The Green Frog (True Frog Family)

The Green Frog (Rana clamitans) is usually found near shallow fresh water throughout much of eastern North America. Order Anura, Family Ranidae. These are typical frogs with adults being truly amphibious, living at the edge of water bodies and entering the water to catch prey, flee danger, and spawn. This profile covers medium-sized ranids. Also, all frogs are somewhat poisonous to some degree, but most of them aren’t harmful to humans.

Description

Two subspecies are recognized: R. c. clamitans (the bronze frog; ranges from the Carolinas to northern Florida, west to eastern Texas, and north along the Mississippi Valley to the mouth of the Ohio River).

However, the R. c. melanota (the green frog; ranges from southeastern Canada to North Carolina, west to Minnesota and Oklahoma but rare in much of Illinois and Indiana, introduced into British Columbia, Washington, and Utah.

Body Size

The green frog is a medium-sized ranid usually between 5.7 and 8.9 cm snout-to-vent length. Its growing period is mainly confined to the period between mid-May and mid-September. But the females are generally larger than males. But the adults typically weigh between 30 and 70 g. The average lifespan of the Green Frog is approximately 16 years, fairly long compared with other frogs.

Green Frog Habitats

Adult green frogs live at the margins of permanent or semi-permanent shallow water, springs, swamps, streams, ponds, and lakes. Green frogs primarily inhabitant the banks of streams. They also can be found among the rotting debris of fallen trees. Juveniles prefer shallower aquatic habitats with denser vegetation than those preferred by adults.

Moreover, Green frogs inhabited aquatic habitats about two-thirds of the time and terrestrial habitats the remaining time. The green frog relies on terrestrial habitats for feeding and aquatic habitats for refuge from desiccation, temperature extremes, and enemies. Ponds used by green frogs are usually more permanent than those used by other anuran species.

Green Frog Food

Adult R. clamitansare terrestrial feeders among shoreline vegetation. They consume insects, worms, small fish, crayfish, other crustaceans, newts, spiders, small frogs, and molluscs. The terrestrial beetles often are their most important food item but noted that any locally abundant insect along the shoreline may be consumed in large numbers.

There is a pronounced reduction in food consumption during the breeding period for both males and females. During the breeding season, males spend most of their energy defending breeding territories, and

Green Frog females expend their energy-producing eggs. Fat reserves acquired during the rebreeding period compensate for reduced food intake during the breeding period. Also, green frogs consume most of their food in the spring and eat little during the winter. Food is eaten in the spring, summer, and fall and consists mostly of terrestrial prey.  whereas winter food is composed mostly of aquatic prey.

Juveniles (sexually immature frogs) eat about half the volume of food as do adults over the course of a year. Green frogs eat their cast skins following molting; the casting of skin is frequent during midsummer.

Temperature regulation and daily activities. Green frog’s activity period varies by frog size, with larger frogs being primarily nocturnal, small frogs being diurnal, and middle-sized frogs (5 to 7 cm SVL) being equally active during day and night.

Hibernation

Adult green frogs overwinter by hibernating underground or underwater from fall to spring. The frogs hibernate in mud and debris at the bottom of streams approximately 1 m deep. The adults usually hibernate in restricted chambers within rock piles or beneath plant debris, while juveniles are more often found in locations with access to passing prey.

The frogs begin emerging when the mean daily temperature is about 4.4C and the maximum temperature is about 15.6C for 3 to 4 days. Juvenile frogs enter and exit hibernation after adult frogs.

Breeding Activities and Social Organization

Green frogs breed from spring through the summer, spawning at night. Female green frogs stay in a nonbreeding habitat until it is time to spawn. In preparation for breeding, males establish territories near the shore that serve as areas for sexual display and as defended oviposition sites.

Males establish calling sites within their territories where they attempt to attract females. Females visit male territories to mate and lay their egg masses. The masses are contained in films of jelly and are deposited in emergent, floating, or submerged vegetation; they hatch in about 3 to 6 days. Adults are solitary during non-breeding periods.

In the southern part of their range, green frog tadpoles metamorphose into frogs in the same season in which they hatched, while in the northern part, 1 or 2 years pass before metamorphosis. Tadpoles that hatch from egg masses laid in the spring usually metamorphose that fall, while those hatching from summer-laid eggs typically overwinter as larvae and metamorphose the following spring. 

Most tadpoles are 2.6 to 3.8 cm SVL at the time of transformation. Those that transform in late June or early July grow rapidly, adding 1.4 to 2.0 cm SVL in the first 2 months and 0.4 to 0.7 cm SVL more before hibernation. Tadpoles that transform at approximately 3.1 cm SVL may reach between 5.0 and 5.8 cm SVL before hibernation. Therefore, newly transformed frogs often move from lakes and ponds where they were tadpoles to shallow stream banks, usually during periods of rain.

Home Range

The species’ home range includes its foraging and refuge areas in and around aquatic environments. During the breeding period, the male’s home range also includes its breeding territory. It is roughly 80 percent of adult frogs captured in the spring and again in the fall occupied the same home ranges.

Population Density

During the breeding season, green frog densities at breeding ponds can exceed several hundred individuals per hectare. Adult male frogs space their breeding territories about 2 to 3 m apart.

Sexual maturity is attained in 1 or 2 years after metamorphosis; individuals may reach maturity at the end of the first year but not attempt to breed until the next year. Most females lay one clutch per year, although some may lay two clutches, about 3 to 4 weeks apart. In natural populations, green frogs can live to approximately 5 years of age.

Similar Species

1. The river frog (Rana heckscheri) is slightly larger than the green frog (8.0 to 12.0 cm SVL) and is found in swamps from southeast North Carolina to central Florida and southern Mississippi.

2. The leopard and pickerel frogs (Rana pipiens and its relatives, and Rana palustris) are medium-sized and strongly spotted. There are four leopard frogs whose ranges are mostly exclusive from each other but overlap with the green frog. The pickerel frog has a similar range with gaps in the upper Midwest and the southeast.

3. The mink frog (Rana septentrionalis) is only slightly smaller (4.0 to 7.0 cm) and is found on the borders of ponds and lakes, especially near waterlilies. It ranges from Minnesota to New York, north to Labrador.

4. The carpenter frog (Rana virgatipes) is about the same size as the green frog (4.1 to 6.7 cm) and is closely associated with sphagnum bogs and grasslands. It has a coastal plain ranging from New Jersey to Georgia and Florida. The bullfrog and pig frog are much larger ranid species.

   

   

   

   

   

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