On a recent evening, when heavy rain, high winds, and thunderstorms were lashing the Boston area, biologist Tim Beaulieu left the comfort of his Somerville home and headed north to Plum Island. Beaulieu had a hunch that the rain and relatively warm temperatures might be enough to coax an unusual animal out of hiding.
When Beaulieu arrived at Parker River National Wildlife Refuge , he drove slowly down the dark road through the pouring rain.
“The first parking lot was underwater,” he said.
But a little further down the road, Beaulieu spotted what he was looking for: an eastern spadefoot, Massachusetts’ rarest toad species.
Beaulieu said he was excited to see his first eastern spadefoot in the wild. After three hours of cruising through the refuge, he found 21 more of the unusual little amphibians, happily hopping around in the rain.
Beaulieu had signed on with biologist Bryan Windmiller, executive director of Concord-based Grassroots Wildlife Conservation, last summer to help conduct a spadefoot survey of the refuge, which stretches from Newburyport into Newbury, Rowley, and Ipswich. But they were unable to find any of the elusive toads, said Beaulieu, probably because of the severe drought that likely kept the spadefoots in their burrows, deep beneath the sand.
“Eastern spadefoot toads spend most of their lives underground and can survive long periods of drought in very dry, sandy environments, a very difficult habitat for frogs and toads, which need to maintain moist skin at all times,” Windmiller said in an e-mail. “They are fantastic burrowers and can corkscrew themselves into even firmly packed sand in seconds.”
The Massachusetts Division of Fisheries & Wildlife website said spadefoots are neither a true frog nor a true toad, but belong to a primitive amphibian family. They’re named for hard, sharp-edged, sickle-shaped spades on their hind feet, which biologists think helps them dig into soil. They burrow backward and twirl their bodies around in a corkscrew motion. Spadefoots can burrow up to 8 feet deep. They also have unusual cat-like, vertically elliptical pupils.
“Eastern spadefoot toads are, in many ways, the most unique amphibian species in Massachusetts,” said Windmiller. “They derive from an ancient desert-adapted lineage and likely spread into New England during past periods when the climate was drier than today.”
Windmiller said ants, beetles, and spiders seem to be some of the eastern spadefoots’ favorite food. He said spadefoots have somewhat toxic skin secretions, but they are still preyed upon by snakes, and likely by nocturnal mammals and occasionally owls.
According to the Division of Fisheries & Wildlife, the eastern spadefoot ranges from Louisiana to southern New England. In Massachusetts, it is listed as a threatened species, and lives only in a few scattered locations, including the Cape and the Islands, parts of the Connecticut River Valley, and in coastal areas of northeastern Massachusetts.
Windmiller said Plum Island is the northernmost coastal population of eastern spadefoots in the United States. He said the purpose of the survey there was to gather data on relative population size, habitat preference, and distribution of spadefoots at the refuge.
Nancy Pau, wildlife biologist at the Parker River refuge, said in an e-mail that it’s hard to estimate the eastern spadefoot population size because it fluctuates a lot. But based on surveys in the early 2000s, the population appears to be fairly abundant.
“They are explosive breeders,” said Pau. “Some years, they are everywhere, and other years they are pretty rare and may not breed at all.”
The Division of Fisheries & Wildlife describes spadefoot mating as “an orgy of raucous squawks and frantic courtship,” with the males’ mating calls sounding like “explosive, low-pitched grunts.”
“I love hearing their call,” said Pau. “Every creature is unique . . . and people, as the stewards of the Earth, should make sure that we protect areas for these special animals, so that our children can enjoy them, too.”