Will Selfies, Electrocution and Deforestation Fast-track Sloths – the World’s Slowest Mammal – To Extinction?

8 mins

Can sniffer dogs, tracking backpacks and sloth crossings can keep these tree-living critters tucked safely away in the canopy where they belong. Words

Shaggy-furred, solitary and famously slow, the sight of a sloth hanging upside down is not only the stuff of memes. They spend 90 per cent of their lives upturned; eating, sleeping, mating and even giving birth!

Sloths may descend from an ancient superorder of mammals that evolved 65 million years ago, but these fuzzball’s future hangs precariously in the balance. Native to the lowland rainforests of Central and South America, their survival is entirely dependent on keeping their tropical forest home – which provides shelter, food and protection from predators – intact.

Tethered to the tree tops, a sloth will avoid the forest floor at all costs, retreating here just once a week for a single bathroom break, and risking their lives in doing so.

Deforestation due to agriculture, logging, ranching and urbanisation poses the single biggest threat to these nocturnal mammals. Tethered to the tree tops, a sloth will avoid the forest floor at all costs, retreating here just once a week for a single bathroom break, and risking their lives in doing so. Camouflaged in the canopy by their greenish matted hair – a microhabitat that hosts bugs, beetles and green algae – on the ground, they’re vulnerable to predators such as jaguars and dogs. Forced to crawl clumsily, here, sloths are completely out of their comfort zone, and also risk injury or fatal collisions with vehicles.

sloth clumsily walks on the forest floor
Forced to crawl clumsily, sloths are completely out of their comfort zone on the ground

 A study co-authored by primatologist-turned-slothologist Sam Trull reported that the two-fingered sloth is increasingly vulnerable to domestic dogs in Costa Rica, whose national symbol is, you guessed it… the sloth! On paper, Costa Rica may be the first tropical country in the world to have reversed deforestation, but there is mounting evidence that fragmentation of its precious forests is on the rise.

The Central American country is home to two of the world’s six species of sloth: Hoffmann’s two-toed and the Brown-throated three-toed, which is the commonest. They mainly populate its southern Osa Peninsula forests and the national park of Manuel Antonio: a resort destination in Costa Rica’s Central Pacific Region, where sloth habitat is gradually being gobbled up by palm oil plantations and unregulated ‘tree trimming.’

‘Some sloths – like recently weaned juvenile three-fingered – have really small home ranges amounting to just five trees. By removing one tree in that home range, you’re sentencing them to death by starvation’

Sam Trull, The Sloth Institute

‘Here in Manuel Antonio there’s a lot of microhabitat fragmentation where trees are trimmed for the view of the ocean,’ co-founder and director of Costa Rica’s The Sloth Institute (TSI) Sam Trull tells The Ethicalist. ‘They can’t jump at all! Even small gaps in the canopy can be a big problem for them,’ Trull says of sloths, who can find themselves isolated by just a couple of roads.

‘Some sloths – like recently weaned juvenile three-fingered – have really small home ranges amounting to just five trees. By removing one tree in that home range, you’re sentencing them to death by starvation,’ says Trull, since their diet is almost entirely made up of low-calorie leaves. Sloths extremely low metabolic rate means they move less than half the length of a football field in one day.

Multiple Enemies

Another major menace is electrocution from poorly insulated power lines. Trull says “sloths have poor vision and will always choose the path of least resistance,’ which in some cases will be a live wire. Sloths can also mistake electrical cables for tree vines. Those that survive the shock typically sustain life-changing third and fourth-degree burns, often resulting in the amputation of a limb, and / or organ failure.

sloth hangs from tree
Sloths are poor sighted and can mistake electrical cables for tree vines.

According to The Sloth Conservation Foundation, 50 per cent of the animals electrocuted in Costa Rica are sloths, with orphaned baby sloths often being collateral damage.

In a disturbing trend, baby sloths are preyed on not just by Harpy eagles, but illegal loggers too, some of whom sell them to unethical and exploitative tourist entertainment trades, where they’re used as props for tourist selfies.

Baby sloths are preyed on not just by Harpy eagles, but illegal loggers too, who sell them to unethical tourist entertainment trades, where they’re used as props for tourist selfies.

Contrary to their seemingly permanently smiling faces – a result of their mouths naturally turning up – these solitary mammals aren’t comfortable being cuddled, petted, groomed or bathed. Fuelled by sloths’ rising internet popularity, so-called harmless photo ops don’t just persist in petting zoos. In some regions of Costa Rica, it’s not uncommon to be offered a $10 sloth selfie at a tourist restaurant. Tragically, many of these arboreal-dwelling mammals struggle to survive beyond six months in captivity.

baby sloth with tourist
In some regions of Costa Rica, it’s not uncommon to be offered a $10 sloth selfie at a tourist restaurant. Tragically, many of these arboreal-dwelling mammals struggle to survive beyond six months in captivity.

Sloths can also be dangerous to people, if provoked, owing to their powerful jaws and claws.

‘Two-fingered sloths can be very aggressive [if threatened]. They can even break fingers!’ explains Trull.

Sloth Solutions

Thankfully, there are sloth solutions being developed and deployed by dedicated sloth conservationists. Designed to replicate tangled vines, ‘sloth speedways’ tether treeless areas, offering a safe route across cleared patches of jungle. ‘It may just be a simple rope, but it’s a strategically placed one!’ Trull says. These artificial canopy bridges – which run along the treeline as high as 50-metres in the air – are a lifeline to sloths, who are incapable of jumping from branch to branch. They also benefit other tree-dependent wildlife like monkeys, reptiles and raptors.

Founded in 2017 by British zoologist Dr. Rebecca Cliffe, The Sloth Conservation Foundation’s (SloCo) has its own sling-shotting tree-climbing team members who install sloth crossings as part of its Connecting Gardens Project in Costa Rica’s Limón province. Firing on all cylinders, SloCo also GPS collars wild sloths, rewilds patches of land with sloth-friendly trees and insulates power lines.

Technology and data collection also underscore the majority of SloCo’s conservation initiatives. This is largely thanks to Cliffe, whose ground-breaking research has put her at the forefront of global sloth science. Credited with conducting the very first population study of sloths, the 34-year-old carries out most of her fieldwork in Costa Rica’s Limón province. One of Cliffe’s biggest challenges has been fitting wild sloths with tiny wearable 3D-printed backpacks containing a microchip and data logger, which records everything from their temperature to the tree they’re munching on.

Sloths are feeling the strain of a warming planet more than most mammals, largely down to their slow metabolism, which makes it difficult for them to regulate their body temperature and risks pushing them to extinction by the end of the century.

Along with Keysha – the world’s first scat detection dog trained to sniff out sloth poop –SloCo are also slowly but surely building the first ever sloth population census.

Whilst this research is helping to support sloths ongoing conservation, it also lays bare an uncomfortable truth: the impact of climate change. Sloths are feeling the strain of a warming planet more than most mammals. A newly published study led by Cliffe reveals that this is largely down to sloths’ slow metabolism, which makes it difficult for them to regulate their body temperature. Worryingly, their unique physiology and slow-motion lifestyle risks pushing them to extinction by the end of the century.

Making its own valued contribution to global sloth science is The Sloth Institute (TSI): the first organisation to debunk the theory that sloths’ hand-raised by humans can’t be successfully released back into the wild. ‘We’ve [successfully] released one-armed and one-eyed sloths before and they all do really well,’ Trull tells me. One of TSI’s most recently released sloths, Elsa, is a heartening tale of triumph in the face of adversity. Trull personally hand-raised her after finding the baby sloth dangling from a vine in 2020 with partial paralysis of her hind legs. Despite never regaining full use of her legs and having misshapen hips, in February this year Elsa gave birth to a healthy baby named ‘Snowflake,’ Trull reveals.

Here’s hoping Snowflake will be as resilient as her mother, and be able to keep pace with a rapidly changing and warming home.

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