European Tree Frog
The European tree frog (Hyla arborea) is a small frog that can grow to a maximum length of 4.5 cm.
They are the only members of the widespread tree frog family (Hylidae) indigenous to Mainland Europe. Characteristic are the discs on the frog's toes which it uses to climb trees and hedges.
The European tree frogs actually don't live in forests, but rather prefer sunny forest edges, bushy heaths, wet dune pans, wet scrubland and extensively used meadows and parks with ponds rich in submerged vegetation without fish nearby. These habitats are increasingly influenced by human activity. Hyla arborea, the common tree frog, is endangered in western Europe (nearly extinct in Belgium) while the more common Mediterranean tree frog lives in wet gardens, vineyards, camping areas, and near pine trees.
Photo: Adrian Gheorghe 2nd May 2010
Location: Slaveni Castrum area
The Grass Frog
The excellent and informative text below is from:
Ramos, M. 2001. "Rana temporaria" (On-line), Animal Diversity Web. Accessed May 13, 2005 at
(European frog)Kingdom: Animalia
Species: Rana temporaria
Geographic RangeRana temporaria is a common terrestrial frog in Great Britain, Europe and northwestern Asia. In continental Europe they are referred to as "grass frog" or "brown frog". They are resistant to cold climates and live as far north as the Arctic circle in Scandinavia, farther north than any other amphibian in the region.
HabitatRana temporaria can be found in just about any damp habitat within its range, though they are more common in cooler upland forests and wet meadows. They are the most common frog in mountain lakes.
Terrestrial Biomes: taiga; forest; mountains.
Aquatic Biomes: lakes and ponds; rivers and streams.
Physical DescriptionMass 22.70 g (average)
Rana temporaria is a small animal that has a squat body and no tail. They have a wide, flat head connected to a short, solid body. The lower segments of the frogs backbone are fused, forming a stiff rod called the urostyle. Their urostyle and their pelvic bones help provide firmness and strength to the rear of the body, which is where the muscles used for jumping attach to the skeleton. Their powerful legs are not only used for jumping but for swimming as well.
They have a brown-black triangular area around their eardrum, and brown shades covering the rest of their body, though there is a lot of variation in color, with gray, olive, even yellow or pink hues as well. Females are typically yellower and may have patches of red on their sides. Males develop blue patches on their back and throat during breeding season. For the most part females tend to be larger than males. The common frog is approximately 7.5-8 cm long. They lack vocal sacs and therefore can only be heard approximately 50 meters away. (Mattison 1982; Britannica 1999-2001 )
ReproductionMating is by means of external fertilization and takes place in water. The male climbs on the back of the female and grasps her body with his forelegs. He releases his sperm as she lays her eggs. Once the male mounts a female he will not release her until egg-laying is complete. The eggs are in gelatinous envelopes (about 400 eggs) and are laid in thick groupings. It takes approximately 30-40 days for their eggs to hatch. A relatively cold spring initiates mating behavior and maturation of eggs. During metamorphosis the tadpole grows legs-the hind legs are the first to grow. Its tail is absorbed into its body and it loses its gills and grows lungs. The structure of the digestive system, heart and skeleton change as well.
Rana temporaria breeds in warmer lowlands in February & March and in the north and at high altitudes as late as June. The breeding period is much shorter in this species than in others; in 3 nights these frogs will lay hundreds of eggs.
BehaviourThese frogs communicate through croaks. Air from the lungs is forced over vocal cords in the throat. Communication is very important during mating season, for this is how males attract females. After mating, the frogs abandon their eggs. They do not take care of them.
They tend to hide in damp places during the day, but often wander far from standing water. They search for food during the night or on rainy days. During the winter they stay in the soil of earth holes. They are capable of recognizing the qualities of their own homeland. In three years they reach sexual maturity, returning to the water where they originally metamorphosed to spawn. ( Duellman and Trueb 1986 )
Food HabitsRana temporaria eats insects, their larvae, wood lice, spiders, snails and worms. They are able to detect worms by smell. Eating habits are greatly influenced by the time of year.
(Duellman and Trueb 1986; Mattison 1993 )
Economic Importance for HumansRana temporaria are of great importance to humans. They consume insects, which helps control populations of mosquitoes and crop-damaging insects. Frogs are also important when it comes to teaching and scientific research. Adult frogs are used to teach students about the anatomy and physiology of vertebrates and help scientist learn about embryonic development. Ecologists monitor frog populations as they reflect the health of the ecosystem as a whole. In addition, frog legs are a delicacy in many parts of Europe. (Mattison 1987)
Conservation StatusThis common species is currently in no danger of extinction, but local populations can be very unstable. Disturbance of breeding ponds, unusually hard freezes, and pollution by herbicides are all known to wipe out the species in a region.
ContributorsMaribel Ramos (author), University of Michigan: October, 2001. Phil Myers (editor), Museum of Zoology, University of Michigan: October, 2001.
ReferencesBaynes, T., S. William Robertson. 1999-2001. "Britannica Encyclopaedia" (On-line). Accessed "March 1, 2001" at http://britannica.com/ .
Duellman, W., L. Trueb. 1986. Biology of Amphibians . US: Mc Graw-Hill, Inc.
Griffiths, R., J. Foster. 1998. The Effect of Social Interactions on Tadpole Activity and Growth in the British Anuran Amphibians. Journal of Zoology , 135: 431-437.
Mattison, C. 1982. The Care of Reptiles and Amphibians in Captivity . UK: Blandford Press.
Mattison, C. 1987. Frogs and Toads of the World . New York, New York: Facts on File, Inc.
Mattison, C. 1993. Keeping and Breeding Amphibians . UK: Blandford Press.
Text above: Ramos, M. 2001. "Rana temporaria" (On-line), Animal Diversity Web. Accessed May 13, 2005 at
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