During last month’s warm spell, Emilie Holland saw and heard something she seldom detects this early in the year: the first movement of frogs and salamanders from their woodland wintering grounds to their springtime breeding pools. She observed wood frogs, spring peepers, spotted salamanders, and even a rare marbled salamander near her house not far from the Great Swamp Wildlife Management Area in South Kingstown, R.I.
“We often get pretty early activity here,” said Holland, an environmental scientist for the Rhode Island Department of Transportation and a board member of the Rhode Island Natural History Survey. “For whatever reason, the micro-climate is good for them. The problem is that my hot spot is along a road, and the frogs and salamanders are often crossing it.”
During the same warm days last month, other observers reported hearing spring peepers in North Kingstown and Cumberland, and seeing a red-backed salamander in Middletown.
According to amphibian expert Lou Perrotti, director of conservation at Roger Williams Park Zoo, frogs and salamanders don’t typically migrate to their breeding ponds until mid-March in most areas of the state. During the cold winter of 2015, when many ponds were still frozen until April, amphibian migration was delayed by almost a month. But it’s not unusual for rain showers during an especially warm period in late February to trigger an early migration.
“When that happens, the migration period tends to get extended,” Perrotti said. “A snowstorm or cold snap shuts things down for a while, and then it picks back up again. You don’t have the usual massive explosion of breeding activity all at once. It trickles along instead.”
What happens to the frogs in the ponds when the cold returns and the ponds freeze over again? Not much. Perrotti said the animals are adapted to survive such conditions for short periods of time. In fact, University of Rhode Island herpetologist Peter Paton said he commonly sees wood frogs and spotted salamanders swimming beneath the ice of local ponds in late winter. And wood frogs are uniquely adapted to freeze solid and thaw out later with no negative consequences.
The bigger concern, as Holland expressed, is that many frogs and salamanders must cross roads to reach their breeding ponds, and untold thousands of them get run over by vehicles each year in Rhode Island during those journeys.
“It’s a huge problem, one of the biggest threats to amphibians and reptiles in the area,” Perrotti said. “I’ve seen nights where there were hundreds of smashed wood frogs at just one site. Toads get hammered, too, because they typically have huge breeding explosions over a period of two or three nights. And gray tree frogs, too, which are pretty clumsy on the ground.”
Amphibian movement to and from their breeding ponds will likely continue through April – some species, such as green frogs, migrate later than others — but it typically happens at night when it’s raining. Perrotti and Holland recommend driving carefully at night along back roads in wetland areas during rain showers.
“It’s hard to avoid every frog in the road, especially if you catch it on a good night for migration when they’re everywhere,” Perrotti said.
One strategy that Perrotti said has been employed in western Massachusetts to avoid the problem of amphibian roadkill is the installation of what he calls “salamander tunnels” beneath roadways in areas where large numbers of frogs and salamanders migrate across roads. Barriers along the roadside funnel the animals toward the tunnel, which avoids much of the mortality.
The idea has been discussed in Rhode Island, but the cost is high and finding funding in municipal budgets is an impediment. Signage encouraging drivers to slow down at certain locations is another strategy that officials in the state have considered, though few have been installed to date.
Holland noted that homeowners with sump pumps should regularly check the system for amphibians that wander in and can’t escape.
“I’m constantly fishing salamanders and frogs out of mine,” she said. “People should monitor the sump in their basement and maybe they can keep a local breeding population healthy by not letting the adults die in a pitfall trap that they didn't even know they had.”
Those interested in learning more about local amphibians and participating in a related citizen science project should consider signing up for FrogWatch, a national program administered locally by Roger Williams Park Zoo. Volunteers attend a training program to learn the breeding calls of the various frog species that reside in Rhode Island, then visit a designated pond in the evening once a week from March through August to document breeding activity.