Frogs

A pickerel frog hiding in a grassy area next to a pond.

NPS / R.Wang

Frogs range from a variety of sizes and colors. Did you know that all toads are frogs, but not all frogs are toads? Both frogs and toads are categorized under the order Anura. The difference is that frogs can be classified under a variety of families (according to the scientific classification structure), but toads only belong to the family Bufonidae. Frogs typically have smooth and moist skin whereas toads have dry, warty, bumpy skin. There are nine frogs native to Maine and found within the boundaries of Katahdin Woods and Waters National Monument.

Frogs will eat whatever they can fit in their mouths, including small frogs and rodents. However, frogs typically feed on insects, worms, spiders, and slugs. Each species has a unique call and can be heard loudly during mating season. The best areas to observe frogs are near wetland habitats.

If you come across a frog in the wild, it’s best to avoid handling it and to enjoy the moment by observing it from a distance. If you are visiting during the spring, you can stand still near wetland areas and listen to their songs and calls when they are trying to attract mates. Please share photos through iNaturalist. We would love to see your observations!

Maine Department of Inland Fisheries & Wildlife encourages members of the public to share their photo-documented observations as part of the Maine Amphibian & Reptile Atlas Project (MARAP) to help researches and scientists learn about the distribution and ecology of Maine’s herpetofauna (the reptiles and amphibians of a particular region).

 

Green frog next to a pond.

NPS / Grace Kirk

Green Frog

(Lithobates clamitans)

• Green or greenish-brown in color above with a light underside. Dark gray or brown bars pattern the hind legs.

• Approximately 2–4 inches in length.

• A prominent ridge starts from behind their eyes to near their groin.

• Feeds on anything it can catch, including invertebrates, fish, snakes, or frogs. They are aggressive predators.

• Hibernates underground or underwater during the winter.

 

Gray treefrog

NPS / K. Stauffer

Gray Treefrog

(Hyla versicolor)

• Juveniles are lime green in color, but most adult gray treefrogs are gray and speckled in color and have rough and warty skin.

• Approximately 1.5–2 inches in length.

• They feed on mostly insects, but adults may feed on smaller frogs.

 

American toad

NPS / Sarah King

American Toad

(Bufo americanus)

• Shades of brown, dark brown, or reddish brown in color with rough, spotted, and warty skin.

• Approximately 2–4.5 inches.

• May burrow under soil to stay cool during hot weather.

• Has glands behind their eyes that produce toxins on their skin.

• Feeds on insects, slugs, spiders, and worms.

• Lay eggs in long parallel strands (between 4,000–12,000 eggs).

• Hibernate during the winter under soil or leaf litter.

 

American Bullfrog

NPS / Sarah King

American Bullfrog

(Rana catesbeiana)

• The American bullfrog is the largest North American frog. It has been documented to grow up to 8 inches long!

• Shades of green in color with dark brown spots. Their bellies range from colors of yellow to white. They have glandular folds, pronounced ridges that wraps around the tympanum (a thin membrane covering its organ for hearing). Bullfrogs have pointed toe tips and webbed hind feet.

• Territorial and aggressive. Lives in permanent aquatic areas with shallow slow-moving waters, like ponds and lakes.

• Breeds later than other frogs in Maine, typically late spring, or early summer.

• They have a great appetite and are opportunistic predators. They will ambush and attack any live smaller animals in relation to themselves. However, they typically eat insects, invertebrates, fish, snakes, or other frogs.

• Native to eastern North America. areas from Nova Scotia to central Florida to the Great Plains, but are considered invasive species in western states.

 

Wood frog

NPS / Grace Kirk

Wood Frog

(Rana sylvatica)

• Known for their black marking across the eyes (it looks like a mask). Wood frogs vary in shades of brown, red, and gray.

• Widely distributed in forests of North America (northern Georgia to north of the Arctic Circle in Alaska and Canada).

• 1.5–2.5 inches long.

• Breeds in vernal pools in the beginning of spring.

• Typically feeds on insects.

• Produces toxins as a defense mechanism.

• Wood frogs have an ability to freeze and thaw with winter and spring patterns. Yes, their heart and brain activity stops! Scientists and researchers are looking into this incredible winter adaptation to learn more.

 

Pickerel frog

NPS / R.Wang

Pickerel Frog

(Lithobates palustris)

• Light brown in color with two parallel rows of large, square or rectangular shaped spotted patterns on their back between prominent ridges. Has a short blunt snout.

• Approximately 2–3 inches in length.

• Found in aquatic areas with dense vegetation (wet woods, damp or wet fields and meadows, and shores of lakes, ponds, and streams).

• Eats mostly insects, spiders, and invertebrates.

 

Leopard frog

NPS / R.Wang

Northern Leopard Frog

(Lithobates pipiens)

• Green or brown with dark rounded spots with thin light green borders on its back. Its underside is white or light gray. They have prominent ridges along both sides of its back that run from its eyes to its groin.

• Approximately 2–3.5 inches long.

• Feeds on invertebrates, spiders, mollusks, and crustaceans.

• Can be found in grasslands and areas of slow-moving water or permanent or temporary pools of water (ponds and lakes).

• During the winter, they hibernate underwater in ponds, lakes, or deep streams to do not freeze.

• Northern leopard frogs have been experiencing significant declines, especially in the western two-thirds of the United States and Canada.

 

Mink frog

NPS / Anne Longman

Mink Frog

(Lithobates septentrionalis)

• Dark green or olive in color with irregular mottled-blotchy dark patterning along the back and hind legs. A distinctive characteristic to help identify the mink frog from the green frog is their webbed hind toes. The webbing extends up to the last join of the 4th toe and to the tip of the 5th toe.

• Approximately 3 inches long.

• Found in the northeast region, from Minnesota to Maine. Central New York is the southern limit of the mink frog. They are also found in eastern Canada.

• Mink frogs live in or near cold permanent ponds and lakes with floating vegetation, like lily pads in forested areas. They are highly aquatic.

• Feeds on insects, small invertebrates, spiders, beetles, and slugs.

• Breeds later in spring and into summer.

• Skin produces a musky odor when handled.

• During the winter they hibernate underwater.

 

Spring peeper

NPS / R.Wang

Spring Peeper

(Pseudacris crucifer)

• The smallest frog in Maine. Only approximately 0.8–1.5 inches long.

• Has smooth and moist skin. Light gray to light brown in color with a dark “x” marking on their back.

• Their call is a high-pitched “peep,” typically heard early spring when they mate. Only males have an expanding vocal sac under their chin when making their calls. They are one of the earliest frogs to mate when temperatures begin to warm. People often associate their high pitched call with the arrival of spring.

• Feeds on small insects, snails, and spiders.

• Spring peepers are native to eastern North America.

• Found in wooded areas near ponds, marshes, and wetland areas. Remember to look up! Spring peepers spend their time up in trees and other vegetation.

• Hibernates during the winter under logs, leaf litter, and bark. They can even partially freeze during the winter and thaw when spring arrives!