IntroductionThe African wild dog population in the Okavango Delta is one of three remaining strongholds of wild dogs globally, yet little is known about their movement patterns or how landscape features affect gene flow within this population.
The study will make use of new advances in GPS collar technology that allow for the study of animal movement at unprecedented scales, along with DNA samples that will help determine the genetic structure of the population across Delta. This will enable a better understanding of wild dog movement populations and gene flow to inform conservation efforts. Furthermore, the study will identify barriers in the landscape that limit gene flow and highlight important areas for mitigation by land managers.
Researcher: Briana AbrahmsCountry: Ngamiland District and Moremi Game Reserve, Botswana
Partner Organisation: Botswana Predator Conservation Trust
BackgroundThe Okavango Delta in northern Botswana supports some of the richest wildlife densities across Africa, including one of the largest populations of the Endangered African wild dog. The vulnerability of this species has been linked to its wide-ranging behaviour and large area requirements, yet we lack basic understanding of how landscape features affect their movement choices and ability to interbreed. This need is critical, as an animal’s ability to move through its landscape has fundamental consequences for both individuals and populations.
Recent research has relied either on GPS technology to understand short-term movement patterns, or genetic analysis to investigate how landscape features influence population gene flow, but financial or logistical constraints have prevented evaluation of the linkages between the two methodology paradigms.
This study provides a unique opportunity to unite both GPS and genetic data on African wild dogs to understand how landscape features shape two processes essential to the species’ survival: individual movement and population gene flow.
ObjectivesThere are four research objectives:
- Determine the current genetic structure of the Okavango Delta’s African wild dog population.
- Determine how environmental variables and anthropogenic landscape changes affect individual movements and gene flow.
- Identify natural and anthropogenic barriers within the study system that limit gene flow.
- Evaluate how individual movement is related to gene flow within the population.
MethodologyThe study is taking place in northern Botswana’s Okavango Delta, including the south-eastern portion of Moremi Game Reserve and surrounding Wildlife Management Areas. Research is being conducted out of Botswana Predator Conservation Trust’s (BPCT) field camp, located in Santawani, adjacent to Moremi Game Reserve.
Genetic data is being collected from DNA from blood samples taken when individuals are captured for collaring. A recent study has already genotyped DNA samples collected between 2000 and 2007 from 42 individual wild dogs in the study population, so these will be incorporated into this study. Added to this, BPCT has collected blood samples from nearly 50 more individuals in the population, which will be retrieved and genotyped using autosomal and Y chromosome microsatellite markers.
Clustering analysis in the computer programme STRUCTURE will be used to assess the overall genetic structure of the population and will determine any discrete genetic clustering in the population. To determine how environmental variables influence gene flow and identify any barriers within the study system, the study will also calculate pairwise genetic distances between all individuals.
Following established landscape genetics methods, landscape resistance values will be assigned to environmental covariates (e.g., habitat type, road density) and effective geographic distances between individuals will be calculated for candidate resistance surface models. By measuring the correlation between observed pairwise genetic distances and effective geographic distances, the study will evaluate which environmental variables most influence gene flow.
Custom-built GPS collars that have been deployed on 16 individual African wild dogs across seven packs as part of a collaborative study headed by BPCT. These collars are new to the study of animal movement in that they collection location data at extremely high resolution (up to one fix every 0.2 seconds) and they record activity data that be classified into discrete behaviour states. After ground-tracking the study animals, their collar data will be downloaded and used to determine how environmental variables and anthropogenic landscape changes affect movement. A case-control design using Step Selection Functions will be employed, allowing for the estimation of the relative probability of an animal selected a step by comparing the characteristics of observed steps with those in a set of available, but unused, steps. This will be compared with results from the genetic analyses described above.
The project has collected sufficient movement data on African wild dogs to analyse movement patterns and landscape connectivity for this species. A total of 22 individual wild dogs in 14 packs were fitted with custom-designed GPS radio collars provided by the University of London’s Royal Veterinary College. From the data, GPS locations could be paired with discrete behaviour states (resting, travelling and chasing) determined by acceleration data to quantify habitat use for the different behaviour. In total, the project collected 467 971 African wild dog GPS locations.
One of the findings was that African wild dogs have a much greater tolerance for high-risk human-dominated areas when dispersing. This implies that for the safe and successful dispersal that is essential for maintaining healthy populations, establishment of movement corridors through these areas must be paired with intensive carnivore-human conflict mitigation.
Results from this project were presented to a scientific audience at the 27th International Congress for Conservation Biology and are being drafted for publication in the peer-reviewed journal, Conservation Biology. Progress reports have been distributed to the Botswana Predator Conservation Trust and Botswana’s Ministry of Environment, Wildlife and Tourism.
To build local capacity, the project initiated an information and training exchange programme with Botswana’s Department of Wildlife and National Parks, pairing Botswana Predator Conservation Trust scientists with park officers to train them in wildlife management and science practices. The first stage took place in July, when two park officers were hosted at the field camp for a week for training on spoor survey collection. Further exchanges will take place on a quarterly basis and will focus on radio-telemetry skills and camera trap surveys.