Creature Feature: Wood Frog (Rana sylvatica)
By Emma Dean, CG Science Editor
Wood frogs are native to North America, found both the United States and Canada. The creature is less than picky about its habitat and can be observed in all sorts of areas such as tundras, thickets, damp meadows, bogs and both coniferous and deciduous forests. However, in order to breed, wood frogs require aquatic areas, preferably without the presence of fish which pose a predatory threat for the eggs and larvae.
Breeding begins during late winter to early spring. The males emit a sound similar to a squawking duck because gender is impossible to determine by sight alone. In order to lay and fertilize, the male grips the female in a manner that resembles an amphibian Heimlich Maneuver. The female frog, fat with eggs, will release the eggs and then the male will fertilize the mass and surrounding water with sperm. If a male intent on mating accidentally embraces another male, the wrongly sought after male will croak loudly. A female who has already mated will be thin and let go by a male upon the realization that she has no more eggs to discharge.
The 1,000 to 3,000 eggs dispersed depend on the temperature of the water in order to hatch. Eggs in colder waters may take up to a month to hatch while eggs in warmer waters may hatch in a mere 10 to 14 days.
Once hatched, the tadpoles are provided with a nutritious yolk sac, similar to the yolk in a bird’s egg. The parental duties of the wood frog are nonexistent as the parents do nothing after the initial fertilization.
- Wood frogs are the only frogs found north of the Arctic Circle.
- Males reach breeding maturity between one and two years of age while females reach maturity between two and three years.
- The population decline of any type of amphibians is of concern and so the wood frog is an indicator of environmental health.
- The coloration of the wood frog ranges from variations of brown, tan, green and grey. Some discovered have been reddish in color or pink.
- Due to suburban sprawl and agricultural development, the wood frog has been listed on the list of species of special concern in some areas despite a breeding period often described as explosive.
- Wood frogs hibernate during the winter and can actually freeze if the weather is cold enough and then thaw out and become active when the weather warms.
- Food of choice for the wood frog includes spiders, beetles, moth larvae, slugs, snails, algae as well as the eggs or larvae of other amphibians.
- As far as predators, wood frogs may be hunted by creatures such as larger frogs and water snakes.