GEOFF CUNNINGHAM Jr. gcunninghamfosters.com
Published Thursday April 23, 2009 at 3:15 am
Updated Thursday April 23, 2009 at 5:35 am
PORTSMOUTH — It's springtime and when it rains the frogs pour out onto area roadways with purpose.
Ever wonder what prompts the miniature road hazards to risk their lives and hit the pavement during stormy April nights?
Experts say the answered is simple ... sex and food.
"This is the time of the year when it's all happening. They are emerging from places they spent the winter and they are migrating to habitats where they will be breeding," said Matt Tarr, a wildlife specialist for UNH Cooperative Extension.
Tarr said the busiest time for frogs is upon us with the annual springtime migration and breeding season in full effect.
There are 10 species of frogs native to New Hampshire ranging from the American toad to the bullfrog.
Tarr said the bullfrog can grow as large as a person's hand while the "spring peepers" — the species now singing in chorus in area wetlands — are only half the size of a person's thumb.
During rainy nights drivers may have noticed dozens or even hundreds of frogs crossing roads in the area despite the danger of being hit.
Tarr said frogs travel out onto the pavement at this time because moist nights make for good amphibian travel weather.
"They breathe through their skin so they are susceptible to drying out when the sun is out. When it's rainy they can go wherever they want and not worry about it. They tend to be the most active at night," Tarr said.
Mike Marchand, a wildlife biologist with New Hampshire Fish and Game, said frogs can be seen on the roads throughout the year during storms.
"When they move, it's typically in the rain," said Marchand, adding the first big spring rainfall tends to bring them out of hibernation.
Tarr said green frogs and bullfrogs winter underwater by hunkering down in mud while other species like wood frogs actually go into a hibernation state above ground by employing a type of "antifreeze" in their body that prevents the cold from killing them.
Experts say many frogs travel across pavement from their winter hibernating spots to get to wetlands where they can breed.
Tarr said the road also provides warmth as it holds the heat from the day better than the ground. Frogs also find things like worms and insects on the pavement to feast on, he added.
Tarr said species like the peepers breed early because they must lay their eggs before temporary springtime pools dry up while other species breed later into the season because they do so in permanent wetlands.
UNH Cooperative Extension officials are concerned about roads that run through wetlands because frogs and other amphibians are often run over more often during their travels.
On Tuesday dozens upon dozens of frogs could be seen out on the roads in the Seacoast region and many didn't make it across the road.
Tarr said frogs and toads are remarkably adapted to their environment with features like camouflage and toxic chemicals that can be excreted to make them the last thing on the menu for many animals.
However, he said they certainly aren't aware of the danger of vehicles.
"Most of the time the first time they are being educated about a car they are being squashed," Tarr said.
Marchand said the road is certainly a "risky" place for frogs to be considering that many motorists don't even see them.
"There is certainly a high mortality rate on nights when it's raining. When I drive I'm cringing and slowing down," Marchand said.