Species Fact Profile: Wood Frog (Lithobates sylvaticus)

                                                                     Wood Frog

Lithobates sylvaticus (LeConte, 1825)

Range: Alaska, Canada, northeastern United States)

Habitat: Freshwater Wetlands, Moist Woodlands

Diet: Small terrestrial invertebrates (beetles, slugs, spiders).  Tadpoles eat algae

Social Grouping: Solitary

Reproduction:  Breeds in temporary seasonal pools early in the spring.  Female deposits eggs on objects at the bottom of the pool, forming large masses of 1000-3000 eggs.  Eggs laid in warmer water hatch faster than eggs in cooler water (difference of 10-14 days versus one month).  Tadpoles metamorphose into adults at 2-4 months post hatching.  Males sexually mature at 1-2 years, females at 2-3 years.

Lifespan: 3-5 Years

      Conservation Status: IUCN Least Concern

• Body length 5-7 centimeters, weigh about 8 grams (females larger than males)
• Brown, tan, or rust-color on the back, pale yellow or green on the underside.  Characteristic black robber mask stripe across the eyes, white outline around the lips
• Males and females cannot distinguish each other by sight.  Instead, courting males will hop on top of strange frogs and embrace them.  If the frog they are holding does not feel large enough to be a female full of eggs, they will let go and search for another.  If a male is grabbed by another male, he will croak to let the other frog know
• One of the most cold-tolerant of frogs, and one of the first to emerge in the spring, even before the snow has melted.  Enter dormancy in winter, burrowing in the soil or leaf litter.  Capable of tolerating some freezing of blood and body tissues (up to 65% of their body water can freeze).  Their body produces a natural antifreeze to prevent cell damage
• Predators include larger frogs, snakes, herons, and small mammalian carnivores (raccoons, skunks, etc).  Beetles and other tadpoles may eat wood frog tadpoles.  Adults rely on camouflage to protect them from predators; also have skin secretions, but not especially potent ones
• Not yet endangered, but in decline due to loss of habitat (especially breeding pools), contamination of freshwater ecosystems through road salt and other pollutants