Small carnivores are ecologically important species and key indicators of environmental change. However, for many of these species, we lack robust information on their conservation status, geographic distribution, and tolerance to anthropogenic threats. In this post, researchers from Nelson Mandela University share their experience with an emerging camera trapping method aimed at improving monitoring efforts for African small carnivores.
For a wide array of species, camera trapping has become a key tool for conservation research, often allowing researchers and practitioners to monitor cryptic species that are rarely observed. However, for small carnivores, camera trapping remains challenging – particularly for the smallest among them (< 3 kg), whose small body size and rapid movements make them difficult to capture on conventional camera traps. These challenges are often compounded by broader sampling objectives, as camera traps are frequently set to monitor wider biodiversity and/or focus on larger carnivore species. This typically results in camera traps being positioned at heights that may miss smaller-bodied species or placed in areas that may be selected by other species but less optimal for detecting smaller carnivores.
Researchers in Europe developed a novel camera trapping method to overcome these difficulties – the Mostela. A modified box design with a tunnel running through it and a camera trap placed inside. The Mostela has been found to improve detection rates for weasels and stoats, and the number of studies using this approach is increasing in Europe. Further studies in South America and Asia have shown it has promise for studying other small carnivore and rodent species. However, the Mostela had never been tested in Africa, despite the continent’s broad diversity of small carnivore species.
We were inspired by efforts to monitor small carnivore populations in Europe and believed the Mostela could be adapted as a monitoring device for a range of African small carnivores – particularly genets, mongooses and the African striped weasel. Since the original Mostela specifications were tailored for smaller European carnivores, we modified our Mostela boxes to be taller, longer, and wider. We then designed a paired station experiment, where each sampling unit included both a ‘regular’ camera trap and a Mostela box at each station, and conducted seven surveys across the Garden Route region of South Africa. These surveys ranged in length from 20 to 35 days and were conducted across multiple land uses (designated conservation areas, mixed-use areas, plantation woodlands). Our surveys resulted in 77 paired stations from which we could compare the number of species detected, the rate at which they were detected and, using occupancy models, quantify the probability of detection and number of survey days required per method whilst accounting for imperfect detection.
Our tests showed that the Mostela could become an important monitoring tool for African small carnivore species. Compared to conventional camera traps, the Mostela detected two additional small carnivore species (meerkat and striped polecat), improved daily detection probabilities, increased the number of photographic detections, detected small carnivore species at more sites, and required fewer sampling days to confirm small carnivore presence. On average, across species groups, seasons, and treatments, a Mostela increased daily detection probability by 217%.
When we consider the limitations of conventional camera trapping for small carnivores, our findings suggest that the Mostela can overcome several of these challenges. First, the detection field of a Mostela is much smaller, so if a small carnivore passes in front of the camera inside the device it is much more likely to be detected. Second, because the animal must enter the Mostela, it tends to move more slowly than it would along a game trail or road – this slower movement increases the likelihood of a successful capture. Third, the Mostela’s camera is not restricted by vegetation or other obstructions that typically limit the field of view. As most researchers know, a common issue when camera trapping is a rogue blade of grass or branch that constantly triggers your camera – but this isn’t a problem inside the Mostela and means it can be deployed in areas that may be challenging for conventional camera trapping. However, that’s not to say the Mostela is ‘problem free’. There are some age-old camera trapping problems that cannot be avoided – like elephants taking offence to your equipment… and it seems the Mostela is no exception!
Our findings show that the Mostela is an effective, non-invasive tool, offering higher detection probabilities, quicker species detection, and increased photographic capture rates. We also found that the Mostela was effective for sampling small mammal species, so holds promise for investigating predator-prey dynamics. Given the range of species we detected using the Mostela, and the high diversity of small carnivores weighing < 3 kg across Africa, we believe it could be a valuable tool for monitoring up to 50 species at the continental scale. Achieving this, however, will require extensive further testing across a range of habitats and species. We believe it is time for a more species-specific camera trapping tool tailored for monitoring African small carnivores and we are hopeful that the Mostela can contribute to this effort.
Read the full article ‘Using a recently developed camera trapping method to improve monitoring efforts for African small carnivore species’ in Ecological Solutions and Evidence.
Author: Rob Davis (X: @RobDavis1104; Blue Sky: @robdavis1104.bsky.social)
