Do Herps Hibernate?

Winter water safety: Northwestern Salamanders survive winter in Whistler by remaining gilled (aquatic) as adults. Photo credit: Bob Brett

Spring is such a hopeful time of year to me, when wildlife that hunkered down to survive winter

emerge with the warmer weather and promise of fresh food. Bears are a common example. Like

all mammals, bears control their body temperature internally and are Endotherms (endo =

inside). Their type of dormancy is called torpor and is a “light” form of hibernation.

Often overlooked, amphibians and reptiles also emerge in spring. Collectively known as

herpetofauna, or herps for short, they regulate their body temperature through external sources,

such as the sun, and are Ectotherms (ecto = outside). Their type of dormancy is called

brumation, which allows these animals to survive with extremely little energy. Herps don’t need

to fatten up the same way mammals do; instead, they rely on glycogen, a form of glucose, for

their energy needs. If the weather warms up briefly, animals that brumate can awaken and

forage until the next frost. It’s fascinating to me that brumation varies significantly across

species and locations.

I’ll start with amphibians, those amazing animals which start their lives in water with gills,

followed (typically) by a lung-breathing adult stage on land. Long-toed Salamanders, which

indeed have a long toe on each back foot, are dark with a yellow stripe running down their back.

These salamanders survive winter by heading underground below the frost line. Because they

are not great diggers, they rely on abandoned mammal burrows or natural crevices.

We also have Northwestern Salamanders, which are chocolate brown. In most cases, these

salamanders follow the typical amphibian life cycle. However, in places like Whistler, where

winters are harsher than at lower elevations, these salamanders choose to remain gilled

(aquatic) as adults. This is most likely because underwater temperatures are more stable than

on land.

A young salamander basking in a trailside pond in Whistler. Photo by Bob Brett

What about frogs? Pacific Tree Frogs, the small green or brown frogs we hear singing each

spring, survive winter using an “anti-freeze” mechanism. They flood their vital cells with glucose,

which prevents ice crystals from forming and damaging cell walls. Ice crystals then form

harmlessly in the body cavity and around organs. They are one of the few amphibians that can

freeze solid and survive.

Coastal Tailed Frogs are found in and around cold mountain streams and lack an antifreeze

mechanism. Their tadpoles are unusual, with a sucker-like mouth that clings to rocks in fast-

flowing water. Their cold environment means they develop slowly and can remain as tadpoles

for 2 - 5 years in the stable temperatures of streams that don’t freeze solid. Adults are small,

brown to grey, and survive winter in snow-covered burrows.

The final amphibian I’ll mention is the Western Toad, a type of frog with thicker skin that can

spend more time away from water. Found at Lost Lake, they migrate from the lake to the forest

in August. Like Long-toed Salamanders, they survive winters by being below the frost line.

Unlike salamanders or frogs, toads have back legs designed to dig and can build the tunnels

they need to survive.

Only a brief note about reptiles since Whistler has only four species documented so far due to

our short summer season: Northwestern, Wandering, and Valley Garter Snakes and the

Northern Alligator Lizard. Reptiles are less tolerant of freezing than some amphibians and share

deep, dry dens.

How did you spend your winter?

Written by: Kristina Swerhun

#fauna