Pacific Northwest Frogs Are a Hop, Skip, and a Jump From Oblivion as Temperatures Rise

Researchers find that extreme drought has triggered a crash in amphibian breeding that bodes ill for a host of other animals.
Cascades frog. (Photo: MyLoupe/UIG via Getty Images)
Sep 11, 2015· 2 MIN READ
John R. Platt covers the environment, wildlife, and technology and for TakePart, Scientific American, Audubon, and other publications.

Climate change is about to make the famously rainy Pacific Northwest a whole lot drier, and that spells trouble for the region’s amphibians and other species.

According to a new paper published in the journal PLOS One, climate change will dramatically lessen the amount of snow and rain that falls on the mountains in California, Oregon, and Washington while increasing the levels of evaporation. The combined effect, researchers found, will leave the amphibians there, already some of the world’s most endangered animals, high and dry.

This past summer—plagued by extreme drought and wildfires—may be a sign of things to come. “The conditions we faced this year would be the new normal by the 2070s or earlier, depending on how quickly greenhouse gas emissions rise,” said the study’s lead author, Se-Yeun Lee of the Climate Impacts Group at the University of Washington.

“I’ve been studying mountain wetlands in the Pacific Northwest for over 15 years, and I’ve never seen so many of them dry as I did this summer,” added another of the paper’s authors, Wendy Palen of Simon Fraser University.

The lack of winter snowpack and high summer temperatures—the hottest summer on record in the Pacific Northwest—resulted in massive breeding failures as well as the deaths of some adult frogs. “We witnessed a near complete reproductive failure of Cascades frogs in Washington’s Olympic National Park this summer,” Palen said. Cascades frogs have been hit by the deadly chytrid fungus, as have other amphibians in the region, and are being considered for protection under the federal Endangered Species Act.

“The Cascades frog is unique among the amphibians of the Pacific Northwest because it does not occur below about 3,500 feet, which means, in population terms, that there is no safety net,” Palen said.

The paper is the first major attempt to understand these wetlands ecosystems, most of which have barely been studied scientifically because of their remote locations. “The thousands of small lakes and ponds that dot the mountains of the Pacific Northwest are extremely poorly described and rarely cataloged,” Palen said. “Part of the challenge is that most can’t be detected by air or satellite photos, and sending people to find and map them is a labor-intensive and expensive undertaking.”

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In the future, drying habitat will affect a wide range of frog, toad, newt, and salamander species, many of which are already on the decline. Hardest hit will be the species that depend on “intermediate wetlands”—which normally ebb as much as two-thirds each year—for breeding. According to the research, at least half of those habitats will become fast-drying ephemeral wetlands by 2070, when they will either disappear or contract by more than 97 percent. These wetlands are the primary breeding habitats for frogs and salamanders.

The amphibians won’t be alone, the researchers said. As they go, other species may also suffer. Birds, snakes, and mammals feed on the amphibians as well as insects and other invertebrates that rely on the ponds and wetlands. Many species—everything from tiny shrews to formidable mountain lions—also depend on the ponds as their main sources of water.

The paper provides a new model for wetlands research. Lee said the methods the researchers devised for the study can be applied to any region where wetlands are of concern. They’re planning possible field studies in the Eastern United States as well as parts of California—all areas where wetlands and the species that depend on them are at risk.