Our Disappearing Amphibians
By Shelley Harms

American Bullfrog by Leslie Watkins, ©2015

After a long, snowy winter, the calls of wood frogs and spring peepers from Norfolk’s thawing  ponds are a welcome sign of spring. Especially this year, when the wood frogs made their latest appearance in memory in my pond, still half iced-over when a few hardy little souls started calling on April 14. Since then, the few calls have swelled to full-blown “quacking,” and the peepers joined in on April 17.  At last, all is right with the world.

But will the vernal chorus be there for us in years to come? In what is being called the sixth mass extinction on earth, amphibians are leading the way, disappearing world-wide at an alarming rate. With their permeable skins, amphibians are very sensitive to pollution, changes in pH levels, climate change, and disease. At least one-third of all frog, toad, and salamander species are threatened with extinction, and even species not currently endangered are suffering drastic declines in population.

Sudden mass die-offs have decimated tropical species like Panama’s golden frog and Costa Rica’s golden toad, and have also occurred closer to home, in the death of hundreds of spring peepers in Maine and up to a thousand wood frogs and spotted salamanders in Massachusetts in 2000. A more gradual but marked decline in vernal pool species such as wood frog and many salamanders is occurring in Connecticut, as development destroys or isolates the vernal pools and upland habitat where they live.

So far, Norfolk has been spared a noticeable loss of our frogs, toads, newts and salamanders.  According to scientist Michael Klemens, author of “Amphibians and Reptiles in Connecticut,” Connecticut’s northwest corner is “a stronghold for vernal pool species,” because we still have large intact landscapes where the amphibians can move to and between suitable wetlands for breeding. (Dr. Klemens is perhaps best known in Norfolk for finding the rare Jefferson salamander in a large vernal pool at the proposed Yale Farm golf course site.) He tells a cautionary tale of a town to the south, where every effort was made to preserve several vernal pools, but the connecting upland habitat was developed. Those pools have died a slow death, as their frogs and salamanders lost the upland habitat associated with their breeding pools. As Dr. Klemens warns, “saving the pool but not the landscape doesn’t prevent decline” of the vernal pool amphibians.

Some amphibians are actually benefitting from the loss of vernal pool landscapes. Bullfrogs and green frogs are “increasing tremendously,” Dr. Klemens says, replacing vernal pool species like wood frogs, as they are “generalists” that can live in human-altered habitats.

But even the generalists are vulnerable to other threats. Dr. Klemens warns against moving amphibians around, citing “huge, emerging problems with disease.” Diseases and fungus introduced by taking amphibians as pets or for research then releasing them into the wild, have been associated with mass amphibian die-offs.

Most important for amphibians here in Norfolk, Dr. Klemens says, is to maintain our large, intact landscapes that provide vernal pool species with the complex habitats they require. By preserving this still-intact habitat, Norfolk may still have the opportunity to prevent the loss of our beloved harbingers of spring.