Rana clamitans

Lithobates clamitans or Rana clamitans, commonly known as the green frog, is a species of frog native to eastern North America. The two subspecies are the bronze frog and the northern green frog.

These frogs typically have varying degrees of green heads, as their name suggests. These frogs display significant acts of territoriality, with males being the primary actors. Male green frogs use this technique against other male frogs in addition to other intruders that might have interest in nearing their territory. Territoriality also plays a role in mating, as females favor males who are strong in this field and exhibit strong mating calls. Predators that attack green frog eggs include bugs such as beetles, water bugs, and water scorpions. Several different types of birds typically pose a threat to adult frogs.

DESCRIPTION

• This species is a mid-sized true frog. Adult green frogs range from 5–10 cm (2.0–3.9 in) in body length (snout to vent, excluding the hind legs). The typical body weight of this species is from 28 to 85 g.

• The sexes are sexually dimorphic in a few ways: mature females are typically larger than males, the male tympanum is twice the diameter of the eye, whereas in females, the tympanum diameter is about the same as that of the eye, and males have bright yellow throats.

• The dorsolateral ridges, prominent, seam-like skin folds that run down the sides of the back, distinguish the green frog from the bullfrog, which entirely lacks them.

• Green frogs usually have green heads, while the body is brown, gray, or dark green. The green head can be more or less prominent on certain individuals, with some frogs only having green on the side of their heads while other frogs are green all the way down their backs.

• The belly is white with black mottling.

•  Male green frogs in breeding condition have yellow throats. Green frogs are darker colored on colder days to help absorb heat. Green frogs can sometimes be blue due to a genetic mutation known as axanthism that prevents the frog from producing yellow pigments (yellow and blue pigments together make the color green).

• Green frog tadpoles are olive green and iridescent creamy-white below. Metamorphosis can occur within the same breeding season, or tadpoles may overwinter to metamorphose the next summer.

REPRODUCTION

Breeding Behavior:

• Males typically achieve sexual maturity within one year, while females may take two to three years.

• During the breeding season, which spans from spring through summer, males establish and maintain breeding territories. The extent of this season can vary based on location and temperature, with a strong positive correlation between temperature and breeding activity.

• During this critical period, females lay egg clutches containing 1000 to 7000 eggs. These clutches are carefully positioned in surface films, typically measuring 15–30 cm in diameter, and attached to aquatic vegetation in shallow waters to safeguard them from predators.

• Some females may even lay two clutches in a single season, with their size reaching a maximum of 98–105 mm.

• When females are ready to mate, they enter male territories and assume a submissive posture, signifying their readiness. The selection of a mate is a deliberate process that can take 2 to 3 days.

• Females tend to favor males displaying territorial behavior and strong mating calls, driven by their desire for optimal reproductive success and the transmission of favorable traits to their offspring.

• Once a female approaches a male and initiates physical contact, mating occurs. The males clasp the females, and fertilization takes place.

• Importantly, the majority of the eggs are deposited within the resident male's territory, rather than a satellite male's, indicating that polyandry is not a common practice in this species. This behavior serves to enhance offspring protection.

Tadpole Development:

• Research has shown that wild green frogs, whether inhabiting contaminated suburban backyard ponds or relatively pristine forested ponds, can undergo sex reversal. This phenomenon appears to be a natural occurrence, but it remains uncertain whether these naturally sex-reversed green frogs are capable of reproduction.

• After the eggs are laid within the resident male's territory, the process of development commences. The typical larval stage for green frogs spans between 70 and 360 days, contingent on the timing of egg deposition. Notably, the period of most significant growth in adult frogs occurs primarily from mid-May to mid-September. This period closely aligns with the mean monthly temperature and the duration of favorable conditions for feeding.

• Sexual maturity is attained approximately one year after metamorphosis, but frogs do not become sexually active until the year following maturity. Importantly, there is no sexual size dimorphism observed in fully mature frogs.

HABITAT

Green frogs are associated with bodies of water and have been found in a variety of habitats, living at the margins of shallow freshwater ponds, roadside ditches, lakes, swamps, and streams, as well as vernal pools and other temporary bodies of water, though less so than other frogs.