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Frogs Are A Sure Sign of Spring, But That Doesn't Mean You Won't Hear Them Now


The diminutive Pacific Tree Frog. Photo by Mike Sevon via U.S. Fish and Wildlife Service.

If you want to know whether Spring is on the way, don’t look to groundhogs for the answer. Instead, listen for the frogs.

Certain species of frogs, such as the wood frog, begin singing even when there is still snow on the ground. They interpret cues from nature, including slight rises in temperature, that it’s time to travel to vernal pools and ponds and begin breeding. At the breeding sites, huge numbers of frogs sing to attract mates and the sound can be deafening. Puxataneuny Phil often gets things wrong, but a chorus of spring peepers rarely misses the mark on spring.

Before you head to the parks, take a few minutes to learn more about three common early spring frogs. If you want to hear the different frog calls, visit

Wood Frogs (Rana sylvatica):

Found in Rocky Mountain National Park, Denali National Park and Preserve, Great Smoky Mountains National Park, Lake Clark National Park and Preserve and elsewhere.

Wood frogs are one of the most amazing animals in nature. Not only can they freeze their entire body, but they also stop their heart beat for days and weeks at a time!

In the late fall, wood frogs bury themselves under leaf litter and prepare for winter. The frog moves water from the vital internal organs and into open spaces of the body where it freezes. The rest of the body survives by having a natural sugar-based anti-freeze pumped into the cells. At the end of the process, the wood frog is more dead than alive. But come Spring, it takes the frog less than a day to completely defrost, come alive and prepare to breed.

By being close to the surface and freezing itself, wood frogs can survive in very cold places, such as Alaska, and they are one of the first frogs to emerge and breed.

Wood frogs call with a quacking sound, almost like a duck. They are about 1½ to 3 inches in length. The most noticeable features of the wood frog are the black “mask” that runs across the mouth and the two ridges down the back.

The range of the wood frog includes the northeastern United States and Alaska. They are very common in Alaska. Wood frogs breed in temporary vernal pools in early spring.

Spring Peepers (Pseudacris crucifer):

Found in Great Smoky Mountains National Park, Acadia National Park, Cuyahoga Valley National Park, Shenandoah National Park, Isle Royale National Park and elsewhere.

If you look closely at a spring peeper, you’ll realize how the frog got its scientific name. They are small frogs, less than 1½ inches long. A black 'X' covers the spring peeper’s tan back, and from many angles it looks like a cross. Along with its song, the 'X' is one of the main identifying characteristics of the spring peeper.

Spring peepers sing with loud, “preep” whistle. A chorus of spring peepers sounds like jingling bells.

Spring peepers emerge from their winter hibernation in early January to early April depending on where you live. The farther south, the sooner they are heard. Spring peepers breed in ponds, marshes, swamps and temporary pools. Listen for spring peepers throughout the eastern half of the United States.

Pacific Treefrogs (Pseudacris regilla):

Found in North Cascades National Park, Channel Islands National Park, Redwood National Park, Olympic National Park, Crater Lake National Park and elsewhere.

Pacific treefrogs call so early in spring, they are sometimes heard in December in California. Depending on your location, Pacific treefrogs can sing from late December until August. They’ll even call during the day, making the Pacific treefrog one of the most heard and well-known amphibians in the western United States.

The Pacific treefrog is one of the rare frog species that actually calls with a “ribbit”. The two-part musical song, became the most familiar frog call, because Pacific treefrogs were often recorded as background noise in movies. Even people who have never been to the West Coast know the call of the Pacific treefrog.

Pacific treefrogs are about 1 to 2 inches long with sticky toe pads used for climbing. They can be a variety of colors including green, gray, tan or brown. The most noticeable characteristics of the Pacific treefrog are two dark markings on the face. The first marking is a brownish-black line that runs from the shoulder through the eyes. The second marking is a dark triangle shape on the back of the head.

The range of the Pacific treefrog extends from southern California to British Columbia and east to Nevada. Despite being a treefrog, Pacific treefrogs are often found on the ground or on low vegetarion. They breed in ponds and vernal pools, especially in areas with no fish to prey on the young. In the non-breeding seasons, Pacific treefrogs venture far from ponds to wet meadows, streams, and even your backyard. They will go wherever it is damp!

Traveler trivia, two bits:

Technological breakthroughs have resulted in the development of tiny (.61 g) radio transmitters. Radio collars have long been used to understand the habitat use and movements of larger animals such as elk, bears, and bighorn sheep. Radio telemetry is a relatively new tool for studying frogs.

Since frogs don’t really have necks to hold a collar, the radio transmitters are attached to a “belt” consisting of fine elastic thread strung with green glass beads. The “inventor” of the wood frog radio belt, Dr. Erin Muths, first experimented with the belts on captive frogs in her Fort Collins lab (Dr. Muths is a scientist with the U.S. Geological Survey.) After the experimental collars were put on, the animals were checked frequently for behavior changes, weight loss, or injuries. After Dr. Muths was satisfied that the transmitter assembly (belt, radio transmitter, antenna) was safe she submitted records of her experiment to the USGS Animal Care and Use Committee for review. Such committees provide oversight of animal handling and marking techniques. Rocky Mountain National Park requires this type of independent review before issuing a research permit.

The belts were first deployed on park wood frogs in 2003. Wood frogs are of interest because their park population is disjunct (separated in space) from other populations. They occur in Canada, the eastern U.S., in a limited area in Colorado, and in one small population in Wyoming. While other frogs species have been ravaged by disease and mysterious disappearances, wood frogs seem to be holding their own.


Thanks for the post Jessica. I've been hearing frogs all winter here in the foothills of the Sierra.

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