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Amphibians in U.S. Declining at “Alarming and Rapid Rate”

The views expressed are those of the author and are not necessarily those of Scientific American.

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Yellow-legged frogA new study finds that frogs, toads, salamanders and other amphibians in the U.S. are dying off so quickly that they could disappear from half of their habitats in the next 20 years. For some of the more endangered species, they could lose half of their habitats in as little as six years. The nine-year study, published on May 22 in PLoS One by scientists from the U.S. Geological Survey (USGS), examined population trends for 48 species at 34 sites across the country.

The researchers found that on average amphibian populations were shrinking a surprising 3.7 percent per year. “Even though these declines seem small on the surface, they are not,” lead author Michael Adams, a USGS ecologist, said in a prepared release. “Small numbers build up to dramatic declines with time. We knew there was a big problem with amphibians, but these numbers are both surprising and of significant concern.”

Worse yet, the scientists found that species currently classified as “endangered,” “vulnerable” or “near threatened” on the IUCN Red List of Threatened Species were declining much faster, at an average of 11.6 percent. Species listed as “least concern” on the Red List were declining at a slightly slower-than-average rate of just 2.7 percent.

The researchers did not look at specific causes of death—although past experience tells us amphibians suffer from habitat loss, climate change, pollution, invasive species and the deadly chytrid fungus. But they did discover that populations dwindled throughout the country, even in national parks and wildlife refuges that are supposedly protected for conservation purposes. “The declines of amphibians in these protected areas are particularly worrisome because they suggest that some stressors—such as diseases, contaminants and drought—transcend landscapes,” Adams said. “The fact that amphibian declines are occurring in our most protected areas adds weight to the hypothesis that this is a global phenomenon with implications for managers of all kinds of landscapes, even protected ones.”

A FAQ published in conjunction with the study explains why the drop in amphibian species matters: “[Amphibians] control pests, inspire new medicines, feed other animals and help make ecosystems work. They are inherently valued by people of all ages—watching tadpoles and listening to frog calls are some of the most accessible interactions we have with the natural world.”

The study was conducted under the auspices of the USGS Amphibian Research and Monitoring Initiative, which was established by congressional mandate in 2000 to monitor, research and conserve the country’s amphibian populations.

Previously in Extinction Countdown:

Photo: A Sierra Nevada yellow-legged frog (Rana sierrae) in Yosemite National Park. By Devin Edmonds , USGS

John R. Platt About the Author: Twice a week, John Platt shines a light on endangered species from all over the globe, exploring not just why they are dying out but also what's being done to rescue them from oblivion. Follow on Twitter @johnrplatt.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. Spin-oza 9:01 am 05/24/2013

    Ahem… it’s the proverbial canary in the coal mine… and the news is decidedly not good for our planet… our habitat for humanity.

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  2. 2. greenhome123 1:53 pm 05/27/2013

    Thank you Monsanto, Sygenta, and Dow for doing your part in killing off these pesky amphibians.

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  3. 3. jmb0124 9:28 pm 02/2/2014

    I just learned about the problem of amphibian decline in my ecology class and we talked about all of the points that were mentioned above. I learned Professor Tim Halliday that almost 200 species have gone extinct within the past few decades and this rate hasn’t been seen since the extinction of the dinosaurs. However, the worldwide biodiversity crisis has also affected other species, just not as drastically. I also learned that there is not a single cause for the decline but rather many factors such as habitat destruction, climate change, and over-exploitation. I agree with the first comment that this news is not good for our planet because if this is happening to all the amphibians what does this mean will happen to humanity. Future thoughts to be thinking about are what we can do to stop this problem. A few solutions that I have read about are captive breeding, reintroductions, and non-native species removal.

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