A tiny toad found in a few river canyons in Southern California and Baja may see its legal status change if the U.S. Fish and Wildlife Service has its way. USFWS wants to downlist the arroyo toad (Anaxyrus californicus) from Endangered to Threatened under the U.S. Endangered Species Act.
Though USFWS says that wouldn't change the protection the toad enjoys, moving the species onto the Threatened list would open the possibility that the agency could enact special rules that would erode the species protection.
USFWS says it has no plans to enact any such special rules for the arroyo toad at present. Known as "4(d) rules" after the section of the Endangered Species Act that allows them, such special rules are often written to reduce some protections for other Threatened species, such as gray wolves.
"It's clearly premature to lower the arroyo toad's status from endangered to threatened," said biologist Collette Adkins Giese, who works on amphibians and reptiles with the Center for Biological Diversity. "Protections under the Endangered Species Act have led to conservation actions that have prevented the toad's extinction, but recovery criteria haven't been met and threats remain."
USFWS' recovery plan for the species sets 20 distinct populations of the toad as a threshold: there are just 17 such populations in California.
The arroyo toad is a small, warty amphibian that was once found in much of coastal California. When it was first listed as Endangered in 1994, the toad's range across California had shrunk considerably due to a wide range of factors from development of its habitat, diversion or alteration of native streams, and introduction of predators such as bullfrogs.
One of the biggest factors threatening arroyo toads in California is drought: dry spells can eliminate the shallow, still pools the toads prefer for laying eggs. And USFWS says in its proposal to downlist the toad that the current extreme drought gripping the state is threatening toad populations in most of the river basins in which the species still manages to survive.
Nonetheless, the agency has determined that downlisting the toad is warranted, prompted in part by legal action from the conservative Pacific Legal Foundation. Depending on the results of a 61-day public comment period starting Thursday, that downlisting could become official in August.
The arroyo toad is found in river basins from Monterey County's San Antonio River to a few drainages in Northern Baja California. For the most part a coastal species, the arroyo toad does make it inland as far as the Santa Ana and San Jacinto river drainages, and a few toads have been reported from desert rivers including the Mojave and the Whitewater.
The incredibly informative website californiaherps.com offers this video of a male arroyo toad singing in a creek in San Bernardino County. The toads are well-camouflaged against their riverside habitat, and are often so hard to see that they're trampled by hikers, equestrians, and livestock. Low-water river crossings are especially perilous for the toads, as the shallow water in those crossings strongly resembles the shallow natural pools the toads prefer to lounge in.
Along with bullfrogs, introduced fish and crayfish will readily eat the toads and their tadpoles. That's despite the toads' ability to secrete a potent poison, consisting mainly of bufotoxins, from glands on its skin. Bufotoxin's effects can range from irritation to seizures and death, even in much larger humans, but bullfrogs, garter snakes, and a few other predators have an apparent immunity to the poison. The toads themselves eat invertebrates, with most of their diet composed of ants found on trees.
One of the reasons the toad is in trouble is its very specific habitat demands: the toad requires wooded streamside vegetation (with ants) for most of the year, sandy, exposed banks for burrowing, and slow-water, predator-free pools for egg laying. Those pools must have either sandy or gravelly bottoms without silt, and must also be devoid of vegetation that could entangle the frogs' egg masses.
That's a habitat type that is about as vulnerable to human disturbance as you're likely to find in California, vulnerable to suburban development; pollution; siltation from grazing, fires, or off-road vehicles; invasion by competing or predatory species; and drought.
Though USFWS says it has no 4(d) rules planned for the toads, such rules are often used to provide management flexibility when Threatened species come into conflict with humans. The gray wolf 4(d) rule referred to earlier allowed state game officials to shoot wolves in Minnesota if they were known to have attacked livestock; another 4(d) rule enacted after the polar bear was listed as Threatened in 2008 allowed non-lethal control of the bears that would otherwise have been considered a harassment "take" of the species.
Closer to home, USFWS developed 4(d) rules for the Threatened California gnatcatcher in 1993 that allowed development of gnatcatcher habitat -- legally considered a "take" under the Endangered Species Act -- as long as the development took place as part of a Natural Communities Conservation Plan managed by the Department of Fish and Wildlife. Under the 4(d) rules for the gnatcatcher, dozens of developments have been allowed in gnatcatcher habitat since the controversial listing.
Whether USFWS will propose 4(d) rules for the arroyo toad at some later date remains to be seen. We'll be watching.