This story is part of Down to Earth, a Vox reporting initiative on the science, politics, and economics of the biodiversity crisis.
A decade ago, a team of salamander researchers made a dire prediction: that climate change would make much of southern Appalachia, a hot spot of salamander diversity, inhospitable to many of these sleek amphibians. Worst-case models for the region projected a “near-complete loss” of the entire group of salamanders they studied, known as plethodontids.
You’d certainly expect moisture-loving salamanders to be doomed in a warming world. Across the US, from North Dakota to Arizona, extreme droughts and heat waves are baking the landscape, drying up wetlands, streams, and other critical sources of water for humans and wildlife alike. And bad news for salamanders is bad news for the rest of us: These creatures are vital to ecosystems as predators and prey, and scientists see them as barometers of ecosystem health.
Yet in recent years, the slippery salamander has proven remarkably resilient to heat, drought, and perhaps even wildfires, owing to a number of unique adaptations. They can essentially shut down for months or even years at a time, and one species can ride out dry spells in a protective mucus sheath. Salamanders are teaching scientists about the power of adaptation and the limits of prediction.
To be clear, salamanders aren’t guaranteed a bright future. These small scamperers often like to stay hidden, making it difficult to collect good data — and one study from 2009 found “dramatic declines” in salamanders in Central America and Mexico. Meanwhile, more than 40 percent of the 200-plus species in North America are threatened with extinction, by some estimates. That has researchers worried.
But what these striking adaptations show is that climate change is complicated — it will impact different animals in different and unexpected ways. Creatures that appear especially sensitive, like salamanders, may be hardier than we think, muddying our predictions for the impacts of climate change on different ecosystems. And in some cases, extreme conditions may unlock behaviors that scientists haven’t noticed before.
To survive, salamanders do nothing
Salamanders look like lizards, which can survive in some of the world’s driest deserts, but the similarity isn’t even skin-deep. While lizards have dry, scaly skin, salamanders typically have to keep their skin moist, and some spend their entire lives in water. As amphibians, they’re cold-blooded, meaning they can’t regulate their temperature internally. All of these traits make climate change a concern.
Still, Eric Riddell, a salamander expert who’s now an assistant professor at Iowa State University, remembers questioning those predictions about the demise of salamanders. Salamanders have been around for millions of years, and at times the climate has been warmer than it is today, Riddell told Vox. Surely, he and some colleagues reasoned, these animals have evolved strategies to endure some of the conditions that global warming will unleash.
In the years since, Riddell and his colleagues tested their theory and found evidence to back it up. Certain salamanders, they discovered, have a remarkable ability to adjust their bodies to local conditions. When it’s hot and dry, for example, these amphibians can essentially shut down — lowering the rate at which they burn energy and lose water, he said, to the point where they hardly need to eat or drink anything to survive. “They are masters at doing absolutely nothing,” Riddell said.
During droughts, Riddell suspects that salamanders can shelter under the soil where it’s cooler and wetter — potentially for years at a time — only to emerge when conditions improve. Researchers also say salamanders can withstand wildfires using similar sheltering strategies (though their tolerance appears to vary by habitat). In other words, they can simply ride out poor environmental conditions, at least for a time.
Mucus cocoons and total transformation
There are other, more bizarre tricks that salamanders use to avoid drying out. The most delightful may be wrapping themselves in a cocoon made of mucus. (Who among us hasn’t wanted to curl up in a mucus cocoon at one point or another?)
That’s the strategy of a type of salamander called the lesser siren. To avoid desiccation when its habitat (typically a pond) dries out, the salamander buries itself and secretes mucus from its skin, which hardens to form a “parchment-like” cocoon. The cocoon can prevent dehydration for “at least 35 weeks,” or until the pond fills back up, according to a study from 1972.
Red-spotted newts, also a type of salamander, take an even more drastic approach in times of drought. Typically, they have three life stages after emerging from an egg: larval, when they’re aquatic; juvenile, when they live on land; and adult, when they return to the water. But when their habitat dries out, they can actually transition a fourth time, back into a terrestrial form, according to Steven Price, an associate professor at the University of Kentucky.
To make this move, the newts change the shape of their tail, the texture of their skin, and even their color. “It’s a really cool strategy for these animals,” Price said, and it helps them respond to unpredictable climate changes.
What salamanders can teach us about climate change
Taken together, these adaptations — especially the flexibility around energy use and water loss — may help salamanders better withstand some of the effects of climate change, according to Riddell’s work. “By integrating this flexibility into predictions, we found that salamanders could maintain their ability to reproduce, even under one of the worst-case warming scenarios,” he said.
So does that mean those salamander doomsday projections from 2010 are wrong?
The answer is probably yes, according to one of the scientists who first made them. “We’re not seeing these predictions holding true,” said Joseph Milanovich, the lead author of the 2010 study and an assistant professor at Loyola University in Chicago.
Milanovich spoke in the Smoky Mountains, where he was sampling the salamander population. He has yet to publish all of the results, but anecdotally, he says the salamander populations and distributions seem stable compared to 2012 data. “The physiological tolerance of a lot of these salamander species is higher than we thought,” he said. “They’re built for this.”
There is, of course, a limit to what salamanders can tolerate, said William Peterman, another co-author of the 2010 study and an associate professor at The Ohio State University. A severe drought that extends for years, for example, could do serious damage to salamander populations, especially considering that many species require water to reproduce. (Some research has already indicated that drought harms aquatic larval-stage salamanders.)
Similarly, more intense wildfires that burn extremely hot and over huge areas — which are likely to become more common under climate change — could be a problem, according to Milanovich and Peterman. “When fires get really intense they can burn all the organic matter” that salamanders burrow into, Peterman said. “Where we saw that happen, salamanders have virtually disappeared from the landscape.”
It’s also worth noting that our climate is warming much faster today, due to human-caused greenhouse gas emissions, than it did in the past — about 10 times faster compared to the average warming following historic ice ages. That means salamanders and other species in epochs past had a lot more time to adapt to the changes.
But ultimately, the story of salamanders may be a spot of good news, suggesting there are fewer threats to some animals than we once thought. “There’s an ability among wildlife to cope with these conditions beyond what we understand,” said Jennifer Hunter, resident director of the Hastings Natural History Reservation, a field station in northern California that’s part of UC Berkeley.
Last year, wildfires burned about a quarter of the Hastings reserve, which is 30 miles southeast of Monterey, but the resident plant and animal life quickly recovered, she said. “You are immediately seeing some of these species that should really struggle to escape — you know, small mammals, things like that — crop up really quickly,” she said. “We just think, ‘How did these little guys make it?’” Up to a point, nature can be highly resilient.
As for salamanders, researchers are holding out some hope that these charismatic crawlers will persist, despite the rapidly changing environments around them. The question, Riddell says, is, “Where can they hold on, and for how long?”
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