Vomerine teeth present. Tongue more or less free posteriorly. Pupil of the eye horizontal. Toes webbed. Tips of fingers and toes expanded into discs. Tympanic membrane smaller than eye. When the hind leg is stretched along the body, the tibio-tarsal articulation commonly reaches the anterior edge of the eye. Dorsal skin smooth, ventral skin granular. Dorsal coloration varies from green to light-grey, brown, or almost black depending on substrate color and temperature. Coloration changes depending on substrate. No dark spot below the eye. Ventral surface white or yellowish. Dorsal surface divided from ventral surface by thin, dark, uninterrupted band with outer white edging. This band usually forms an inguinal loop, except for some individuals of H. arborea schelkownikowi. If the inguinal loop is absent, the dark band reaches the inner surface of the groin. A light line bordering lips. Male differs from female by having a large guttural vocal sac (visible externally) which is distinguished by darker skin folds and wrinkles on the throat.
Protection of habitats seems to be the most important method of conservation of H. arborea.
Distribution and Habitat
The subspecies H. arborea arborea inhabits almost all of Europe. The northern margin of the range runs approximately from Denmark (Aarhus and Jutland), Sweden (Scania) and the southern shore of the Baltic Sea in Lithuania (Vilnius City: 54º41'N, 25º17'E) through Byelorussia (approximately on the line: towns of Oshmyany - Uzda - Slutsk) to southern Russia. From there, the margin runs south- and south-eastwards approximately along the line Bryansk Province - Kursk Province - west of Byelgorod Province (Shebekino District), then southwards in Ukraine from Kharkov City to Dnepropetrovsk Province to Donetsk Province. In Crimea, the frog is known from the southern shore and the extreme northwest of the peninsula. The frog is absent from eastern and southern parts of the Iberian Peninsula and Southern France. H. arborea schelkownikowi lives in the Caucasus. Its northern range runs in Russia approximately from Krasnodar Region along the line Abrau Peninsula in Novorossiik District - Goryachii Klyuch Town - Maikop Town - Stavropol Region (Stavropol City: 45º03'N, 41º59'E). From there, the margin runs in Stavropol Region to the south-east and then to the east: North Ossetia to Chechnya to Daghestan. The subspecies is absent in the highlands of the Great Caucasus. The eastern part of the southern margin of the range runs from the Northern Turkey to Georgia and Azerbaijan. The southern margin of the range is insufficiently known. H. arborea kretensis lives in Crete, Rhodos, Aegean, Peloponnese and the west of Asia Minor; H. arborea molleri in Northwestern Spain and Portugal; H. arborea sarda in Corsica, Sardinia and Elba.
The Common Tree Frog inhabits well-illuminated, broad-leafed and mixed forests, bushlands, gardens, vineyards, orchards, parks, lake shores and stream banks. Dark and dense forests are avoided. Meadows are primarily used for reproduction. In the southern areas of the European part of the range, i.e. in the forest steppe zone, the tree frog inhabits insular forests and dense vegetation of floodplains. In mountains, it lives only in forests and in more or less wet transformed landscapes, and sometimes penetrates the subalpine belt. Spawning occurs in stagnant waters such as lakes, ponds, swamps and reservoirs, sometimes even in ditches and puddles.
Habitat and Ecology
Life History and Behavior
Lifespan, longevity, and ageing
Molecular Biology and Genetics
Barcode data: Hyla arborea
No available public DNA sequences.
Download FASTA File
Statistics of barcoding coverage: Hyla arborea
Public Records: 17
Specimens with Barcodes: 17
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
- 2006Least Concern(IUCN 2006)
- 2006Least Concern
- 2004Near Threatened
Life History, Abundance, Activity, and Special Behaviors
In suitable habitats in the southern part of the range this is a common amphibian. For example, in the south of the former Soviet Union up to 20 specimens per 100 m of pond shore may be counted in spring. After reproduction, the population density is maximum in river valleys covered with broad-leafed trees.During the day, H. arborea usually sit on the stems and broad leaves of trees, bushes and large herbaceous vegetation. The frog is active primarily in the evening and at night, when it comes down to the ground from vegetation to forage and to rehydrate. During the autumn migration to hibernacula, H. arborea are active during the day. Hibernation occurs on land from September - December to February - early May, on land (in soil, burrows, heaps of stones and holes in trees). Reproduction occurs from April - May, but sometimes in March, June or even late July. As a rule, more males are found in breeding pools than females. Females enter pools after males and leave immediately after breeding. Clutch contains about 200-2000 eggs deposited in portions, usually having the form of small rounded clumps containing from 3 to 100 eggs. Metamorphosis occurs from June to September, depending on the geographic position of a locality. In some cases, the larvae overwinter and complete transformation the following summer. Young froglets in the first time remain on the shore climbing grass and small bushes. Hyla arborea prey mainly on insects. Its ability for long leaps makes it possible to forage on fast flying insects, which comprise a considerable proportion of its food. The frogs forage on land. During the breeding season, adults forage periodically on the shore and on high plant stems above the water surface.
Life History, Abundance, Activity, and Special Behaviors
The tree frog displays a considerable decline and extinction in the West and Central Europe. It is caused by loss of breeding habitats, habitat isolation and fragmentation, pollution and collecting by people, as well as climate changes. However, in many large areas of its southern part of the range, e.g. in Ukraine and the Caucasus, the species is not rare and does not display population declines.
In Sweden, a "restocking program" has successfully has increased the population from 2,000 (1980) to 50,000 (2008) in about 900 breeding ponds and the species has been repopulated to its historic range. The species benefits from pond creation programs in several areas of Central Europe. This is often a flagship species for numerous restoration programs.
Relevance to Humans and Ecosystems
Relation to Humans
Although some kinds of human activity lead to decline and extinction of populations of H. arborea (see above), construction of a system of fish ponds, ditches, channels etc. sometimes cause local increase in the number of this species.
European tree frog
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The European tree frog (Hyla arborea formerly Rana arborea) is a small tree frog found in Europe, Asia and part of Africa. Based on molecular genetic and other data, a number of taxa formerly treated as subspecies of H. arborea are now generally recognized as full species  
European tree frogs are small; males range from 32–43 mm (1.3–1.7 in) in length, and females range from 40–50 mm (1.6–2.0 in) in length. They are slender, with long legs. Their dorsal skin is smooth, while their ventral skin is granular. Their dorsal skin can be green, gray, or tan depending on the temperature, humidity, or their mood. Their ventral skin is a whitish color, and the dorsal and ventral skin is separated by a dark brown lateral stripe from the eyes to the groin. Females have white throats, while males have golden brown throats with large (folded) vocal sacs. The head of H. arborea is rounded, the lip drops strongly, the pupil has the shape of a horizontal ellipse, and the tympanum is clearly recognizable. Also, the discs on the frog's toes, which it uses to climb trees and hedges, is a characteristic feature of H. arborea . Also, like other frogs, their hind legs are much larger and stronger than the fore legs, enabling the frogs to jump rapidly.
Distribution and habitat
Members of the H. arborea species complex are the only representatives of the widespread tree frog family (Hylidae) indigenous to mainland Europe. and are found across most of Europe (except Britain and Ireland), northwest Africa, and temperate Asia to Japan. This species complex is native to these countries:
Albania; Armenia; Austria; Azerbaijan; Belarus; Belgium; Bosnia and Herzegovina; Bulgaria; Croatia; the Czech Republic; Denmark; France; Georgia; Germany; Greece; Hungary; Israel (found in the Ayalon Valley); Italy; Liechtenstein; Lithuania; Luxembourg; Macedonia, the Republic of; Moldova; Montenegro; the Netherlands; Poland; Portugal; Romania; the Russian Federation; Serbia; Slovakia; Slovenia; Sweden; Switzerland; Turkey; Ukraine.
European tree frogs can be found in marshlands, damp meadows, reed beds, parks, gardens, vineyards, orchards, stream banks, lakeshores, or humid or dry forests. They tend to avoid dark or thick forests, and they are able to tolerate some periods of dryness; therefore, sometimes they are found in dry habitats.
- Historically, tree frogs were used as barometers because they respond to approaching rain by croaking.
- Depending on subspecies, temperature, humidity, and the frog's 'mood', skin colour ranges from bright to olive green, grey, brown and yellow.
- European tree frogs eat a variety of small arthropods, such as spiders, flies, beetles, butterflies, and smooth caterpillars. Their ability to take long leaps allow them to catch fast-flying insects, which make up most of their diets.
- They hibernate in walls, cellars, under rocks, under clumps of vegetation, or buried in leaf piles or manure piles.
European tree frogs reproduce in stagnant bodies of water, such as lakes, ponds, swamps, reservoirs, and sometimes puddles, from late March to June. They croak in the breeding season, even when migrating to their mating pools or ponds. Males will often change breeding ponds, even within the same breeding season. After a spring rain, the males will call females from low vegetation or shallow ponds. About 800 to 1000 eggs are laid in clumps the size of a walnut. Individual eggs are about 1.5 mm in diameter. After 10–14 days, the eggs hatch. Then, after three months, tadpoles metamorphose into frogs. Metamorphosis usually peaks from late July to early August. They are able to live for up to 15 years.
According to the IUCN Red List of Endangered Species, H. arborea is “listed as Least Concern in view of its wide distribution, presumed large population, and because it is unlikely to be declining fast enough to qualify for listing in a more threatened category.” However, according to the IUCN, the population trend of H. arborea is decreasing. Some of the main threats to European tree frogs include habitat fragmentation and destruction, pollution of wetlands, predation from fish, capture for the pet trade, and climate change. Besides these main threats, other possible reasons for the decline in their populations include increased UVB radiation and local and far-ranging pesticides, fertilizers, and pollutants. Trout have been observed preying on European tree frogs, and in Europe, trout introduced into a pond result in a significant decline in their population. While H. arborea is sensitive to habitat fragmentation, habitat restoration (beginning in the 1980s) has been successful to increase populations. Besides habitat restoration, other attempts to increase population have included building of new breeding ponds, creation of “habitat corridors to connect breeding sites”, and reintroductions. This has been successful in Sweden, Latvia, and Denmark. Habitat protection has been shown to be the most important approach to conserving European tree frog populations.
Hyla arborea var. molleri Bedriaga, 1890
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