🐸 This Site is For Sale: Learn More

Wood Frogs

Wood Frogs are small brown and black Tree Frogs that live around 3 years and can be found in North America as far as Alaska. Wood Frogs been described as biological miracles because of how they freeze to hibernate and survive Winter.

Wood Frog Call

Common NameWood Frog
Other NameN/A
Scientific NameLithobates sylvaticus
LocationsAlaska, Northeast North America
CharacteristicsBlack marking across eyes, like a mask
ColorRed, green, brown, or gray
Females brighter colored than males
OriginNorth America
Conservation StatusLeast Concern
SpeciesL. sylvaticus
Max Length3.25 in
Max Weight.28 oz
Lifespan3 years

Wood Frogs Can Survive Extreme Conditions 

Wood Frogs can be found in Alaska and Northeast North America. To survive the long and very cold winters, they have adapted hibernation methods that are only seen in Tree Frogs that live in climates where they need to hibernate during winter.

In the Winder, the Wood Frog’s body freezes and its heart stops beating. They also stop breathing and remain in this state until Spring.

When organic material freezes, whether it is animal or plant, ice crystals form in the cells that break the cell structure. When the frozen material thaws, the cells are irrevocably damaged. Tree frogs, however, have developed a method to avoid cell damage while freezing.

Tree frogs develop a type of antifreeze based on glucose in their cells that prevents ice crystals from forming.

When the sun comes out and temperatures rise, Wood Frog and other Tree Frog species that live in North America like Spring Peeper that out and are for mating, as if nothing unusual had happened to them.

Wood Frogs Can Help Improve Human Health

Wood Frogs have attracted the attention of scientists curious about how they are able to freeze without dying. Recent research is helping determine if these methods could improve human medicine, especially in the fields of:

  • Organ Transplants: Currently the time between harvesting an organ and transplanting it is short. Being able to freeze organs without damaging the cells would allow organs to travel further to patients in need.
  • Diabetes: Before hibernation, the blood sugar level of the Wood Frog goes to 100 times its normal level with no ill effects. Scientists are studying this to see how it could help diabetes patients.
  • Strokes: Scientists are interested in how the Wood Frog’s blood stops flowing for several months without any blood clots. Understanding this could help people who have suffered from a heart attack or stroke.

The Wood Frog is not the only amphibian with an interesting hibernation process. To learn more about frogs and hibernation, check out our page on frog hibernation.

Interesting Wood Frog Facts

  • Wood Frogs recognize their family members and when they are tadpoles, siblings will group together.
  • The Wood Frogs have the furthest north range of any other North American reptile or amphibian.
  • Wood Frogs cannot determine a male from a female by sight. When it is mating season, male frogs will grab a frog to mate with and be able to tell from touch if it is female full of eggs.
  • The female Wood Frog can lay 1,000 to 3,000 eggs each breeding season.
  • Wood Frogs are diurnal, meaning they are active during the day and rest at night.
  • Male Wood Frogs generally have a shorter lifespan than female Wood Frogs.
  • The Wood Frog is the state amphibian of New York.
  • Wood Frogs are most likely to be found in wooded areas and can be found near ponds during the mating season.

Common Questions About Wood Frogs

How do wood frogs survive freezing? Wood Frogs survive freezing by developing a type of antifreeze based on glucose in their cells to prevent ice crystals from forming. Their vital organs stop during winter as they hibernate. When temperatures rise after Winter, Wood Frog are ready to mate, as if nothing unusual had happened to them.

How Often do Wood Frogs Reproduce? Wood Frogs reproduce once a year. They have one of the earliest mating seasons of all frog species. They begin breeding in early March, often before the ice has melted in the breeding ponds. The eggs transform into tadpoles a week to a month after the female lays them. 

When Can Wood Frogs Mate? Male Wood Frogs reach sexual maturity and can mate in one to two years after being born, while females reach it in three years.

What do Wood Frogs Sound Like? The Wood Frog’s croak can sound like a quacking duck or clucking chicken. Male Wood Frogs make their sounds to attract females. They will repeat the sound several times in succession to gain attention. Wood Frogs croak exclusively during the mating season

What do Wood Frogs Eat? Wood Frogs are small frogs, so their prey is also small. They favor small invertebrates like small beetles, worms, millipedes, mosquitoes and slugs. They will also eat other amphibians’ eggs. Wood frog tadpoles eat algae and plant matter.

What are the Wood Frogs’ Predators?  Many animals depend on Wood Frogs as part of their diet. Their main predators are snakes, small mammals like raccoons, skunks, and birds.

How Long do Wood Frogs Make Noise?  Wood Frogs use their croak to attract mates. This can start as early as the beginning of March and continues until the mating season is done. The Wood Frog generally doesn’t croak outside of the mating season, though they could do so to scare away a predator.

Are Wood Frogs Endangered? Wood Frogs are commonly found in the areas they inhabit. Although they are not generally considered endangered, some localities have placed them on lists of special concern as their habitat has been lost to development. Their populations can decline if breeding pools are drained or if there is deforestation.

Are Wood Frogs Poisonous? Wood Frogs are not poisonous to humans but as with all frog species, they can carry viral or bacterial diseases such as salmonella.

More About Wood Frogs

Wood Frogs are an incredible frog species that almost represent a biological miracle we still do not fully understand. With so much to offer nature and humans, Wood Frogs are essential to the ecosystems they inhabit. With a range that extends into the Arctic Circle, the Wood Frog has had to adapt to survive in extreme cold. 

Learn more about Wood Frogs in the following guides on our blog:


NPS.gov, Biological Miracle, Wood Frog