Wood Frog

Wood Frog

Eastern Wood Frog, Swamp Frog, Masked Frog, Forest Frog

Lithobates sylvaticus

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The North American wood frog (Lithobates sylvaticus, formerly known as Rana sylvatica), is a small, terrestrial frog species native to North America. It is found across a wide range of regions, including the United States, Canada, and parts of Alaska.  The North American wood frog has unique adaptations that allow it to thrive in many habitats, including cold climates. Its ability to endure freezing temperatures and survive the winter months in a frozen state makes particularly interesting to scientists who study cryonics, which has to do with preserving humans and animals in a frozen state for long periods of time.

Wood Frog

Common Name
Wood Frog

Other Names

Eastern Wood Frog, Swamp Frog, Masked Frog, Forest Frog

Latin Name

Lithobates sylvaticus

Distribution

YK, NWT, NU, BC, AB, SK, MB, ON, QC, NB, NS, PEI, NL

Appearance

Wood frogs have a compact body with a rounded snout and prominent eyes. They commonly exhibit shades of brown, gray, or reddish-brown. They have a dark-colored mask-like marking that extends from the eyes to the eardrums.

Size

1.5 to 2.75 inches (3.8 to 7 centimeters) in length.

Habitat

They inhabit various terrestrial and semi-aquatic habitats, including forests, woodlands, wetlands, bogs, and meadows.

Behavior

Unique breeding behavior called ‘explosive breeding’ where wood frogs gather in very large numbers at breeding sites like temporary ponds, and lay thousands of eggs within a short time frame.

Diet

Wood frogs consuming a variety of invertebrates like small insects, spiders, worms, and other arthropods. Tadpoles feed on algae and other organic matter.

Lifecycle

Typical from lifecycle. Eggs are laid in the water. After breeding, wood frogs leave the water and return to their terrestrial habitat.

Vocalization

Males produce a duck-like quacking call during mating season to attract females.

Conservation Status

Widespread and abundant. Listed as ‘least concern’ by the International Union for the Conservation of Nature

Appearance: Wood frogs have a relatively compact body with a rounded snout and prominent eyes. They are typically small, measuring around 1.5 to 2.75 inches (3.8 to 7 centimeters) in length. Their skin coloration varies, but they commonly exhibit shades of brown, gray, or reddish-brown. They may also have darker patches or irregular markings on their body. A distinguishing feature of wood frogs is a dark-colored mask-like marking that extends from the eyes to the eardrums.

Range and Habitat: North American wood frogs are found across a broad geographical range. They inhabit various terrestrial and semi-aquatic habitats, including forests, woodlands, wetlands, bogs, and meadows. They are well adapted to withstand colder climates and can be found in northern regions where other frog species may not survive.

Breeding Behavior: Wood frogs exhibit an interesting breeding behavior. During the spring, as temperatures rise and snow melts, male wood frogs gather at breeding sites, such as ponds or vernal pools. They produce a distinct advertisement call, described as a duck-like quacking sound, to attract females. Mating occurs in the water, where females deposit eggs that are externally fertilized by males. After breeding, wood frogs leave the water and return to their terrestrial habitat.

Freezing Tolerance: One of the most remarkable aspects of the wood frog is its ability to survive freezing temperatures. As winter approaches, wood frogs undergo an incredible adaptation known as freeze tolerance. They can withstand the freezing of a significant portion of their body fluids and even their organs. They do this by producing high concentrations of glucose and other substances that act as cryoprotectants. These cryoprotectants prevent ice formation within the frog’s cells, protecting them from damage. When spring arrives, the wood frogs thaw out and resume their normal activities.

Diet: Wood frogs are opportunistic feeders, consuming a variety of invertebrates. Their diet primarily consists of small insects, spiders, worms, and other arthropods that they find in their terrestrial habitat. Tadpoles, during their aquatic stage, feed on algae and other organic matter present in the water.

Conservation Status: The North American wood frog is considered a species of least concern in terms of conservation. However, like many amphibians, they can be susceptible to habitat loss, pollution, and other environmental factors. Efforts are made to protect their natural habitats and ensure the continued survival of their populations.

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