By TODD McLEISH/ecoRI
News contributor
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| There is just one population of eastern spadefoot toads left in Rhode Island. (Brad Timm) |
The state’s rarest toad is round and
short-legged with bulging eyes and a spade-shaped protrusion on its hind feet
that enable them to corkscrew themselves into the ground, where they stay moist
and cool and avoid predators.
But there is just one population of
eastern spadefoot toads left in Rhode Island, here in Richmond, and they
haven’t reproduced since 2014.
Scott Buchanan, a herpetologist with the Rhode Island Department of Environmental Management (DEM), called the toads “the best example of a species that, as far as we know, is on the verge of disappearing from Rhode Island.”
Scott Buchanan, a herpetologist with the Rhode Island Department of Environmental Management (DEM), called the toads “the best example of a species that, as far as we know, is on the verge of disappearing from Rhode Island.”
University of Rhode Island
herpetologist Nancy Karraker and research associate Bill Buffum are trying to
forestall that possibility by building additional wetland habitat for them in
several communities around the state.
The first of these manmade breeding
pools were built May 13-15 on property owned by the Richmond Rural Preservation Land
Trust.
“Spadefoot toads breed in the most
ephemeral of vernal pools,” Karraker said. “They use what most would call a
puddle in the middle of an agricultural field, with no forest canopy cover, and
they’re filled by torrential storms that occur in May and June. Those big
storms that produce thunder and lightning and an inch or more of rain in 24
hours brings the toads up to breed.”
When these conditions occur, the
toads lay their eggs within a day, the eggs hatch into tadpoles a day or two
later, and they complete their metamorphosis into toadlets and hop away into
the forest three weeks after that, she said.
Unfortunately, the proper conditions
haven’t occurred at the right time to inspire the toads to emerge and breed in
the past five years.
Karraker studied spadefoot toads for three years in Virginia, where they are quite common, and documented their nighttime emergence to feed, their travels across the landscape from forests to breeding ponds, and their corkscrew behavior back into the sandy soil.
“But we have no idea what they do
here in Rhode Island,” she said.
An endangered species in the state,
spadefoot toads are at the northern limits of their range in southern New
England, which Karraker said means the conditions are probably not ideal.
“But they’ve been here for
millennia, evolving and changing with their environment,” she said. “They just
haven’t been able to deal with the fact that we’re destroying their breeding
habitat.”
Karraker and Buffum are working to
change that with a project they are calling “Operation Spadefoot RI.”
They spent three years gathering funding and a coalition of partners to build just the right kind of ephemeral pools the toads require for breeding. They brought together more than two dozen volunteers to build the first two pools not far from the state’s historic spadefoot toad population in Richmond.
They spent three years gathering funding and a coalition of partners to build just the right kind of ephemeral pools the toads require for breeding. They brought together more than two dozen volunteers to build the first two pools not far from the state’s historic spadefoot toad population in Richmond.
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| Spadefoot toads have stout bodies that reach about 2.5 inches in length. Their hind feet are large and contain hard tissue that allows them to function as ‘spades’ for digging in loose soils. (Nancy Karraker) |
The partners include URI, DEM, the
Natural Resources Conservation Service, the Rhode Island Natural History
Survey, The Nature Conservancy, Roger Williams Park Zoo, the Rhode Island
Conservation Stewardship Collaborative, the Beech Tree Foundation, and the
Richmond Rural Preservation Land Trust.
Kentucky-based wetlands consultant
Tom Biebighauser, who built 21 spadefoot toad breeding pools in Massachusetts
in recent years, as well as pools for other amphibians in the United States and
Canada, led the project.
Eighteen pools were designed last year for sites in Richmond, South Kingstown, and Barrington, and if they are successful at hosting breeding populations of the toads, additional pools may be built elsewhere.
Eighteen pools were designed last year for sites in Richmond, South Kingstown, and Barrington, and if they are successful at hosting breeding populations of the toads, additional pools may be built elsewhere.
The process involves using an
excavator to dig a hole 12-15 inches deep and 40-60 feet in diameter, covering
it with what Karraker called “geotextile pads” to provide a cushion beneath a
specially made liner, covering the liner with additional geotextile pads, and
then spreading soil on it and scattering straw around it for erosion control.
“The reason they need such a
specific kind of pool is so they aren’t competing with other tadpoles or
dragonfly or beetle larvae. They’re in there by themselves,” Karraker said.
“It’s an ingenious ecological strategy.”
Karraker hopes that the toads from
the Richmond population will find the newly constructed pools on their own. If
they don’t, she intends to bring tadpoles from the historic site to the new
pools. Tadpoles will have to be relocated to the pools that will be built next
year on land owned by the South Kingstown Land Trust and the Barrington Land
Conservation Trust.
“Our grand plan over the long term
is to perhaps head start the tadpoles at the zoo — and possibly at the Greene
School (in West Greenwich) to get kids interested in the project and raise
public awareness of this charismatic creature — before releasing them in the
new pools,” Karraker said.
“We’ve been going around the state for years looking for other breeding populations, so the chances are we would have detected them if there were any. But maybe with an increase in outreach and public awareness, we’ll learn about other existing populations, which would be a great thing.”