Green Frog (Lithobates clamitans)
Order Anura, Family Ranidae, Genus Lithobates, Species Lithobates clamitans
Species
Green Frog (Lithobates clamitans)
Family
Order Anura, Family Ranidae, Genus Lithobates, Species Lithobates clamitans
Size
Adult green frogs typically range from 2.1 to 3.5 inches (5.5 to 9 cm) in snout-to-vent length (SVL). Females are generally slightly larger than males, though males have significantly larger tympanums compared to their eye size. Weight typically ranges from 30 to 80 grams depending on age and sex.
Conservation
IUCN Red List status is Least Concern, with a stable population trend. They are adaptable and common across much of their range, though local populations can be impacted by habitat destruction, pollution, and the amphibian chytrid fungus.
Description
The green frog is a quintessential inhabitant of eastern North American wetlands. With its bright green upper lip, striking golden eyes, and banjo-like call, it brings life to ponds and marshes. Sitting quietly amongst lily pads, it waits patiently for passing prey, ready to launch into the water with a characteristic splash at the slightest disturbance.
Key Features
Prominent dorsolateral folds extending partially down the back (not reaching the groin), large tympanum relative to the eye, bright green upper jaw and snout contrasting with a darker body, and extensive webbing on the hind feet.
Physical Description
The green frog has a stout, robust body with a distinct, somewhat pointed head. Its eyes are prominent with horizontal pupils and a golden-brown iris. A noticeable tympanum (eardrum) is visible just behind the eye, which is larger in males than in females. The hind legs are long and powerful, designed for leaping, while the front legs are short and sturdy. The toes are extensively webbed, though the tips are simple without expanded toe pads. A pair of prominent dorsolateral folds runs from behind the eyes down the back, stopping short of the groin.
Skin Texture & Coloration
The skin is generally smooth on the back, sometimes becoming slightly granular on the flanks and posterior. The coloration is highly variable, ranging from bright green to olive-brown or dark brown, often fading to a paler yellowish-green on the head and shoulders. Dark spots or blotches are frequently scattered across the back, and the limbs often feature dark banding. The venter is white or yellowish, sometimes with dark mottling on the throat, particularly in breeding males who may develop a bright yellow throat.
Distinguishing Features
The key distinguishing feature of the green frog is the presence of a pair of dorsolateral folds that extend down the back but do not reach the groin. This separates it from the bullfrog, which lacks dorsolateral folds entirely, and the pickerel/leopard frogs, which have folds that reach the posterior end. Additionally, the relatively large tympanum and the bright green coloration around the head and upper lip help confirm its identity.
Habitat
Green frogs are semi-aquatic and are closely associated with permanent freshwater habitats such as ponds, marshes, swamps, lake edges, and slow-moving streams. They prefer areas with abundant emergent vegetation and muddy substrates where they can easily submerge or hide. They are generally found at low to moderate elevations.
Geographic Range
Native to eastern North America, ranging from southern Canada down through the eastern United States to the Gulf of Mexico, extending westward to the Great Plains. They have also been introduced to certain areas outside their native range, such as parts of western North America and British Columbia.
Behavior
Green frogs are primarily active both day and night (diurnal and nocturnal), though they are most frequently heard calling during late spring and summer. They are strong jumpers and will quickly leap into water when startled, emitting a startled squeak. They are largely solitary outside of the breeding season and are territorial during peak breeding times.
Diet & Feeding
As carnivorous generalists, green frogs feed on a wide variety of invertebrates including insects, spiders, worms, snails, and small crustaceans. Larger adults will also consume small vertebrates such as fish, tadpoles, other frogs, and small snakes. They use a sit-and-wait ambush strategy, snapping up passing prey with a sticky, projectile tongue.
Reproduction
Breeding occurs from late spring through late summer, triggered by rising water temperatures and heavy rains. Males establish territories near the water's edge and call to attract females. Amplexus is axillary. Females lay large surface films or masses containing anywhere from 1,000 to 4,000 eggs attached to submerged vegetation. There is no parental care once eggs are laid.
Vocalizations
The advertisement call of the green frog is famously described as sounding like a loose banjo string being plucked (a single, sharp 'guck' or 'twang'). Calls can be given singly or in short series, often increasing in tempo. Males also emit a distinct release call when clasped by another male.
Life Cycle
Eggs hatch within a few days to a week depending on water temperature. The tadpole stage lasts anywhere from two to twelve months, with some individuals overwintering as tadpoles before undergoing metamorphosis the following summer. Juveniles resemble miniature adults and reach sexual maturity within one to two years. Total lifespan in the wild is typically 4 to 6 years.
Conservation Status
IUCN Red List status is Least Concern, with a stable population trend. They are adaptable and common across much of their range, though local populations can be impacted by habitat destruction, pollution, and the amphibian chytrid fungus.
Toxicity & Defense
Green frogs are non-toxic to humans. Their primary defense mechanisms are rapid leaping into deep water to escape predators, cryptic coloration, and defensive vocalizations or startle leaps.
Ecological Role
As both predator and prey, green frogs play a crucial role in freshwater food webs. They help control insect and invertebrate populations while serving as an essential food source for wading birds, snakes, larger fish, and mammals.
Similar Species
American Bullfrog (Lithobates catesbeianus) lacks dorsolateral folds entirely. Southern Leopard Frog (Lithobates sphenocephalus) and Pickerel Frog (Lithobates palustris) have dorsolateral folds that continue all the way to the groin, and distinct spots arranged in rows or patterns.
Observation Tips
The best time to observe green frogs is during warm summer days or nights near the edges of ponds and slow streams. Look for them sitting motionless along the shoreline or partially submerged among aquatic plants. Approach slowly and quietly to avoid startling them into the water.
Handling & Safety
Green frogs are harmless to humans and do not possess toxins. If handling is necessary for relocation or study, hands should be thoroughly rinsed of all soaps, lotions, and insect repellents, and kept wet to protect the frog's sensitive skin. Minimize handling time to reduce stress on the animal.
Seasonal Activity
Green frogs are active from spring through autumn. As temperatures drop in late autumn, they migrate to the muddy bottoms of ponds and slow streams, where they undergo brumation (hibernation) underwater, absorbing oxygen through their skin until spring arrives.
Cultural Significance
Green frogs are familiar backyard pond residents and frequently appear in children's literature, nature documentaries, and folklore regarding wetland wildlife. They serve as an important cultural symbol of healthy aquatic ecosystems.
Interesting Facts
The green frog is famous for its pluck-like banjo call. Unlike many other frogs that call only in a brief explosive burst in early spring, green frogs have an extended breeding season and can be heard calling throughout the entire summer.