Camera traps completed one of the most thorough surveys of African rainforest yet

PNS Survey, Author provided

Mattia Bessone, Liverpool John Moores University and Barbara Fruth, Liverpool John Moores University

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.

Installing camera traps in Salonga National Park.
Jonas Abana Eriksson/PNS Survey, Author provided

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.

The grey-faced sengi (Rhynchocyon udzungwensis) was discovered by camera traps in Tanzania.
F Rovero/Wikipedia, CC BY-SA

Spotting stripes

Camera traps are becoming essential for documenting forest species, assessing their distribution and studying their behaviour, as well as counting what’s actually there.

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.

Big cats, like this African leopard (Panthera pardus), are among the simplest species to document with camera traps.
Haplochromis/Wikipedia, CC BY-SA

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.

A flagship species of Salonga National Park, bonobo populations are understudied in 70% of their range.
Christian Ziegler/LKBP, Author provided

What we found

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.

Nine of 43 species captured by camera traps in Salonga National Park, DRC.
PNS Survey, Author provided

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.

Mattia Bessone, PhD Researcher in Conservation Biology, Liverpool John Moores University and Barbara Fruth, Associate Professor, Liverpool John Moores University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Advertisement

Coronavirus: what the lockdown could mean for urban wildlife

‘Today, the pond. Tomorrow, the world!’
Patrick Robert Doyle/Unsplash, CC BY-SA

Becky Thomas, Royal Holloway

As quarantine measures take hold across the world, our towns and cities are falling silent. With most people indoors, the usual din of human voices and traffic is being replaced by an eerie, empty calm. The wildlife we share our concrete jungles with are noticing, and responding.

You’ve probably seen posts on social media about animals being more visible in urban centres. Animals that live in cities or on their outskirts are exploring the empty streets, like the Kashmiri goats in Llandudno, Wales. Others that would normally only venture out at night are becoming bolder and exploring during the daytime, like the wild boar in Barcelona, Spain.

Our new habits are altering the urban environment in ways that are likely to be both positive and negative for nature. So which species are likely to prosper and which are likely to struggle?

Hooray for hedgehogs

It’s important to note some species may be unaffected by the lockdown. As it coincides with spring in the northern hemisphere, trees will still bud and flower and frogs will continue to fill garden ponds with frog spawn. But other species will be noticing our absence.

The way we affect wildlife is complex, and some of the changes that we’ll see are hard to predict, but we can make some assumptions. In the UK, hedgehogs are our most popular mammal, but their numbers are in rapid decline. There are many reasons for this, but many die on roads after being hit by cars. With people being asked to only make essential journeys, we are already seeing reduced road traffic. Our spiny friends will have just emerged from hibernation and will no doubt be grateful for the change.

The lockdown could be well timed for hedgehogs emerging from hibernation.
Besarab Serhii/Shutterstock

Cities are also noisy places, and the noise affects how different species communicate with each other. Birds have to sing louder and at a higher pitch than their rural counterparts, which affects the perceived quality of their songs. With reduced traffic noise, we could see differences in how bats, birds and other animals communicate, perhaps offering better mating opportunities.

School closures may not be ideal for working parents, but many will use their time to connect with nature in their own backyard. More time spent in gardens (for those lucky enough to have one), perhaps doing activities like making bird feeders, could help encourage nature close to home. There’s been a surge in people taking part in citizen science projects like the Big Butterfly Count too. These help scientists to predict the population trends of different species. The British Trust for Ornithology has just made participation in their Garden BirdWatch Project free during the lockdown, so you can connect with wildlife and contribute to important scientific research.

---

Read more:
Living with rats involves understanding the city as an ecosystem

---

Desolation for ducks

All is not rosy for wildlife. Many species currently rely on food provided by humans. From primates fed by tourists in Thailand, to the ducks and geese at local parks which have been closed to the public, many animals may be seeking new sources of food.

In the UK, the bird breeding season has already begun for earlier breeders like robins. Depending on how long restrictions last, many birds could ultimately make bad decisions about where to breed, assuming their carefully chosen spot is always rarely disturbed. This could threaten rarer birds which breed in the UK, such as little terns, as dog walkers and other people flock to beaches once restrictions are lifted, potentially trampling and disturbing breeding pairs and their young.

A little tern sheltering eggs on an open beach.
BOONCHUAY PROMJIAM/Shutterstock

Dog walkers also enjoy lowland heathlands, especially those near urban areas such as Chobham Common in Surrey. These rare heaths are home to many rare bird species, like Dartford warblers, which could also see their nests disturbed once humans begin to emerge again in larger numbers. People who are enthralled by wildlife venturing into new areas during lockdown will need to carefully manage their return to the outdoors once restrictions are lifted.

Though some species may face challenges in now silent towns and cities, those species that live alongside us do so because they are so adaptable. They will find new sources of food, and will exploit new opportunities created in our absence. Hopefully this time will allow people to appreciate their local environments more, and find new ways to nurture them once all this is over.

Becky Thomas, Senior Teaching Fellow in Ecology, Royal Holloway

This article is republished from The Conversation under a Creative Commons license. Read the original article.