This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
It only took 23 years but the Oregon spotted frog (Rana pretiosa) has finally gained protection under the U.S. Endangered Species Act. The small, aquatic frogs—which only reach about 100 millimeters in length—have been considered candidates for protected status since 1991. The species has probably already disappeared from its former range in California and in Oregon's Willamette Valley, along with 90 percent of its other range that encompasses its namesake state, Washington State and British Columbia, according to the U.S. Fish and Wildlife Service (FWS).
It's pretty easy to understand why the Oregon spotted frog lost so much territory when you look at the exceptionally long list of threats that the species has faced over the past few decades. On one side you have habitat loss: much of the frogs' wetland territories have been drained, dammed or filled in. On another side the species faces a wide range of invasive species, including American bullfrogs (Lithobates catesbeianus) and largemouth bass (Micropterus salmoides), both of which eat spotted frogs at various times in the latters’ life cycles. The bullfrogs also carry the chytrid fungus, which has further hurt spotted frog populations. And on yet another side we have a variety of introduced plants such as reed canary grass (Phalaris arundinacea), a water-hungry plant that chokes out native flora and creates densely packed areas of vegetation unsuitable for the aquatic frogs, which lay their eggs in shallow waters with low levels of plant canopy. All of this has dramatically reduced the numbers of the remaining spotted frog populations—some have as few as 50 individuals—and left those groups geographically isolated, preventing migration and resulting in very low genetic diversity.
As if all of that weren't enough, scientists say that climate change could dry out the species's habitat even more.
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Both the FWS and the Center for Biological Diversity (CBD)—which has sued to protect the spotted frog and other species—note that protecting this now-rare frog also helps to protect the people who live around it. "Protecting wetlands ... reduces flood danger, preserves water quality and provides habitat for a lot of other wildlife species," CBD endangered species director Noah Greenwald said in a press release.
Although the spotted frog has definitely suffered over the past 23 years, scientists and conservationists have still managed to do some good work to help recover the species and its wetland habitats. The Oregon Zoo, for example, has spent the past 16 years monitoring populations, collecting eggs from the wild, hatching frogs in safe conditions in captivity and releasing healthy adults (that can defend themselves better than tadpoles or juveniles) back into the wild, often in new locations to help establish additional populations. Even inmates at Washington State's Cedar Creek Corrections Center have gotten into the act by helping to breed frogs under the guidance of The Evergreen State College and the Washington Department of Fish & Wildlife.
The Oregon spotted frog will never truly thrive as long as its wetland habitats remain degraded, but the endangered species designation and the ongoing conservation work may help minimize future declines. The frog could also receive further protection: Later this year the FWS will declare so-called "critical habitat" for the species, a process that identifies some of the most important lands and waters to conserve to protect it. (Critical habitat doesn't set aside land for conservation; instead, the process helps to govern federal actions and other activities on federal land that could affect the frogs.) After that, who knows? Hopefully, one day soon it will no longer be as hard to spot an Oregon spotted frog in the wild.
Photo: Teal Waterstrat, U.S. Fish and Wildlife Service