Category Archives: Frog hibernation

02/16/16

Caring For Stray Frogs in the Winter

Every winter, frog lovers around the world write to us about stray frogs that wander inside. Last week a man from Maryland wrote about finding a grey tree frog.

Dear Susan,
“I found a gray tree frog hopping around inside our gym here in Maryland. I guess he was drawn inside by the heat. Well, I took him home and have him in a fish tank with water, crickets and artificial leaves for shelter. I’ve got a heating pad that sticks to the back of the tank. I was wondering how cold I could keep my home and still have the frog be ok?” – Gianni

Gray tree frog (Hyla versicolor) by Robert A. Coggeshall on Wikipedia

Gray tree frog (Hyla versicolor) by Robert A. Coggeshall on Wikipedia

For those of you not familiar with grey tree frogs, here’s some information and to read more, a page on Wikipedia:

The gray tree frog (Hyla versicolor) is a species of small arboreal frog native to much of the eastern United States and southeastern Canada.[2]

As the scientific name implies, gray tree frogs are variable in color owing to their ability to camouflage themselves from gray to green, depending on the substrate where they are sitting. The degree of mottling varies.[3] They can change from nearly black to nearly white. They change color at a slower rate than a chameleon. The female does not croak and has a white throat; however, the male does croak and has a black/gray throat. The female is usually larger than the male.

The gray tree frog is capable of surviving freezing of their internal body fluids to temperatures as low as -8 °C.[9]

https://en.wikipedia.org/wiki/Gray_tree_frog

 

When we find stray frogs who haven’t found a place to hibernate, it’s usually because we continue to build within the areas of their habitat, and they may get lost or confused. Going inside where the heat is on shows that this frog is trying to survive through the winter. It’s wonderful when people care enough to help them.

Rescued Grey Tree Frog in Winter

We’ve found a great site with tips on how to care for frogs and get them through the colder months, so they’ll be healthy and ready to go back outside come spring.

How to Take Care of a Pet Frog

 

Here are two of our previous posts that help explain what happens to frogs in the winter:

Winter is Coming: How Do Frogs Avoid Freezing

and

How Frogs and Toads Adapt To Winter’s Chill

 

04/14/14

Bartholomew’s Return Home

The story continues with Jack Stearns, a scientist and meteorologist, who had rescued a bullfrog (Bartholomew) in the middle of Winter.
 

We released Bart back to his pond a little while ago.

Enclosed are pictures of him in his carrier, sitting on the beach, and where he dove into.

I was going to switch to video after the second picture, but before I could he took a three foot leap into the pond and swam very strongly, diving into the debris on the bottom in the last picture. We were both surprised at how strong he was. I figured after a winter of hibernating he would just slowly walk into the water.

The good news from all this is that one can successfully hibernate frogs over the winter time. We had him for 3 months and 3 days and as you can see, he was none the worse for wear.

Our next project is to get a couple of bullfrog tadpoles from our local pond and put them in the tank and watch their transformation into frogs. I did this as a kid. My wife has never seen it so she thinks it would be cool to watch.

— Jack Stearns

Here is the original post when Bart (the bullfrog) was found: Mid-Winter Bullfrog Rescue

Below are a few photographs Jack kindly shared. (Good Luck Bart, we’re excited your journey continues!)

Bartholomew-frog-after-hybernation
 
bullfrog-returns-to-pond-after-winter
 
bullfrog-leaps-into-pond-swims-away

01/14/14

Mid-Winter Bullfrog Rescue

I’m so pleased to share a story that comes by way of Lexington, Massachusetts. Jack Stearns, a scientist and Meteorologist, has rescued a bullfrog in the middle of Winter. Below are the details, correspondence that I shared with The Wandering Herpetologist, Sara Viernum, who offers her advice.

Dear Susan,

I hope you can help me with some information.

Where my wife works in eastern MA there is a large garden wall.  Yesterday one of her workers came in and told her there was a frog on the sidewalk. My wife went out and there was a huge bullfrog on the sidewalk, sitting half in of snow.  By tracing back his path he saw the frog had come out of a huge crack in the wall.  We have had brutal weather the last few weeks with temps as low as -10F with heavy snow.

Because the frog would not survive where it was, (i.e a busy sidewalk and a street treated with chemicals) one of my wife’s coworkers placed the frog in a container, using rubber gloves and brought him home. We are frog and toad people so we are very familiar with their needs and habitats, however a frog appearing on your doorstep in the heart of winter is a new one!

The frog is OK and looks in good shape and very plump. He had no signs of any injury, his eyes are clear and he has a moist skin and is very lethargic, which I would expect being in semi-hibernation.  I placed him in cold water up to his jaw and put him in our coal cellar which is at a constant 34 degrees since I didn’t want to warm him up to wake him up.

Obviously everything is frozen solid so the only choice I have is to keep him where he is.  I looked on him this morning and he definitely is in a hibernation state and you see he is breathing very slowly.

Is there anything else we should be doing until spring arrives?  There is a small pond near our house which is full of bullfrogs and eventually we want to place him there.  The pond has a small current and I know the frogs burrow into the mud there to escape the current which is stronger in the winter.  Right now our frog would be in no state to burrow into the mud.

I hope you can help.  This guy is huge and a lovely specimen and we would hate for anything to happen to him.

Thank you, Jack Stearns, Lexington, MA

bullfrog in lexington MA

Jack,

Susan with Frogs Are Green forwarded me your email about the bullfrog.  Bullfrogs usually hibernate in the mud in a pond in the wild.  Offering your frog wet/moist soil to burrow into might help.

A side note: Bullfrogs are known chytrid fungus carriers.  It’s usually not a good idea to relocate any amphibian to another wetland because of the risk of spreading a disease to another population.  But I know that allowing an animal to perish instead is not a good option either.  I would suggest contacting a local nature center to see if they would be interested in taking the frog.

Thanks for being a friend of amphibians.

Cheers!

Sara E. Viernum

The Wandering Herpetologist
http://www.wanderingherpetologist.com
https://www.facebook.com/thewanderingherpetologist

________________________________________

Sara,

Thank you for response.  I will introduce some moist soil into his container.  He seems to be doing OK so giving him the soil may increase his chances of survival for the next couple of months.

I did not know about the fungus thus I will not put him in the pond near our house in the Spring. The last thing I want is to start an epidemic in another pond. The frogs in that pond are huge and it is fun to hear them croak in the late Spring and early summer and I don’t want to jeopardize those wonderful sounds.

Where our frog was found by my wife on the sidewalk, is not too far from a small pond near the building where my wife works.  It is the only body of water anywhere near the area and had bullfrogs in it.  Would it be OK to release him back to that pond since that is where he likely came from?

Another alternative is if I can’t find a local nature center, I have very small manmade pond in my Hostas garden.  Maybe he would be happy there in the warm weather, maybe he could control my slug and bug problem.

I will keep you posted on our progress.

My wife and I have always been partial to frogs and toads. Where we spent summers on Chatham, MA the house bordered a pond that was full of Spring peepers in the spring and sounds of Green and Bullfrogs in the summer.

Being a scientist myself (Meteorologist), I am well aware of the environment around me and that we all are stewards of this Planet.

Thanks again, Jack
________________________________________

Jack,

Thanks for considering the impacts of introducing the frog into a new population could cause.

I’d think releasing it in the pond nearest the location it was found would be fine.  But he would definitely help control insects in your pond.  The only concern would be him surviving in it next winter.  The pond would need to have enough debris (leaf litter, mud) and deep enough not to freeze solid for it to hibernate in.  
Best of luck.

Sara,

________________________________________

Susan and Sara,

Just a note on how Bartholomew is doing.  The name comes from a pamphlet printed in 1918 called Bartholomew Bullfrog.

In addition to the assistance I received from you two, I also have been getting help from a gentleman in Rockport, MA who oversees the Vernal Pool program in that town.

Right now the Bullfrog is in a large flat container filled with water with soil on one half of the bottom. Once he was transferred to the tank he took a few strokes then settled to the bottom on the end with no soil where he is definitely in a state of hibernation. He looks good and with a little bit of luck we are all set until Spring. Attached is a picture taken this morning.

He has become quite a celebrity where my wife works since most people there now have heard him being found and are curious on how he is doing.

Thanks again for all your help and I will keep you posted on his progress.

Jack

bullfrog rescued in winter MA

Update: 1.20.2014

Susan,

Bartholomew continues to do well.

He started to shed is skin so at the suggestion of Sara I moved him into another tank since she said that bacteria could grow in the dead skin and the water could become a little funky.

Moved him in on Saturday.  This critter is strong!  He is definitely healthy!

Then yesterday he did a sneak out. He managed to lift the corner of the tank top and climb out and went and sat in the corner of the coal room.

I told Sara about the sneak out and she told me that they are notorious escape artists.  She also said that he might be happier in a bed of wet soil.  I got some wet soil with no additives, fertilizers and the like in it.  I put him in that tank and we will see what happens.

With the colder weather moving in, temperatures which now stand at 39F in the coal room will definitely drop to near freezing the next few days and I am sure he will become even less active.

This frog is smart and he knows it!

Sincerely, Jack

10/9/11

Winter is Coming: How Do Frogs Avoid Freezing?

Yesterday while shopping at the mall, I noticed that some stores had already begun putting up holiday decorations. The racks were filled with sweaters and down coats. We humans (at least in the northeast U.S.) are preparing for winter. But what about our amphibian friends? How do they prepare for winter? After all, frogs would seem vulnerable to extreme cold with their thin skins and their need to constantly stay moist.

Actually, we don’t need to worry about the frogs. They are well-equipped to deal with the cold weather, even with Arctic temperatures.

Frogs are ectothermic, which means that they rely on their environment to regulate their body temperature. Birds and mammals, including humans, are endotherms. We generate heat chemically and internally by breaking down food. The bodies of ectotherms reflect the air, ground, and water temperatures around them. One advantage that ectotherms have over mammals is that they can survive for long periods without eating.

In the fall, frogs first need to find a place to make their winter home, a living space called a hibernaculum that will protect them from weather extremes and from predators. The frog then “sleeps” away the winter by slowing down its metabolism. When spring arrives, it wakes up and leaves the hibernaculum, immediately ready for mating and eating.

Aquatic frogs and toads such as the leopard frog and American bullfrog usually hibernate underwater in streambeds or on pond bottoms. Because aquatic frogs need oxygen, they lie just above the mud, or only partially buried in the mud, so they are near the oxygen-rich water. They may even occasionally slowly swim around.

Terrestrial frogs and toads typically hibernate on land. Those frogs and toads that are good diggers like the American toads burrow deep into the soil, safely below the frost line. Other frogs, such as the wood frog and the spring peeper, aren’t good diggers and so must scout out their winter homes in deep cracks and crevices in logs or rocks, or they might dig down into the leaf litter.

These frozen peepers and wood frogs might look dead; their hearts have actually stopped beating. But the partially frozen frogs aren’t dead. Instead, they have a kind of natural anti-freeze in their bodies. Ice crystals form in their organs and body cavity, but a high concentration of glucose in the frogs’ vital organs prevents freezing. When spring approaches and its hibernaculum warms up above freezing, a frog’s frozen body will thaw, and it will come back to life.

As you go about preparing for winter, think of the frogs with their amazing adaptations for survival, safe in their winter homes, waiting for spring.

Here’s a video from YouTube about the hibernation of a wood frog. It’s pretty amazing—take a look!

This is a partial repost of an earlier post from December 2010. Most of the information from the post came from an article in Scientific American, How Do Frogs Survive the Winter? by Rick Emmer.

12/10/10

How Frogs and Toads Adapt To Winter's Chill

It’s mid-December and we’re inside keeping warm, while temperatures outside are below freezing (in parts of the northern hemisphere, that is). But what about our amphibian friends? How do they survive the winter? After all, they would seem vulnerable to temperature extremes with their thin skins and need to constantly stay moist.

Actually, we don’t need to worry about the frogs. They are well-equipped to deal with the cold weather, even with Arctic temperatures.

In the fall, frogs first need to find a place to make their winter home, a living space called a hibernaculum, that will protect them from weather extremes and from predators. The frog then “sleeps” away the winter by slowing down its metabolism. When spring arrives, it wakes up and leaves the hibernaculum, ready for mating and eating.

Aquatic frogs and toads such as the leopard frog and American bullfrog usually hibernate underwater. They don’t, however, dig into the mud like turtles—turtles are able to slow down their metabolism in a much more extreme way than frogs and can get by with almost no oxygen. Aquatic frogs need more oxygen—they lie just above the mud, or only partially buried in the mud, so they are near the oxygen-rich water. They may even occasionally slowly swim around.

Terrestrial frogs and toads typically hibernate on land. Those frogs and toads that are good diggers like the American toads burrow deep into the soil, safely below the frost line. Some frogs, such as the wood frog and the spring peeper, aren’t good diggers and so must scout out their winter homes in deep cracks and crevices in logs or rocks, or they might dig down into the leaf litter.

Yet these frozen frogs aren’t dead—they have a kind of natural anti-freeze in their bodies. Ice crystals form in their organs and body cavity, but a high concentration of glucose in the frog’s vital organs prevents freezing. A partially frozen frog will stop breathing: its heart will stop beating and it will seem dead. When spring approaches and their hibernaculum warms up above freezing, the frog’s frozen body will thaw, and it will come back to life.

As you go about your holiday, all bundled up for the cold, think of the frogs with their amazing adaptations for survival, safe in their winter homes, waiting for spring.

Here’s a video from YouTube about the hibernation of a wood frog. It’s pretty amazing—take a look!

Most of the information from this post came from an article in Scientific American, How Do Frogs Survive the Winter? Why Don’t They Freeze to Death? by Rick Emmer.