The green frog (Lithobates clamitans) is a common amphibian across eastern North America. Its widespread presence makes it a familiar sight in various aquatic environments, often signaling a healthy freshwater ecosystem. It plays a role in the ecosystem of ponds, lakes, and other watery habitats.
Green Frog Identification
Green frogs are medium-sized amphibians, measuring 5 to 10 cm (2 to 4 inches) in body length. Their coloration varies, ranging from bright green to olive, brown, or even bronze, sometimes with darker spots on their backs and legs. A distinguishing feature is prominent dorsolateral folds, seam-like skin ridges extending from behind their eyes partway down their backs. These folds differentiate them from similar species like the bullfrog.
The head of a green frog is greener than its body, and the belly is white, sometimes with dark mottling or a yellow tinge. Male green frogs can be identified by their bright yellow throats and eardrums (tympanums) that are larger than their eyes. In contrast, female tympanums are about the same size as their eyes.
Green Frog Habitat
Green frogs are aquatic and thrive in a variety of freshwater habitats. They inhabit the margins of shallow ponds, lakes, marshes, swamps, slow-moving streams, and roadside ditches. They prefer environments with ample aquatic vegetation and shoreline cover, which provide shelter and hunting grounds.
The presence of aquatic plants like sedges, cattails, and rushes provides crucial habitat. They spend most of their time along these watery edges, hunting for prey and quickly retreating into the water if threatened. While primarily aquatic, juveniles may use upland areas during rainy periods, and adults can occasionally forage away from large bodies of water.
Green Frog Diet
Green frogs are carnivorous predators, eating any mouth-sized animal they can capture. Their diet primarily consists of insects (flies, beetles, crickets, moths, spiders). They also eat other invertebrates like slugs, snails, and crayfish. Larger individuals may occasionally eat small snakes, other frogs, or even their own tadpoles.
These frogs employ a “sit-and-wait” hunting strategy. They remain still near the water’s edge or in vegetation, waiting for prey to come within reach. Once prey is close, the frog uses its sticky tongue to quickly snatch it.
Green Frog Life Cycle
The life cycle of a green frog involves complete metamorphosis, beginning with eggs laid in water. Breeding occurs from spring through summer, between May and August, depending on region and temperature. Females lay a large clutch of 1,000 to 7,000 eggs in a thin, film-like mass on the surface of shallow water, often attached to vegetation.
These black eggs, encased in a jelly-like substance, hatch within 3 to 7 days. Hatched tadpoles are aquatic, olive-green with dark spots, and initially feed on algae and other organic matter. Tadpoles take a few months to over a year to develop, with many overwintering before transforming. During metamorphosis, tadpoles grow limbs, their tails absorb, and they develop lungs for breathing air, emerging as small froglets. Young frogs reach sexual maturity one to two years after metamorphosis.
Green Frog Conservation
Green frogs are considered common and widespread throughout their native range in eastern North America. The International Union for Conservation of Nature (IUCN) lists them as a species of “Least Concern.” However, localized populations can face various threats.
Habitat loss and degradation, particularly the destruction of wetlands and shoreline areas, threaten green frog populations. Pollution, including pesticides and herbicides, also impact these amphibians, as their permeable skin makes them sensitive to environmental contaminants. Protecting their aquatic habitats and reducing pollution support green frog populations and ecosystem health.