Climate Change Could be Making Salamanders Smaller

Experts suggest that salamanders in North America are shrinking in size because of climate change - where warmer and drier seasons are forcing them to burn more energy on a regular basis.

According to a study published in Global Change Biology, salamanders within the past few decades are on average eight percent smaller than older generations.

"One of the stresses that warmer climates will impose on many organisms is warmer body temperatures," author Michael W. Sears said in a statement. "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."

According to the study, Sears and his colleagues used simulated minute-by-minute daily behavior of modern salamanders, and calculated energy burnt in these actions using weather records or sample salamander's natural habitats. They found that modern salamanders are just as active as their ancestors, but by doing so, are leaving less energy for growth.

Sears explained that salamanders cannot produce their own body heat, instead using the temperature around them.

"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," he said.

Co-author Karen R. Lips adds that the rate at which salamanders have been shrinking in size is one of the largest and fastest rates of change ever recorded in any animal data. The study reveals a "clear correlation" with climate change, but she explains that it can also have genetic influences likewise driven by the conditions of changing habitat climate.

She goes on to say that if genetics are not a factor, and the salamanders are just simply physiologically adapting, "it gives us hope that some species are going to be able to keep up with climate change."

The team says their next step is to study the similarities and differences between salamander species that are just shrinking - like those seen in North America - verses ones that are disappearing entirely from habitats that were once crawling with the tiny creatures.