The common frog, like all amphibians, begins its life in the water. It hatches from an egg as a fish like tadpole before growing legs and lungs as an adaptation for its adult life on land. As a tadpole, the common frog has gills like a fish. As it matures, it grows lungs that work when the frog puffs its throat in and out. The adult frog can also breathe through its moist skin, which allows it to hibernate underwater.

Habits: The common frog lives in grassy meadows and woods, on moors and marshes, along canals and rivers, and beside lakes and ponds. During summer the common frog is most active at night. It spends the day in damp, hidden places, such as under a log or in reeds at the edge of a pond. Sometimes it emerges during the day to bask in the sun. The frog hibernates from November to March either on land in a secluded spot, or underwater, hidden in the soft mud.

Food and Feeding: The adult frog eats snails, beetles, spiders, wood lice, centipedes, and worms. In fall the frog eats more to prepare for hibernation. The frog sits motionless, waiting to ambush insects with its sticky, whip like tongue. Once it catches its prey, the frog blinks its large eyes, causing them to push down into its mouth, thus forcing the food down its throat. Tadpoles eat algae until they are large enough to catch insects.

Predators: Hedgehogs, stoats, badgers, otters, grass snakes, and owls all prey on the common frog. The frogs thin skin and lack of defenses make it easy prey. Tadpoles are eaten by fish, ducks, newts, and various types of aquatic insect. Man is a predator of the common frog: large numbers are caught every year for use in school and research laboratories. In France and Belgium the frog is eaten in early spring, when the large edible adults are hibernating.

Breeding: The frog spends most of the year away from water, returning in spring to breed. Male frogs gather at the waters edge, where they croak continuously to attract females. Once a male finds a female, he seizes her, jumps on her back, and clasps her firmly. The two frogs remain locked in this position until the eggs have been laid and the male has fertilized them. Adult frogs remain in or near the water for one to two months after mating. The male has special pads to help him grip the female.

Nature watch: Common frogs can be seen in the spring when they return to the water to lay eggs. Males make noisy croaking sounds that make the frogs easy to find. After hatching, thousands of tadpoles can be seen swimming along the edge of the water. Throughout the summer and fall common frogs can be seen in most parts of their habitats on dry land. Common frogs are now more common in backyard ponds than they are in the countryside. Even a small pond can support a thriving colony.

Key Facts:
Sizes:
Length: Males, 3 in. Females, 4 in. Immature frogs up to 1 ½ in.

Breeding:
Sexual maturity: 2-3 years
Mating: Early spring
No. of eggs: 2,000-4,000
Metamorphosis: 12-14 weeks from tadpole to immature frog

Lifestyle:
Habit: Solitary; sociable during breeding season
Diet: Small insects, including flies, beetles, crickets, slugs, snails, centipedes, and worms
Life span: Up to 12 years in captivity

Related Species: Close relatives include the edible frog Rana esculenta, the North American bullfrog R. catesbeiana, and the leopard frog R. pipiens.
Distribution: Range extends across northern Europe and east into the Soviet Union and Asia.
Conservation: Frogs were common earlier this century, but numbers have declined drastically because of habitat loss and use in laboratories. Pollution from pesticides and fertilizers also takes its toll.

Life cycle of the Common Frog: The female lays 2,000 to 4,000 eggs, called spawn. They are protected by a layer of jelly and clustered together. The speed of the eggs’ development depends on water temperature, but within a few days the tadpoles begin to grow. Their black bodies become clearly visible through the jelly. Ten days later the tadpoles have eaten all the jelly and emerge to feed on algae. During the next 12 to 14 weeks, they develop legs and slowly lose their tails. Their gills are replaced by lungs so that they can breathe air when they leave the water in June. Adults return to breed two or three years later.

Did You Know:
Some frogs have a disease called neotony: they never develop into adults and remain tadpoles their entire lives.
The frog changes its skin color to camouflage itself among vegetation.
During breeding season, males may attempt to mate with any moving object, thinking that it is a female.
The adult frog cannot feed underwater like the tadpole.