Pamela Flick, California Representative
Good news! Three rare amphibians in the Sierra Nevada are set to hop onto the list of endangered species. The U.S. Fish and Wildlife Service announced in late April that the Sierra Nevada yellow-legged frog (Rana sierrae) and northern distinct population segment of mountain yellow-legged frog (Rana muscosa) have been proposed for endangered species status, while the Yosemite toad (Anaxyrus canorus) may receive threatened species classification. More than two million acres of critical habitat may also be designated to help protect these species in their high elevation territory.
Until recently, the yellow-legged frogs in the Sierra Nevada were believed to be the same species, but they actually took different genetic roads around 2.2 million years ago. These species were historically described as extremely abundant, but today are absent from more than 92 percent of their historic range. The Yosemite toad is currently found in less than half of its former territory.
A majority of the high elevation habitat for these frogs and toads – from 4,500 to 12,000 feet above sea level – is found on public land managed by the U.S. Forest Service and the National Park Service. While these are both federal agencies, their management regimes are quite different. The National Park Service has a robust conservation mission and as such, national park lands have much stronger protections than national forests, where under their multiple use mandate, activities such as timber harvesting, livestock grazing and off-road vehicle use can destroy important habitat. Not surprisingly, populations of these Sierran amphibians have persisted in greater numbers and distribution in the more protected national parks compared to the surrounding lands managed by the Forest Service.
So why are these once common and widespread frogs and toads now dangling so precariously on the edge of extinction? A wide variety of factors have contributed to their decline. As with so many species disappearing around the world, habitat loss and fragmentation are key threats to wildlife. Dams and water diversions, road building, timber harvest and recreational use all lead to loss of habitat as well. Climate change and long-term drought also threaten these highly water-dependent species.
We also lose individual frogs and toads due to predation; non-native bullfrogs eat them, as do fish. This can become a bigger problem when trout are intentionally stocked in historically fishless high elevation lakes and streams, introducing more predators to an area where frogs and toads have had few in the past. Another key threat is disease, including the chytrid fungus, Batrachochuytrium dendrobatidis (Bd), which has been strongly associated with dramatic amphibian declines worldwide.
The Yosemite toad has been hit especially hard by more than a century of unsustainable livestock grazing practices. The high elevation meadows and streamside systems that these toads prefer are extremely sensitive to disturbance. Livestock often congregate in and near sensitive water sources, trampling stream banks and causing wet meadows to lose water critical to the toad’s survival. Approximately one-third of all known Yosemite toad habitat is within active Forest Service grazing areas. Despite the fact that there has been a reduction of livestock allowed in these areas, the damage has been done, and the meadows continue to suffer from eroded channels, bare patches from heavy trampling and grazing, altered plant composition and reduced plant production.
Designation of more than two million acres of critical habitat for these frogs and toads will go a long way toward protecting them. This designation will include lands and waters essential to the conservation of the species and may require special management considerations or protection. But it’s important to note that critical habitat only means that we have to ensure actions taken by federal agencies will not destroy key habitat needed by these species. The designation does not affect land ownership, and continued grazing and habitat development could continue to be an obstacle to these species’ recovery.
Defenders strongly supports the proposed protections for these rapidly declining amphibian species to pull them back from the brink of extinction. We have been leaders in helping to revise national forest plans in the Sierra Nevada to better account for the role of wildlife, and our collaborative work on the Dinkey Landscape Restoration Project on the Sierra National Forest includes some of the lands proposed as critical habitat. We hope that by making their native range a safer place to live, we’ll be helping the Yosemite toad and yellow-legged frogs edge closer to recovery.