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Scientists and students help threatened spadefoot toads

The spadefoot is actually not a toad, but a frog that resembles a toad.

The spadefoot is actually not a toad, but a frog that resembles a toad.

Most Massachusetts residents have probably never heard of the spadefoot toad — so named for its oddly shaped feet. Perhaps that’s not surprising, since it’s considered the Bay State’s rarest frog species, is active mainly at night, and spends much of its life underground.

But students at Concord’s Thoreau Elementary School have gotten to know the unusual little amphibians by raising spadefoot tadpoles as part of an ongoing conservation project with local biologists.

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“The students feed the tadpoles and toadlets, help put the terrarium together, investigate what the spadefoot’s habitat is like, observe, blog, and count the tadpoles and toadlets,” said fifth-grade teacher Susan Erickson, whose students have worked with the creatures each spring since 2010. “They even wrote poems in a blog section called ‘Odes to Spadefoot Toads.’ ”

 This year, however, the odes have had to wait. Because of unusually dry weather, the tadpoles haven’t yet arrived.

Normally, the spadefoots would have begun breeding by early April, said ecologist Bryan Windmiller, a Concord resident who is working on the school project. But thanks to the lack of rainfall this winter and early spring, the ground-water levels on Cape Cod, where the biologists collect the spadefoot eggs, may still be too low to allow the toads’ breeding pools to fill with water, Windmiller said.

He said he will still deliver spadefoot tadpoles to Mrs. Erickson’s class even if they don’t breed until later this spring.

And when that happens, the Concord students will jump into action.

‘In the wild, survival of spadefoot tadpoles to metamorphosis is probably much less than 1 percent.’

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Ellery Winkler, a fifth-grade student who worked on the spadefoot project last year, said she liked watching the tadpoles grow.

But the best part, she said, was the time the food for the spadefoot toadlets — live baby crickets — escaped.

“They weren’t packaged well, and they got away, and it was fun catching them,” she said.

Nathan Hoaglund said he and his classmates last year observed, drew pictures, and blogged about the amphibians.

“It was cool, some tadpoles would have legs and some wouldn’t,’’ he said. “The baby toads hide in the moss, so it’s hard to see them because of their camouflage.”

The reclusive creature “is not the kind of species you’re typically going to stumble across in Massachusetts,” said Ian Ives, director of the Massachusetts Audubon Society’s Long Pasture Wildlife Sanctuary in Barnstable.

The 2-inch-long amphibians have vertical, cat-like pupils, a hardened triangular “spade” on each of their hind feet, and a mating call that has been likened to the sound of a person vomiting. They use their spades for digging, spiraling down backwards, feet first into sandy soil, to depths of up to 8 feet.

Ives said spadefoots can remain underground for weeks at a time, encased in a mucous membrane that helps prevent them from drying out, until a warm spring or summer rain coaxes them to surface for breeding or to search for edible insects.

Even their name, spadefoot “toad,” is a little unusual, as the spadefoot is actually a frog that resembles a toad.

With populations declining because of habitat destruction and such hazards as having to cross busy streets, the spadefoot is listed as “threatened” by the state Division of Fisheries and Wildlife’s Natural Heritage and Endangered Species Program, just one step away from endangered.

Ives and Windmiller are heading up the Eastern spadefoot toad restoration project at the Ashumet Holly Wildlife Sanctuary in East Falmouth, where scientists are building artificial vernal pools in an effort to reestablish the rare toads there. Many of the area’s seasonal pools, which are formed from spring rains and melting snow, were filled in the early 1900s for farming and cranberry bogs.

Ives and Windmiller collect spadefoot eggs from vernal pools during the spring breeding season at Sandy Neck Barrier Beach in Barnstable, where there is still a fairly large population, wait a few days for the eggs to hatch, then distribute the tadpoles to participating schools.

Ten schools across Massachusetts, from elementary to high schools, work with the spadefoot restoration project by raising tadpoles that will later be released at Ashumet Holly as metamorphs, which are tadpoles that have started to grow legs and lose their tails, and baby toads, known as toadlets.

Raising animals in controlled settings like zoos, aquariums, and schools for later release into the wild is called “head starting.” Windmiller said the process gives them a greater chance of survival than they would otherwise experience.

“In the wild, survival of spadefoot tadpoles to metamorphosis is probably much less than 1 percent,” said Windmiller. “Last year, we distributed 2,650 tadpoles to the participating schools, and released 2,250 metamorphs and toadlets into Ashumet Holly.”

Inside the classroom, the tadpoles are fed a mixture of rabbit chow, goldfish flakes, and “some kind of green health food stuff,” said Erickson.

Ives says there’s a huge educational value in working with the schools. It helps both the students and the animals, and produces publishable research for the scientists. Plus, it helps convince the students that animals — and habitats — are worth saving.

For fifth-grade student Amos Decker, who worked with the spadefoots last year, the rationale for the project is pretty straightforward: “It helps the population of the species,” he said. “And it’s fun.”

Don Lyman is a freelance science writer and an adjunct instructor in the biology department at Merrimack College. He can be contacted at Donald.Lyman@merrimack.edu.
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