natal 2011 * 1 pack
Thanda Game Reserve KwaZulu-Natal 2004 * Removed
Tswalu Kalahari Reserve Northern Cape 2004 * 2013 1 pack
Mkhuze Game Reserve KwaZulu-Natal 2005, 2010, 2011 * 1 pack
Venetia Limpopo Nature Reserve Limpopo 1992, 2003 * Removed 

* Indicates populations which are currently, or previously were, included within the managed metapopulation