The 19th and 20th centuries saw a major decline in Arctic fox populations in Fennoscandia, the vast peninsula that includes Finland, Norway, Sweden and part of Russia. By the early 21st century, as few as 40 Arctic foxes (Vulpes lagopus) remained. But after a nearly two-decade-long captive-breeding and reintroduction program, that number has grown to approximately 500, leading to an easing of the species’ threatened status in Norway and Sweden.
Reintroductions of this kind offer hope in the fight against declining canid biodiversity across the globe. Yet these successes, too, remain precarious, as they take place against the background of a rapidly changing and nature-depleted world.
In a recent paper, researchers warn that the sustainability of the Arctic fox conservation program is potentially being undermined by climate change, which could be disrupting the life cycle of the lemming, the fox’s primary prey.
The Arctic fox’s survival is “problematic if lemmings are disappearing,” Arild Landa, a scientist with the Norwegian Institute for Nature Research, told Mongabay. “You might call the lemming the engine of the high alpine areas .… [But] lemming cycles have been interrupted during recent years and that is believed to be due to a warmer climate.”
Add to that a second climate conservation challenge, as the Arctic fox is displaced by the red fox (Vulpes vulpes), which is moving northward with warming temperatures, outcompeting V. lagopus for food, and occasionally preying upon the smaller species.
To help maintain the expanded but tenuous Arctic fox population, a costly supplementary feeding program — totaling 30,000 kilograms (66,100 pounds) of dry dog feed per year — has been instituted while “control” measures to limit red fox numbers are carried out.
These efforts have so far been successful in bringing the species back from the brink, Landa and his colleagues write. “However, anthropogenic drivers facilitating red fox invasion into the Arctic fox habitat, along with climate driven irregularities and dampened small rodent cycles, could inhibit the establishment of a self-sustained population.”
Canid species around the globe are likewise at risk, not only hit by one-two punches, but staggering under three or more blows, as they take a pummeling from threats on all sides. This onslaught has engaged researchers because the loss of these predators can seriously endanger ecosystem health, while improved canid conservation not only aids in improving habitat, but may even help curb climate change in some cases.
Climate change: Canid winners and losers
The world is in the midst of a massive, chaotic, human-caused wave of biodiversity loss, with some wild canid species swept toward destruction, while others see their status improve.
The Arctic fox is just one among 36 species within the Canidae family. Though its conservation status is considered of least concern globally, its precarious status in Fennoscandia is shared by five species now recognized as globally endangered by the IUCN: the African wild dog (Lycaon pictus), Ethiopian wolf (Canis simensis), North America’s red wolf (Canis rufus), Asia’s dhole (Cuon alpinus), and South America’s Darwin’s fox (Lycalopex fulvipes).
Climate change is one of the perils the world’s canid species must navigate — with varying projected outcomes. A modeling study using the worst-case global warming scenario suggests that generalist canid species, like the red fox, South America’s crab-eating fox (Cerdocyon thous), and the gray wolf (Canis lupus) could gain ground as climate change escalates. Other species, with “specific niche requirements,” could lose out, says Lucas Porto, the study’s lead author and an evolutionary ecologist at Brazil’s University of São Paulo. “Species that are going to decrease live in a very small part of the planet, and have specific prey,” he says.
According to Porto’s team, the maned wolf (Chrysocyon brachyurus) and hoary fox (Lycalopex vetulus), which both dwell in South America’s Cerrado savanna biome, are among those species likely to be threatened by climate change. Separate research indicates that the Ethiopian wolf could lose all its already limited habitat under every climate change scenario, likely beckoning its extinction in the wild. Still other studies find that higher temperatures could negatively influence mortality among African wild dogs by exacerbating existing threats and reducing their ability to reproduce.
Lost and fragmented habitat, diminishing prey
Climate change is just one of nine planetary boundaries that researchers say humanity cannot cross without seriously endangering life on Earth. Others, such as land-use change (bringing about habitat loss and increased human contact), plus threats to biosphere integrity (bringing about prey loss) are already directly impacting wild canids. Add to that the stress of increased disease and persecution by people.
Brazil’s Cerrado, a global biodiversity hotspot, is less well known than the Amazon, yet habitat reduction and fragmentation in this vast grassland has occurred at a far faster rate than in the neighboring rainforest. In 2020-21, the savanna saw its highest rate of loss recorded thus far.
Rapidly expanding agribusiness, coupled with the building of a huge road network and dams, has isolated some Cerrado maned wolf populations, causing them to show early signs of genetic separation, according to 2022 research. While this isolation isn’t currently high, or entirely unexpected, it could, “if it continues in this direction,” lead to “losing genetic diversity,” says study co-author Frederico Gemesio Lemos, from the Cerrado Mammals Conservation Program at the Federal University of Catalao.
Elsewhere, some tropical species, while currently having a lower threatened status, are increasingly stressed by habitat loss: The elusive short-eared dog (Atelocynus microtis), the Amazon’s only endemic wild canid, for example, is being forced to retreat all along the so-called Arc of Deforestation, which stretches across Brazil. A 2020 study suggested this canid could lose up to 30% of its distribution by 2027.
Habitat reductions also increase human contact, thereby heightening related dangers such as roadkills and overhunting. Across Asia, the endangered dhole, dubbed the Asiatic wild dog, has lost an estimated 75% of its former range, putting it in closer proximity to humans; in Southeast Asia, rampant snaring impacts the species indirectly via bycatch, while also reducing prey abundance.
A recent study identified northeastern Cambodia as a potential stronghold for the dhole, along with remaining wild locales in Myanmar, Thailand and Malaysia. “The key thing is to ensure that habitats are protected,” Pablo Sinovas, Cambodia country director with Fauna & Flora International, told Mongabay. Maintaining healthy prey populations is also essential, even as the serious threat of snaring decimates ungulates in some areas.
Declining canid prey is a recognized problem in Thailand too, says Nucharin Songsasen, head of the Center for Species Survival at the Smithsonian’s National Zoo & Conservation Biology Institute. In some cases, she notes, dwindling prey can precipitate a “domino effect” as pack hunters such as dholes leave their habitat in search of food, prey on livestock, and in turn prompt human-wildlife conflict and persecution.
“When the forest is empty, there’s nothing for them to eat, and then they might take out a whole herd of goats,” said Songsasen, who is also coordinator of the IUCN’s Dhole Working Group. “As people who study carnivores, we sometimes only focus on conserving carnivores. But now we need to start figuring out how we can maintain those prey populations [as well].”
In India, dholes are generally faring better than their counterparts in Southeast Asia, says Arjun Srivathsa, a fellow at the National Centre for Biological Sciences-TIFR, India. But in the country’s northeast, prey depletion is a major concern for all carnivores.
“Dholes are extremely habitat-sensitive,” Srivathsa wrote in an email. “In other landscapes of India, degradation and loss of habitat connectivity between designated protected areas threatens dhole populations through impeding dispersal and movement between populations.”
The threat of disease
Habitat fragmentation and the advance of agricultural frontiers brings people, livestock, domestic animals, and wildlife together, leading many conservationists to name disease as one of the most pressing threats to canid populations.
In 2017, an outbreak of canine distemper virus (CDV) heavily impacted the population of African wild dogs in Kenya’s Laikipia county, says Samuel Mutisya, head of conservation at the Ol Pejeta Conservancy. Prior to that outbreak, 20 or so wild dogs were known to roam the Ol Pejeta Reserve; today just one or two are seen, and rarely.
But identifying the extent of the disease threat, and guarding against it, is challenging, says Ezequiel Hidalgo, director of science and conservation at Buin Zoo in Chile. He notes that viruses, such as CDV, are among the most prevalent risks faced by Chile’s endangered Darwin’s fox. However, a 2020 study found no trace of CDV in foxes there, even though CDV has high prevalence among domestic and feral dogs sharing the same environment. Hidalgo offered two theories as to what might be going on: Either there is zero or limited contact between foxes and dogs, or Darwin’s foxes that contract it are dying in the wild without a trace. The latter, he says, is most likely.
Rabies, which kills around 59,000 people annually, is one of the greatest threats to remaining populations of the Ethiopian wolf. This species lives on wild “islands in a sea of [domestic and feral] dogs,” according to Claudio Sillero, founder and director of the Ethiopian Wolf Conservation Programme.
Since monitoring of the species began, conservationists have registered at least a dozen rabies outbreaks, with potentially devastating consequences for packs. Ethiopian wolves are also imperiled by agriculture’s continued intrusion into the species’ mountainous range, even as the impacts of climate change could “do away with” the wolves. The current priority is to address the most pressing threat: curbing disease to preserve the species for the immediate future, according to Sillero.
Are canid comebacks benefiting forests?
Efforts to address common canid threats regularly take place in the context of work to restore and rewild natural areas. For years, the archetypal example making the case for conserving often maligned canids has been found in Yellowstone National Park in the United States. Wolves were reintroduced there after a decades-long absence in 1995, and caused a much-debated tropic cascade that changed the forest ecosystem.
Extensive studies have been conducted to understand the wolves’ impact, revealing both direct and indirect effects. Researchers have connected the wolf comeback to increased diversity of tree cover, as the roving packs of canids reduced browsing elk, leading to a burst in tree growth among willow, aspen and alders — allowing plant expansion along riverbanks, thus improving streamside and aquatic habitat. In tandem, other animal species such as beavers returned, while wolf kills provided meals for a range of scavengers.
In Europe, wolves made a comeback of their own. Previously extirpated from much of Western Europe, populations migrated westward from the wilder east side of the continent.
In Poland, researchers are studying wolves in the Białowieża Primeval Forest to understand their impacts. For Dries Kuijper, with the Mammal Research Institute at the Polish Academy of Sciences, it comes down to the wolves’ influence on their prey: “You get some parts of the forest where red deer presence is much lower, and also their impact on the vegetation is much lower,” he said. “So, with the wolves in the forest, you get many places where trees can nicely grow. Whereas without the wolves, you would have much more impact of deer everywhere,” with heavy browse on plant species.
Research by Kuijper’s group indicates that wolves can strongly reduce deer browsing pressure by up to 25% in core wolf areas, depending on variable landscape factors.
“We know that the potential for [saplings] to grow and continue to grow increases [with wolf presence],” Kuijper said. How exactly this translates over the long term into adult tree growth in Białowieża, and thus potential carbon storage, remains an open question.
Evidence gathered by Kuijper’s team also suggests wolves bring “relatively subtle effects” to forest regeneration. “Wolves and other large carnivores can at least add something of the processes that we’ve lost. I think that’s the value, because if you get natural dynamics and natural processes back, biodiversity will profit.”
Researchers, including Oswald Schmitz, professor of population and community ecology at Yale University’s School of the Environment, underscore the integral role that wolves and other large carnivores play: “In order to really have sustainable and healthy ecosystems, we need the full complement of predators, herbivores, plants and microbes, living together,” Schmitz told Mongabay in an interview.
Research by Schmitz indicates that wolves can enhance the potential of boreal forests to take up and store carbon by controlling the abundance of prey species like moose. “If you do the scaling [up] across the entire boreal forest, [that total tree growth] can amount to as much as the equivalent of what Canada emits through fossil fuel burning,” he said. There are caveats, however, as similar carbon storage increases aren’t found in all ecosystems, such as grasslands, where wolves may suppress carbon storage capacity.
“We’re looking at nature-based solutions to try and offset human impacts. Just restoring and protecting wolves and moose and their interactions in the boreal ecosystem can actually lead to huge gains in the ability of these ecosystems to help us out in fighting the climate problem,” Schmitz concluded.
Bringing canids back: ‘Think big picture’
Approximately 9,000 kilometers (5,600 miles) south of Norway’s Arctic fox project, another successful reintroduction program is underway in Mozambique’s Gorongosa National Park. Endangered African wild dogs, along with many other large species, were wiped out there in the latter half of the 20th century.
But in 2018, a pack of 14 wild dogs was released. Today, the population numbers more than 100. That increase in predators helped restore a “landscape of fear” among prey species, explains Paola Bouley, who was part of the reintroduction team. And that’s proven to be a good thing for park ecology. “The population is doing so well and it feels like more of a balance,” Bouley, now with NATURA Moçambique, said in an interview.
How exactly the wild dogs will impact the wider ecosystem over time remains unclear, according to ecologist Robert Pringle at Princeton University, whose lab has studied Gorongosa extensively. Shifts in behavior and distribution of prey species such as bushbuck and reedbuck have been noted. But it’s difficult to credit that improvement exclusively to the wild dogs, he said.
“Our previous research indicated that the decimation of apex carnivores had cascading [negative] impacts on the ecosystem by relaxing constraints on habitat use by herbivores,” Pringle explained via email. “We know that losing the top carnivores causes shifts in herbivore behavior, herbivore abundance, and plant communities. [But] pinpointing the importance of wild dogs relative to other carnivore species such as leopards and hyenas is a work in progress.”
With the success of the Gorongosa reintroduction, conservationists are now looking past park boundaries to create corridors for wild dog movement across the surrounding landscape, and hope to link up the park’s wild dogs with an isolated population to the east.
“We’re really trying to think big picture; larger-scale connectivity and coexistence,” Bouley said. Part of the impetus is that common threats, like disease, still loom: “It [only] takes one bad encounter with a rabid dog in a community, and you could potentially wipe out populations of lions and dogs … The [initial reintroduction] success is very short term unless we begin to think much bigger.”
For Pringle, reintroductions of this kind “are one tool with which to fight biodiversity loss and ecological decay.” He also underlines the importance of providing footholds for endangered species such as the African wild dog, helping them survive and thrive: “That’s important to me. And more generally, the fact that it is possible to restore thriving biological communities gives me hope.”
Canid survival in a rapidly changing world
Experts now know that wild canid populations play a key and essential role in well-functioning ecosystems, acting as seed dispersers, rodent controllers, and herbivore managers. Though they face many planetary threats, efforts to conserve them could aid in ecosystem restoration, and potentially benefit the fight against climate change.
Though the challenges facing wild canids are manifold, Sillero, who is also chair of the IUCN’s Canid Specialist Group, is hopeful for their survival, noting that many canid species are resilient and can bounce back from losses. Broadly speaking, he says, they may be faring better across their biological family than others, such as wild felids.
But long-term canid survival requires conservation at a bigger scale, asserts FFI’s Sinovas: “If you’re thinking about recovery, then you need to think about the ecosystem as a whole … You need to think about the balance of predators and prey. Dholes, for example, can fill part of the ecological role of other species, such as tigers.”
In the case of the Arctic fox, that may mean broader human and natural solutions. Up until very recently, conservationists have employed “a single species approach,” Landa said. “In the future it will be more of a whole ecosystem approach [that’s needed], and I think that is the necessary thing to do.”
This article was originally published at Mongabay.
Banner image: Arild Landa, a researcher with the Norwegian Institute for Nature Research, says the long-term Arctic fox conservation effort is positive, but is concerned that climate change, lack of natural prey, and encroachment by the larger red fox could undermine its success in the long term. Image courtesy of Craig Jackson/NINA.
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