The Hippo


Jul 24, 2019








Fire salamander crawling on the snow. Courtesy photo.

Frozen frogger
Unseasonable weather no threat to migrating amphibians


 By Ryan Lessard 
Biologists believe small amphibians will make their yearly trek to their breeding grounds en masse this week, in a tradition known colloquially as the “Big Night.” While that’s a little later than usual, the extended cold weather that’s characterized this spring in New Hampshire is not likely to have any long-term negative effects on frogs and salamanders.
Big Night
Usually the Big Night happens between mid-March and mid-April. While biologists have recorded some “pulses” of amphibian migration activity, the bulk of it isn’t expected until there’s an evening in mid-40-degree temperatures with some rain. 
“This time of year the frost starts to melt, the weather starts to warm up a bit and salamanders will come out of the ground and will come out of muddy substrate or underwater, and they’ll be moving to breeding pools,” said Fish and Game biologist Joshua Megyesy. “And frogs like spring peepers and wood frogs will do the same thing.”
This activity is most noticeable on roadways. Often, motorists will report seeing several frogs and salamanders crossing the street, some not lucky enough to make it to the other side.
Thaw-freeze cycle
This spring has seen a tiresome series of false starts. But Megyesy said the thaw-freeze cycle is pretty common in the spring. And even though Concord saw all-time record low temperatures on April 15, they were still within a tolerable range for hearty amphibians.
If anything, it’s slowed them down a little, but Megyesy said they will not be deterred from their mission to reach vernal pools for breeding.
“They’re pretty well adapted to it. Wood frogs can almost freeze solid,” Megyesy said.
Wood frogs have a natural glucose in their blood that acts as a sort of antifreeze and prevents cell degradation.
Other species, like spotted salamander, blue spotted salamander and the state endangered marbled salamander, will burrow into soil or leaf litter and go underwater. This time of year, water bodies are not freezing solid, so even if it gets cold enough to freeze the surface, the deeper water is a thermal refuge, Megyesy said.
In some extreme cases, individual frogs and salamanders may run the risk of fatally freezing or drying out, or for eggs in vernal ponds to freeze and die if they’re close to the surface. But it hasn’t happened in any large numbers.
“We don’t ever see any mass die-offs or anything like that from the freeze-thaw cycle,” he said.
While a slightly postponed breeding season is nothing to be concerned about, a fast rate of land development has proven to be one of the drivers hurting amphibian populations. The cold-blooded critters are increasingly cut off from their hibernation spots and their breeding grounds by roads and buildings.
Climate change is also playing a more gradual role in threatening amphibian species. 
Another thing that Megyesy said would have long-term consequences is if spring became unseasonably warm and the Big Night happened far too early.
“The only thing that’s a concern is the timing of some of these things,” he said.
That could mean migratory predator species that rely on eating amphibians and their eggs during the breeding season could miss the lunch bell by arriving after those eggs have already hatched.
That could affect species like mink, wood ducks and some rare and endangered turtle species such as Blanding’s turtle or spotted turtle, which rely heavily on salamander and frog eggs.
The public can help biologists track amphibian activity by reporting sightings, peeper calls or known vernal pools at
“[Conserving amphibians] is sort of a multi-pronged approach but we’ll just have to keep working at it, keep learning, and public input is a big part of that,” Megyesy said. 

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