Conserving Imperiled Amphibians and Reptiles in a Changing Climate
As the climate changes, our resolve to protect vitally important wildlife remains steadfast. Climate change affects everything in the natural world, and modern conservation efforts must account for its impacts. For amphibians and reptiles, in particular, even small environmental changes can have big effects. Their internal body temperatures fluctuate with the temperature of their surroundings (called ectothermic), and therefore, their behavior and health are also affected. Most amphibians have permeable skin, making them hypersensitive to moisture changes. Many reptiles, like alligator snapping turtles, have temperature-dependent sex determination, so shifts can throw off male-female population balances. And already, these critical species are in steep decline—recent news indicates that one in five reptiles are imperiled, along with a third of amphibian species.
Let’s be clear: climatic shifts have occurred for as long as the earth has been around. But what we are seeing today is quite different than what were typically more gradual shifts in the past. The world has warmed by roughly two degrees Fahrenheit over the last century alone.
The ways climate change interacts with other challenges that imperiled wildlife face are varied and sometimes unexpected. Here are just a few examples:
Increased fire intensity and frequency in habitats that are not adapted to frequent fire have the obvious effect of destroying habitat, but they also cause increased sedimentation in waterways. We’ve seen these effects in New Mexico recently. For a species like the Chiricahua leopard frog, that sedimentation chokes streams and destabilizes the food chain they depend on.
Climate change also increases the prevalence of diseases like chytrid (pronounced kit-rid), a fungus that hinders amphibians’ ability to breathe through their skin. In fact, the recent “thermal mismatch hypothesis” predicts that amphibians suited to cooler climes are extra vulnerable to warmer-adapted diseases because they are stressed by the temperature and then exposed to the new or more prevalent disease.
The effects of climate change stack up for a species like the Cascades frog of the Pacific Northwest. Higher winter temperatures cause their metabolism to increase at a time when there’s not as much food available. On top of that, there’s less snow, and wetlands dry up sooner, desiccating tadpoles—a waterfall of effects that showcase how complex the repercussions of climate change can be.
But there’s still hope. The last Ice Age, though it carried a high cost to life, proves that the world’s flora and fauna can overcome temperature challenges. We just have to give them the tools and opportunity to do so.
There are many frameworks biologists use to approach conservation. A particularly helpful one is used by the U.S. Fish and Wildlife Service to recover endangered species, and it’s well aligned with what we need to do for amphibians and reptiles in the face of climate change. That framework is called the 3 Rs: Resiliency, Redundancy, and Representation.
Resiliency refers to the size of a population. Put simply, the more individuals there are in a population, the better their chance for survival. For example, suppose the effects of climate change result in a 20% reduction in a species’ population size. In that case, losing 20% of 100 individuals is less damaging than losing 20% of 10 individuals. This is why it is so important to boost the size of small populations through efforts like reducing mortality of young individuals by raising them past their most vulnerable stage (called headstarting) in controlled facilities.
Redundancy refers to the number of populations. We need to create the habitat for a species to establish more populations, or, in some cases, we need to translocate or reintroduce animals back into suitable habitats. Much like resiliency, this is a numbers game. The greater number of populations, the lower the risk the species will be wiped off the map by a catastrophic event such as a hurricane or disease outbreak.
Representation is the most abstract, but in the context of climate change (or any change) is incredibly important. It’s basically genetic diversity, which represents the ability of a species to adjust responses to variations in conditions, or adaptive capacity. The more copies of a certain set of genes a species contains, the higher chance that one of those genes will give the individuals the edge they need to survive the various climate change stressors.
In the face of climate change, ARC’s work is focused on using the 3Rs framework to protect amphibians and reptiles. We work to increase population sizes, create and restore suitable habitats to ensure greater numbers of populations, and safeguard genetic diversity in those populations. Reptiles and amphibians have walked, swum, and crawled our landscapes for millions of years, and with your help, we aim to keep it that way.