Wild Salamanders are Shrinking in North America Due to Climate Change

Climate change may be decreasing species populations, but it's also causing animals to adapt in new and unusual ways. Now, scientists have found that wild salamanders living in North America are shrinking in response to their surroundings becoming warmer and drier.

"One of the stresses that warmer climates will impose on many organisms is warmer body temperatures," said Michael W. Sears, one of the researchers, in a news release. "These warmer body temperatures cause animals to burn more energy while performing their normal activities. All else being equal, this means that there is less energy for growth."

In order to investigate how warmer temperatures might be impacting salamanders, the researchers examined museum specimens of salamanders caught in the Appalachian Mountains from 1957 to 2007. They then also studied wild salamanders measured at the same sites from 2011 to 2012. This allowed them to compare how the salamanders changed through time.

That's not all they did, though. The researchers also used a computer model to create an artificial salamander in order to estimate a typical salamanders' daily activity and the number of calories it burned; this allowed them to see how climate change might affect these species.

The researchers found that the salamanders are indeed getting smaller. With the computer model, they found that they may also have an explanation for this phenomenon.

"Ectothermic organisms, such as salamanders, cannot produce their own body heat," said Sears. "Their metabolism speeds up as temperatures rise, causing a salamander to burn seven to eight percent more energy in order to maintain the same activity as their forebears."

In other words, it seems as if salamanders are becoming smaller simply because they have to devote more calories to a higher metabolism rather than toward growth.

Currently, the researchers plant to compare the salamander species that are getting smaller to the ones that are disappearing from parts of their range. This will give scientists a better understanding as to why salamanders are declining.

The findings are published in the journal Global Change Biology.