Imagine thousands of pounds of salamanders per square mile. (I know, I can’t either.) Some places in North America, like the Appalachian Mountains, have literal tons of the freckled, sticky amphibians. You just do not see them unless you know where to look.
A new study examines how well the tiny but fierce carnivores will fare as climate change warms their mountain homes. The research shows salamanders are surprisingly able to change their physiology in response to the shifting temperature and humidity. Some salamanders are expected to fare better than others, based on their location and size.
“My grandma asked me . . . ‘If all the salamanders in the world died, would I know?’
“And I said, ‘Well, I would,’ ” Eric Riddell said with a laugh. Riddell is the lead author and a postdoctoral fellow at the Museum of Vertebrate Zoology at the University of California at Berkeley.
Riddell said a world without salamanders could be drastically different. Salamanders are abundant in forest ecosystems, and “they eat almost everything that fits in their mouth,” working as a natural control for insects and playing an important role in the energy cycle of forests. Some scientists even make the controversial claim that salamanders could influence the global carbon cycle because they eat so many insects. Some insects shred leaf litter, releasing carbon dioxide into the atmosphere, so in theory, fewer salamanders means more insects and more carbon release.
Many salamander populations around the world have declined because of habitat loss (they need cool, moist forests and undisturbed streams) and a fungal disease that has driven some amphibian species to extinction. Climate change is expected to worsen many of the threats to salamanders, but the new study examined the potential for physiological and behavioral flexibility in seven species.
“Climate change is happening, and it’s human-caused. It’s a real threat to the natural world. . . . Our challenge is to keep ourselves and our world alive,” said Mark Urban, director of the Center for Biological Risk at the University of Connecticut, who was not involved in the study.
The study combined field and published data and lab experiments, along with environmental modeling, to predict the fate of the unexpectedly important salamanders. The goal was to find out how an individual salamander might experience climate warming. The scientists used the data to map out future fine real estate for salamanders, something they hope conservationists will be able to use to help preserve territory for the populations in trouble. The study showed certain areas of the mountains will become uninhabitable, while other areas, at least for now, will remain prime salamander neighborhoods. It might benefit conservationists to focus their efforts on the latter, Riddell said.
Salamanders already have the ability to respond to changes in their environment. They have been around for millions of years and have survived big changes before, just perhaps not quite this big and abrupt.
(To see some really cute middle school kids tell you all about the history of salamanders via science rap, check out these videos.)
This study considers salamander behavior, physical body flexibility and environmental pressure and shows just how flexible salamanders can be in adjusting to their surroundings.
“We can go to the gym and increase our oxygen intake and even build muscles,” Urban said. That’s what the salamanders are doing in response to the small changes in their environment. They are capable of regulating their own water loss, becoming more watertight or leakier depending on how hot or dry the forest is, said Michael Sears of Clemson University, an author of the study. Salamanders do not have lungs, so they get all of their oxygen through their wet skin.
Salamanders have other behavioral tricks for survival. Salamanders can hunker down for a year without food and sometimes spend a couple of years camping underground if the forest is too hot or dry, Riddell said. Salamanders will poke their heads out of the ground and assess conditions before venturing out into the world or deciding to stay home.
For such a stealthy animal, how does one study them?
“For the last five years, I was basically nocturnal,” Riddell said, “I would leave campus around 7 p.m., and I’d get to my field site around 9, 9:30. I would hike to a randomly generated coordinate off trail.” Walking alone in the woods, he would search for the glint of salamander skin in the light from his headlamp.
The Appalachians are full of bears, but that was not the animal Riddell had a bad encounter with.
“I did get a moth stuck in my ear one time,” Riddell said. “It was pretty awful. I tripped, and I fell into a bush. And then I felt it around my ear, and then it ran down my ear canal, and I could hear it flapping its wings and crawling around. . . . I decided to go ahead and just stick it out and continue sampling because I would have had to start my whole experiment over had I stopped. So I sampled the rest of the night with a moth in my ear, which was really awful, and then I went to the ER around 5 a.m. and got it removed.
“But if that ever happens to you, just put water in your ear because their wings get wet, and they can't flap around. That was one of the most valuable things that I ever learned.”
Riddell said there was no long-term damage, just moth wing dust coming out of his ear for the next few months.
Amphibians are extremely sensitive to their environments and at high risk of extinction. This study shows salamanders have an impressive survival tool kit.
“These little critters that we rarely ever see, but we know that they’re super abundant and they’re super important to the forest health, are kind of really resistant to extreme climate fluctuations,” Riddell said.
In the end, it is not quite a story of hope, but more a story of one tough little predator with a soft step and tiny eyes who may be hiding underground for a while longer.