A Wonder of Winter, A Harbinger of Spring

A marvel of nature roams the woods, usually silent but for a raucous spring display. Wood frogs, Rana sylvatica, which spent the winter frozen under leaves, have started their annual concert tour of Fairfax County Park Authority forests.

Wood frogs are the only frogs that can live north of the Arctic Circle. They can withstand more than half of their body water freezing without damaging their cells because urea accumulates in their tissues and glucose forms in their livers. This is natural antifreeze that also enables the frog’s heart to cease beating and the lungs to stop breathing. The wood frogs, buried under woodland leaves instead of overwintering on muddy pond bottoms like most other frogs, can thaw and refreeze throughout the winter without harm.

Last month, males began racing to their local hangouts — ponds and vernal pools — emitting a noisy, bizarre call that resembles a laughing cartoon duck to entice the females to join them. Wood frogs are not the first amphibians you’ll hear heralding spring in our area. That honor goes to the smaller spring peeper. However, wood frogs, brown with a black eye mask and about three inches in length, are more easily seen and heard.

Wood frogs' camouflage help them blend into their surroundings.

Wood frogs’ camouflage help them blend into their surroundings.

Wood frogs commonly choose vernal pools as a breeding area because these temporary bodies of water do not host fish and turtles, which are natural predators of the frog eggs and tadpoles. At Hidden Oaks Nature Center  is a pond that is purposely kept free of fish and bullfrogs to support breeding amphibians. Each year we welcome wood frogs, followed by American toads and then spotted salamanders, to breed.

Wood frogs visit the pond to seek out a mate.

Wood frogs visit the pond to seek out a mate.

Even with a suitable site, there are difficulties finding love in the pond. During the breeding frenzy, males may mistake a male for a female or may drown the female, especially problematic for the first females to arrive on the scene. Males emit a loud croak to warn off the advances of other confused males. When the females – the silent sex – arrive, the males clasp them with their forearms in an embrace called “amplexus”. The smaller male holds onto the female until she deposits her eggs (over 1,000 of them), which usually attach to submerged plants or other egg masses.

Female wood frogs can lay over 1,000 eggs.

Female wood frogs can lay over 1,000 eggs.

After just a couple of days, breeding is complete and the parent frogs return to the forest to hunt for insects, worms and arachnids. Tucked back into the forest floor, the adults ignore their offspring and leave behind standing pools soon to be filled with hundreds of tadpoles.

Meanwhile, the egg masses develop algae which provide more oxygen for the young. The eggs in the center of the mass, warmed by the other eggs, develop faster. The warmer the water gets, the speedier the development. Within weeks, the tadpoles wriggle out of their jelly-like egg masses and develop rapidly, growing their back legs first. They scrape algae and decaying plants with a beak-like mouth. As they mature, they are omnivorous and will eat other amphibian eggs and larvae, including other wood frog larvae. Overcrowding and low temperatures can be deadly at this stage, and many tadpoles become meals for another frog, a turtle, a salamander, beetles, leeches or even an owl. Ever full of surprises, the wood frog tadpoles actually seem to recognize siblings and congregate with them. Nevertheless, the sisters and brothers are together for only a few weeks.

By June, the froglets leave the pond, unaware that they’re joining their parents in the nearby woods. About one-fifth scatter, unfortunately finding their way onto roads and, without the important skill set developed in the video game Frogger, they get squished, providing food for birds, raccoons and opossums. By the time they settle into their homes in the woods, they are virtually indistinguishable from the leaf litter. They will spend the summer finding food and trying to avoid snakes, raccoons, skunks, coyotes, foxes and birds. Wood frogs in turn hunt for snails, worms, beetles, spiders, slugs and other arthropods. They are adept hunters that can ambush their prey. Staying silent until the end of winter, wood frogs’ cacophonous duck-like chatter will again pierce the March air next year.

You’ll find wood frogs from the southern Appalachians into the boreal forests of Canada and Alaska. In late February and into March, you can see them closer to home in our own park woods and waters.

Meet some of our area’s native amphibians and maybe catch a glimpse of American toad courtship at Hidden Oaks Nature Center  as well at the county’s salute to Earth Day and Arbor Day, the April 27, 2013 Springfest at the Workhouse Arts Center in Lorton from 10 a.m. – 4 p.m.

Author Suzanne Holland is the assistant manager at Hidden Oaks Nature Center

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About Fairfax County Park Authority

HISTORY: On December 6, 1950, the Fairfax County Board of Supervisors created the Fairfax County Park Authority. The Park Authority was authorized to make decisions concerning land acquisition, park development and operations in Fairfax County, Virginia. To date, 11 park bond referenda have been approved between 1959 and 2008. Another Park Bond Referendum will be held in November 2012. Today, the Park Authority has 420 parks on approximately 23,168 acres of land. We offer 371 miles of trails, our most popular amenity. FACILITIES: The Park System is the primary public mechanism in Fairfax County for the preservation of environmentally sensitive land and resources, areas of historic significance and the provision of recreational facilities and services including: o Nine indoor RECenters with swimming pools, fitness rooms, gyms and class spaces. Cub Run features an indoor water park and on-site naturalist. o Eight golf courses including Laurel Hill, our newest, upscale course and clubhouse located in Southern Fairfax County o Five nature and visitor centers. Also seven Off-Leash Dog Activity areas o Several lakes including Lake Fairfax, Lake Accotink and Burke Lake, with campgrounds at Burke Lake and Lake Fairfax o The Water Mine Family Swimmin’ Hole at Lake Fairfax, Our Special Harbor Sprayground at Lee as well as an indoor water park at Cub Run RECenter o Clemyjontri Park, a fully accessible playground in Great Falls featuring two acres of family friendly fun and a carousel o An ice skating rink at Mount Vernon RECenter and the Skate Park in Wakefield Park adjacent to Audrey Moore RECenter o Kidwell Farm, a working farm of the 1930s era at Frying Pan Farm Park in Herndon, now with historic carousel o Eight distinctive historic properties available for rent o A working grist mill at Colvin Run in Great Falls and a restored 18th century home at Sully Historic Site in Chantilly o A horticulture center at Green Spring Gardens in Annandale o Natural and cultural resources protected by the Natural Resource Management Plan and Cultural Resource Plans, plus an Invasive Management Area program that targets alien plants and utilizes volunteers in restoring native vegetation throughout our community o Picnic shelters, tennis courts, miniature golf courses, disc golf courses, off-leash dog parks, amphitheaters, a marina, kayaking/canoeing center o Provides 274 athletic fields, including 30 synthetic turf fields, and manages athletic field maintenance services at 500 school athletic fields PARK AUTHORITY BOARD: • A 12-member citizen board, appointed by the Fairfax County Board of Supervisors, sets policies and priorities for the Fairfax County Park Authority. Visit http://www.fairfaxcounty.gov/news2/social-hub/ for Fairfax County Government's Comment Policy.

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