Aardvarks are notoriously elusive, nocturnal mammals. They generally hide in their underground burrows during the day and emerge at night to feed exclusively on ants and termites. Aardvarks are widespread throughout most habitats of Africa south of the Sahara, except deserts. But their actual numbers are not known because they’re so elusive.
Aardvarks top the bucket list of many wildlife enthusiasts, but few have been fortunate enough to see them – until recently. Daytime sightings of aardvarks are becoming more common in the drier parts of southern Africa. But seeing them in the daytime does not bode well because it indicates they might not be finding enough food.
To understand how aardvarks cope with hot and dry conditions, we studied them in the Kalahari, one of the hottest and driest savannah regions in southern Africa in which aardvarks occur. Our study took place at Tswalu, a private reserve in South Africa that supports research through the Tswalu Foundation. We equipped wild, free-living aardvarks with biologgers (minicomputers) that remotely and continuously recorded their body temperature (an indicator of well-being in large mammals), and their activity. Each aardvark also received a radio-tracking device, allowing us to locate them regularly. Tracking the aardvarks provided clues on how they changed their behaviour in relation to environmental stressors in the different seasons and years of our three-year study.
Our study found that in drought periods, aardvarks struggled to find food. It was difficult for them to maintain their energy balance and stay warm during the cool night, so they shifted their active time to the day. Some died from starvation. Given the aardvark’s importance to ecosystems, these findings are a concern.
No other mammal in Africa digs as many large burrows as the aardvark. Dozens of mammals, birds and reptiles use aardvark burrows as shelter from extreme heat and cold, protection from predators, or a place to raise their young. In many of South Africa’s conservation areas, temperatures have already risen by 2℃ over the past 50 years. Further warming by 4-6℃ by the end of the century has been projected.
With deserts and drylands expanding across much of Africa, climate change might threaten the aardvark itself as well as the many animals reliant on aardvark burrows as a cool shelter from rising temperatures.
During typical years, aardvarks were active at night and were able to regulate their body temperature between 35-37℃.
However, this pattern changed during two severe summer droughts that occurred in the Kalahari during our study. During the droughts, aardvarks shifted their activity to the daytime and their body temperature plummeted below 30°C.
Using remotely-sensed vegetation data recorded by NASA satellites and our own camera trap footage and logger data, we showed that these dramatic changes in body temperature and activity of aardvarks were related to the availability of grass, on which their ant and termite prey rely. When grass was scarce during droughts, the ant and termite prey became inaccessible to aardvarks, preventing them from meeting their daily energy requirements. As their body reserves declined, aardvarks were unable to sustain the energy costs of maintaining warm and stable body temperatures and shifted their activity to the warmer daytime.
Shifting activity to the warmer daytime while food is scarce can save energy that would otherwise be spent on staying warm during cold nights. But, for our aardvarks, even these energy savings were insufficient during drought, when the ground was bare and the ant and termite prey inaccessible. As a result, seven of our twelve study aardvarks and many others died, presumably from starvation.
On the Red List of Species of the International Union for Conservation of Nature, aardvarks are currently categorised as a species of “Least Concern”. However, we consider aardvarks to be threatened in the drier parts of their distribution in Africa, such as the Kalahari, where climate change brings about droughts. Disappearance of aardvarks from these ecosystems could have devastating consequences for the many other animals that rely on the aardvarks’ burrows.
We hope that our findings will raise further awareness about the consequences of climate change and inform future wildlife conservation and management decisions. Such steps might include assessments of the actual population status of aardvarks across Africa, or mitigation measures to preserve species that depend on burrows for refuge in regions where aardvarks might go locally extinct. More extensive measures, like water-wise reserve management, increasing sizes and connectivity of nature reserves in semi-arid regions, and reducing emissions to mitigate climate change, are just as urgent.
Finally, any solution to the plight of climate change on free-living animals requires a better understanding of their capacities to cope with drought. Therefore, many more long-term comprehensive studies are needed on the physiology and behaviour of the vulnerable animals living in hot, arid regions of the world.
Nora Marie Weyer’s disclosure statement has been updated.
Snakes are a diverse lineage of reptiles that are found on every continent except Antarctica. Despite differences in appearance, habitat preference, defence tactics and underlying biology, one thing is common to all 3,800 species of snakes — every last one is a predator.
As predators, snakes are likely to fulfil important roles in ecosystems. Knowing what snakes eat can help scientists better understand ecological connections among snakes and other species. This will lead to a better understanding of how ecosystems function and how ecological communities might be affected by changes in habitat or climate.
Some snake species have also evolved potent venoms which aid in subduing prey. Mounting evidence suggests venom composition is adaptive and linked to what snakes eat. Although snake venoms have evolved primarily for feeding, venomous snakes also bite defensively.
Incidents of snake bites on people prompted the World Health Organisation to declare snakebite a neglected tropical disease in 2017. Given the link between venom biochemistry and feeding, a detailed understanding of a species’ diet can inform research dedicated to mitigating the effects of snakebite.
Unfortunately, the details of many African snake diets remain a mystery. Historically, information on snake diets has come from dissecting preserved museum specimens or fortuitous observations of snake feeding that are published as brief notes in journals or newsletters.
More recently, methods for studying snake feeding habits have embraced technology. These include fixed videography studies of ambush predators like puff adders and timber rattlesnakes, as well as DNA analysis of faecal material from smooth snakes. But these approaches cannot be used for many snake species, and they require a significant amount of time, effort, and resources.
Snake diets can be difficult to study, so, in 2015 we realised that photographs and videos of snakes feeding were being shared regularly on Facebook. We set out to gather these observations using a dedicated Facebook group – Predation Records – Reptiles and Frogs (Sub-Saharan Africa) – and to record the shared observations systematically. Our findings showcase how the network of active users on Facebook can help us to collect ecological data quickly and cheaply.
After several years of community participation in our study, we turned more than 1,900 observations of reptiles or amphibians eating or being eaten into scientific data. Our database includes 83 families of predators and 129 families of prey.
For snakes, we gathered more than 1,100 feeding records. We soon saw that social media had helped gather these feeding records faster than ever before. The data collected from Facebook represent 27% of scientifically documented snake feeding records in southern Africa. More than 70% of all feeding records had not been recorded previously in the scientific literature.
To find out how data from social media compared to data collected using other platforms, we used iNaturalist (a popular citizen science platform) and Google Images to find observations of feeding snakes. Facebook outperformed both platforms in terms of the overall number of observations collected.
Finally, we noticed that observations collected from the different platforms produced different prey profiles, suggesting that certain prey may be over – or underrepresented in studies depending on the source of the observation.
Nearly all methods used for studying snake diets have biases. This may be why there are striking difference between what social media and the existing scientific literature revealed.
Facebook also let us identify prey more precisely. Most of the prey was photographed while being eaten or after regurgitation. On the other hand, prey collected from the stomachs of museum specimens are often partially digested, making the identification process difficult.
Our findings highlight the remarkable power of citizen science to reveal undocumented details about the natural world. In the case of snake diets, specifically, it is the harnessing of thousands of social media users that facilitated the data collection.
This is mainly because snakes feed secretively and relatively infrequently in the wild. But social media and the widespread use of smartphones with cameras means that even difficult to observe events can now be recorded in large numbers and across different geographic areas.
The continued detection of new feeding interactions shows how there is much to be learned about these remarkable animals. As more observations are made, the full picture of a species’ diet will be revealed. By using a community of observers, more data and information can be gathered for little to no cost.
While our study was restricted to southern Africa, expanding data collection efforts like this into the rest of Africa is necessary. Given that Africa experiences some of the world’s heaviest snakebite burden, details on the biology of its snakes will prove useful. If ever there was an opportunity to gather novel, important ecological information about snakes in Africa, this is it.
Globally, there are hundreds of groups on Facebook – some of which have close to 200,000 members – dedicated to sharing original photographs and observations of snakes. More generally, Facebook groups exist for most classes of animals and plants, and these communities have unprecedented observational power for researchers asking appropriate questions of the natural world.
Bryan Maritz, Senior Lecturer, Biodiversity and Conservation Biology, University of the Western Cape and Robin Maritz, Research fellow, Biodiversity and Conservation Biology, University of the Western Cape
Jellyfish can be found in almost every ocean in the world. These beautiful, graceful creatures are a sight to behold; their swift, pulsating motions gently propel them through the water. But the scene can quickly turn ominous as the animal transforms into a ferocious, formidable predator.
These creatures have no special organs for respiration or excretion. They have no head, no brain, no skeleton and no true circulatory system. This allows them to be highly adaptable and to survive in even the harshest conditions.
Most species typically have a multi-phase life cycle. Many jellyfish can exist as polyps on the sea floor, able to create identical clones of themselves. When conditions are just right, polyps are able to release numerous juvenile jellies into the water. Many polyps may even lie dormant when conditions are not favourable, emerging again when they improve. The free-swimming adult jellyfish often eat a variety of marine species from tiny shrimp to small pelagic fish. Many even eat other jellies. The adult jelly can also shrink when food is not available to conserve energy and resources, growing back to its normal size when food becomes available again. This unique life history gives them many advantages over other species.
Jellyfish are also well known for forming large swarms known as “blooms” – which can have far reaching negative effects. Jellyfish blooms have clogged the cooling intakes of power plants, resulting in total shutdowns; they can destroy fishing nets and spoil catches. Many species also deliver a painful sting that many beach-goers may know well.
But despite some of these negative impacts, jellyfish are incredibly useful. They are indicators of oceanic circulation patterns, play a rather large role in the mixing of oceanic nutrients and also help control pelagic fish populations (those that inhabit the water column, not near the bottom or the shore). It was recently discovered that jellyfish even provide microhabitats where other marine species may live and survive.
Jellyfish have also recently become the focus of a number of biotechnology and pharmaceutical studies as they appear to possess many properties that may be useful in a variety of applications, from household cleaning products to fertilisers. Other species are now commercially farmed for human consumption, with large fisheries already established in countries like India and China. Jellyfish are being turned into products like dehydrated chips, protein shakes and other food stuffs.
However, with few dedicated research efforts, jellyfish remain unexplored in many oceans and it is likely that many species have gone unrecorded or unnoticed. Some scientists even suggest that their numbers may be declining in some parts of the world. Global longterm data simply doesn’t exist for jellyfish, so scientists struggle to predict, track and mitigate their potential effects – good and bad.
But collecting the necessary data requires significant resources, manpower and expertise. That’s where a South African-led team of researchers based at the University of the Western Cape’s Department of Biodiversity and Conservation Biology comes in. Using samples collected by a global research vessel, we’ve been able to begin to establish a baseline of data for African jellyfish species. This, we hope, will allow us to establish more thorough trends across oceans, uncover new species (we’ve already identified one) and better understand the links between different species.
In 2016, we approached the Food and Agriculture Organisation’s EAF-NANSEN Programme to see whether jellyfish samples could be collected by its Dr Fridtjof Nansen research vessel. EAF-NANSEN agreed, and started collecting samples in waters across the African continent.
The first specimens arrived at UWC late in 2017 and we got to work. Jellyfish have few identifying features and a highly variable body type. So figuring out which species we had in the lab was no easy task. The team typically measures anywhere from 35 to 70 morphological features for any given species, which are then analysed statistically for patterns. DNA is also extracted from various individuals and populations to help identify species and to establish patterns of gene flow across populations.
So, what have we learned? First, it became clear early on that the African coastline encompasses a larger variety of species than previously thought. Our group has already found a new compass jelly off the southern coast of South Africa, along with a new species of rhizostome jellyfish that appears to be completely endemic to South Africa through some of our previous research.
Second, the team has begun to identify a number of other African morphotypes that appear to be distinct from their global counterparts. The species found here appear to show high levels of endemism, meaning they are changing in their physical appearance and even their DNA to adapt to our waters.
The work is continuing and we have already received three years’ worth of specimens and associated data which we hope to analyse alongside other African jelly experts.
The aim of this work is to build up and establish high quality resources for African jellyfish species that may be used to contribute to global studies and reviews. Eventually, we hope to establish population patterns across the east and west African coastlines; at the moment these data simply don’t exist. This will require a coordinated global effort, but as we’ve shown through our collaboration with the NANSEN programme, this is possible and it’s yielding great results.
African lions are one of the world’s favourite animals. But their numbers have been shrinking over the past century, especially over the past 30 years. Some scientists estimate that their numbers have halved since 1994.
Estimates of the total population of Africa’s king of beasts vary, but a recent CITES report suggested that only about 25,000 remain in the wild, across 102 populations in Africa. But the numbers in this report aren’t particularly reliable. Most used traditional survey approaches – like counts of lion footprints, audio lure surveys or expert opinion – and many were not peer-reviewed.
These traditional methods of counting lions produce highly uncertain estimates. A count of lions using their footprints may give you an estimate of, say, 50 lions in an area. But the uncertainty around this estimate could be between 15 and 100 individuals. This large uncertainty makes tracking how lion populations change from year to year nearly impossible. Our recent review shows that the majority of methods used to count African and Asiatic lions use these less robust methods.
Making sure that lion numbers are accurate and reasonably precise is key for the species’ conservation. Estimates of lion numbers underpin their classification as ‘vulnerable’. They also form the backbone for controversial management practices like the setting of trophy hunting quotas.
The good news is that better ways of counting lions are being developed. So called spatially explicit capture-recapture methods are useful for conservation because they tell us not only how many animals live in an area, but how they move in a landscape, what their sex ratios are and even where their highest numbers are located. This method has been used to count tigers, leopards, jaguars and mountain lions for over a decade but it is only now becoming popular for lions.
Spatially explicit capture-recapture methods use a mathematical model which incorporates the individual identity of animals (usually from photographs of natural body markings, spot patterns or even whisker spots) and their location in a landscape. By identifying and “marking” individuals over a period of time an estimate can be made of the total number of animals that live in an area.
This method was first used to count lions in a 2014 study in Kenya’s Maasai Mara. The lead authors capitalised on a historic way of identifying lions: their whiskers. Every lion in the wild has a unique whisker spot pattern, very much like a human fingerprint.
Recently, some of us applied this technique in a count of African lions in southwestern Uganda, in a region known as the Queen Elizabeth Conservation Area. These lions are interesting because they have a rare culture of tree-climbing. This means they have great local tourism value as each lion raises about USD$ 14 000 annually in park fees.
The status of lions in Uganda was not previously very well understood. After a wave of intense poaching during the unstable Idi Amin and Milton Obote regimes – 1971 to 1985 – during which time wildlife numbers plummeted.
But recent aerial surveys and radio-collaring studies suggested that lion prey numbers were recovering. A radio collaring study of lions from 2006 to 2010 also showed that lion home range sizes were small, and because range size is predicted by abundant prey, this suggested lions here were in good health.
From October 2017 to February 2018 we drove more than 8 000 km in 93 days searching for lions in the Queen Elizabeth Conservation Area. We obtained 165 lion detections. Using individual identifications from photos, we calculated that on average one could expect to find about 3 individual lions per 100 square kilometres, with a total of 71 lions in the entire area.
We used the spatially explicit capture-recapture method to assess how lion movements had changed from the home range study performed a decade earlier. Worryingly, our results showed that lions had increased their ranges significantly in just 10 years – above 400% for male lions and above 100% for females.
Also, there was only one female for every male in the wild. This is very different to other African lion populations which have a much higher proportion of females relative to males (about two females for every male).
From the standpoint of lion conservation and recovery these results are concerning. But, on a positive note, this finding has provided a timely alert. And we recommend the use of this relatively novel survey methodology to assess other lion populations across Africa.
More recently, in 2020, another rigorous study at Lake Nakuru National Park, Kenya, applied this approach and found that this method estimated lion population size to be about a sixth of what was previously thought. The Kenya Wildlife Service, in collaboration with local partners is now using spatially explicit capture-recapture in an ambitious nationwide survey of lions and other large carnivores at all potential strongholds across Kenya.
More broadly, these results further bolster the view that by relying on ad hoc, indirect methods to detect lion population trends, we may end up with misleading answers and fail to direct scarce conservation resources optimally.
We argue that all stakeholders involved in lion conservation across Africa and Asia should use rigorous survey methods to keep track of lion populations. These results should then form appropriate baselines for continent-wide reports on lion abundance, and help inform strategies aimed at their recovery.
Alexander Richard Braczkowski, Research Associate, Griffith University; Duan Biggs, Senior Research Fellow Social-Ecological Systems & Resilience, Griffith University; James R. Allan, Postdoctoral research fellow, University of Amsterdam, and Martine Maron, ARC Future Fellow and Professor of Environmental Management, The University of Queensland
Tropical rainforests are the world’s richest land habitats for biodiversity, harbouring stunning numbers of plant and animal species. The Amazon and the Congo basins, together with Asian rainforests, represent only 6% of Earth’s land surface, and yet more than 50% of global biodiversity can be found under their shade.
But observing even the most conspicuous species, such as elephants and apes, is still an extraordinarily difficult task. That’s not even mentioning all the secretive species that are protected by thick vegetation or darkness.
Camera traps have led a technological revolution in wildlife research, making it possible to study species without humans needing to be present. They can be left in the depths of a forest for weeks, taking pictures of anything that moves at any time of day or night.
From their advent three decades ago, camera traps have allowed scientists to discover species such as the grey-faced sengi – a new species of giant elephant shrew living in Tanzania – and the Annamite striped rabbit in Vietnam. They revealed that lions still wander the Bateke plateau in Gabon, ending speculation that they were locally extinct. They also photographed the offspring of the elusive Javan rhino, which scientists had thought had stopped breeding. With fewer than 100 individuals left, this gave hope that the species could be saved from extinction.
This latter measure, called animal abundance, is perhaps the most important information in wildlife conservation, as it allows researchers to assess the conservation status of a species. But until recently, camera traps could only be used to reliably estimate the abundance of animals with conspicuous markings, such as big cats with spots or stripes peculiar to single individuals.
Counting animals with camera traps remained impossible for the majority of species that lacked these conspicuous features, as the same individual could be counted twice by different cameras at different times. Methods that account for how animals move in and use their habitat were developed to help overcome the problem of detecting the same individual at different locations.
Another method, called camera trap distance sampling achieves the same result using a different approach. It subdivides the time cameras are active into “snapshots”, taking pictures at, for example, every fifth second in an hour. At a determined moment, an individual can only be spotted at one location, not elsewhere. Double counts are avoided, and researchers get the number of animals within the area surveyed by the cameras at a given snapshot.
We tested this new method in one of the most remote areas of the planet – the southern part of Salonga National Park, a world heritage site in the Democratic Republic of the Congo. Here, rangers only had data on the park’s two flagship species – the forest elephant and the bonobo. Near to nothing was known about the other animals that were more difficult to track.
Five field teams walked a forest the size of Wales to deploy 160 camera traps in 743 places. This unprecedented effort produced more than 16,000 video clips, totalling 170 hours of animal footage and revealing 43 different animal species, including bonobos and elephants.
We also captured species rarely detected by human observers, such as the giant ground pangolin, threatened by extinction, the cusimanses, a genus of social mongooses, and the stunning Congo peafowl, a vulnerable species that’s endemic to the country.
Where so far conservation of elusive species such as the African golden cat, the endemic Allen’s swamp monkey and another elephant shrew, the four-toed sengi, had to be based on little to no data, we’re now able to estimate their abundance in the wild.
For some species, the news from our findings were good. Our study revealed that the southern part of Salonga National Park alone harboured as many peafowls as were previously thought to be present in the whole country.
For other species, the results confirmed the need for greater protection. The 17,000 km² large and intact primary rain forest contains fewer than 1,000 giant pangolins. An alarming figure given the current illegal trade of pangolin scales.
As the technology and methods of camera trap surveys improve, they’re becoming capable of monitoring a diverse range of wildlife, from the tiny elephant shrew to the mighty forest elephant. This gives an insight into the complex and delicate equilibrium of the rainforest community and the threats to its survival.