Toads on high: tracking and photographing boreal toads

  • Once abundant in the Southern Rocky Mountains, the boreal toad is a rare sight today.

    David Herasimtschuk
  • U.S. Forest Service biologist Kelly Larkin hikes into the Colorado high country, in search of boreal toads.

    David Herasimtschuk
  • Doreen Sumerlin observes tadpoles in a high mountain pond.

    David Herasimtschuk
  • Brock McCormick and Doreen Sumerlin swab a boreal toad for evidence of chytridiomycosis.

    David Herasimtschuk
  • With a grip around the female’s chest, a male boreal toad fertilizes the thousands of eggs she produces.

    David Herasimtschuk
  • A toad jumps through tall wetlands vegetation; female toads have been observed to travel more than a mile from their breeding ponds

    David Herasimtschuk
 

On a warm July morning, two biologists and three volunteers scramble up an alpine valley on the Williams Fork of the Colorado River, high in the Colorado Rockies. Their boots, scrubbed with disinfectant at 6 a.m., have become mud-sicles squelching through sucking, oily-sheened bogs. Hordes of mosquitoes pursue with zen-like focus. It's not exactly Club Med, but it is toad country. And the biologists couldn't be happier.

They skirt silted-up beaver ponds and streams through thickets of willow, waving pruned twigs above the grass like blind men, trying to flush boreal toads. The amphibians -- whose Southern Rockies population ranges from southern Wyoming to northern New Mexico -- are famous for hopping between marshes, lakes, wet meadows, streams and ponds at chilly, lung-straining altitudes that reach 11,500 feet. They are the only Western reptile or amphibian that does so.

"Oh, toad!" calls U.S. Forest Service wildlife biologist Brock McCormick. It squeaks like a grass flute as he plucks it from a pond. He rubs its belly and webbed feet with a cotton swab, which he seals in a test tube.

Inky tadpoles a centimeter or so long wriggle below. Aging beaver ponds like this provide perfect tadpole habitat, since their shallows warm quickly during alpine summers, and there's no shortage of toads-to-be this year. But even in a typical year, only about 10 percent survive. This year, there may be fewer: Late snowmelt has set them back several weeks, making it harder for them to complete metamorphosis before snow flies. But there's a graver threat, one that may lurk in that test tube.

Chytridiomycosis -- a skin disease, perhaps first spread by escaped African clawed frogs used for pets or pregnancy tests in the mid-20th century, and later by non-native bullfrogs and native chorus frogs -- has ravaged boreal toad populations in Colorado and killed amphibians around the world. It's caused by the swimming spores of an aquatic fungus called a chytrid.

Boreal toads were listed as endangered by Colorado in 1993, and also receive special protections in New Mexico and Wyoming. Several state and federal agencies monitor breeding sites for tadpoles and toadlet survival, watching for chytridiomycosis. But no one can say exactly how much the toads have declined, since no one really looked until the fungus was established. The U.S. Fish and Wildlife Service is currently reviewing a petition to list the toad as federally endangered, and anticipates publishing its findings in 2012.

There is cause for hope: A few Colorado boreal toad populations have managed to persist even after fungus arrival, and testing reveals they may have some genetic resistance. A handful of reintroduction efforts are also under way in New Mexico and Colorado. But reintroduction is hard because the fungus may persist even when amphibians are gone, and it isn't easy to detect in their absence.

These particular ponds on the Williams Fork are among the few places in Colorado free of chytridiomycosis, and their remoteness -- they are many rugged hours from civilization -- keeps them relatively free of human traffic that might carry spores. But humans are not the only visitors; well-trod game trails lace the bogs.

"It's not like we're cleaning elk feet," McCormick says.

The team has just turned homeward in a sudden downpour when Forest Service wildlife biologist and Region 2 herptile coordinator Doreen Sumerlin shouts, "Oh, my God, toad, toad, toad!" as one hops right beside her.

Minutes later, the third toad of the day is captured.

"Huge female," Sumerlin says.

"Toadapalooza," McCormick adds thoughtfully.

In this high valley, that is, so far, the case.