The European tree frog (''Hyla arborea'') is a small tree

frog A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura (ανοὐρά, literally ''without tail'' in Ancient Greek). The oldest fossil "proto-frog" ''Triadobatrachus'' is ...

. As traditionally defined, it was found throughout much of Europe, Asia and northern Africa,Frost, Darrel R. ''Amphibian Species of the World''. Allen Press, Inc., 1985, p. 126. but based on molecular genetic and other data several populations formerly included in it are now recognized as separate species (for example, '' H. intermedia'' of Italy and nearby, '' H. molleri'' of the Iberian Peninsula, '' H. meridionalis'' of parts of southwestern Europe and northern Africa, and '' H. orientalis'' of parts of Eastern Europe, Turkey and the Black Sea and Caspian Sea regions), limiting the true European tree frog to Europe from France to Poland and Greece.Duellman, William E. (2003). ''Grzimek's Animal Encyclopedia''. 2nd Ed., Vol. 2. Gale, p. 235.Stöck M., Dufresnes C., Litvinchuk S.N., Lymberakis P., Biollay S., Berroneau M., Borzée A., Ghali K., Ogielska M., and Perrin N. (2012). Cryptic diversity among Western Palearctic tree frogs: Postglacial range expansion, range limits, and secondary contacts of three European tree frog lineages (Hyla arborea group). ''Molecular Phylogenetics and Evolution'' 65: 1-9.

Description

European tree frogs are small; males range from in length, and females range from in length. They are slender, with long legs. Their

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal c ...

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 Lateral is a geometric term of location which may refer to: Healthcare *Lateral (anatomy), an anatomical direction * Lateral cricoarytenoid muscle * Lateral release (surgery), a surgical procedure on the side of a kneecap Phonetics *Lateral co ...

stripe from the eyes to the groin. Females have white throats, while males have golden brown throatsHaltenorth, T. (1979). ''British and European Mammals, Amphibians, and Reptiles’’. Irwin & Co. Ltd., p. 126. with large (folded)

vocal sac The vocal sac is the flexible membrane of skin possessed by most male frogs and toads. The purpose of the vocal sac is usually as an amplification of their mating or advertisement call. The presence or development of the vocal sac is one way ...

s. The head of ''H. arborea'' is rounded, the lip drops strongly, the

pupil The pupil is a black hole located in the center of the Iris (anatomy), iris of the Human eye, eye that allows light to strike the retina.Cassin, B. and Solomon, S. (1990) ''Dictionary of Eye Terminology''. Gainesville, Florida: Triad Publishing ...

has the shape of a horizontal ellipse, and the tympanum is clearly recognizable. The discs on the frog's toes, which it uses to climb trees and hedges, is a characteristic feature of ''H. arborea'' . Like other frogs, their hind legs are much larger and stronger than the fore legs, enabling the frogs to jump rapidly.Stöck M., Dubey S., Klütsch C., Litvinchuk S.N., Scheidt U., and Perrin N. (2008). Mitochondrial and nuclear phylogeny of circum-Mediterranean tree frogs from the Hyla arborea group. ''Molecular Phylogenetics and Evolution'' 49: 1019-1024.

Distribution and habitat

Members of the ''H. arborea''

species complex In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

are the only representatives of the widespread

tree frog A tree frog (or treefrog) is any species of frog that spends a major portion of its lifespan in trees, known as an arboreal state. Several lineages of frogs among the Neobatrachia have given rise to treefrogs, although they are not closely rela ...

family (Hylidae)

indigenous Indigenous may refer to: *Indigenous peoples *Indigenous (ecology), presence in a region as the result of only natural processes, with no human intervention *Indigenous (band), an American blues-rock band *Indigenous (horse), a Hong Kong racehorse ...

mainland Europe Continental Europe or mainland Europe is the contiguous continent of Europe, excluding its surrounding islands. It can also be referred to ambiguously as the European continent, – which can conversely mean the whole of Europe – and, by ...

. and are found across most of Europe (except 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; Cyprus; 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."''Hyla arborea''"
Amphibiaweb.org
2010. Retrieved 2 December 2010. It has also been introduced to the United Kingdom, (although at least one British population, now thought to be extinct, may have been nativeNaish, Darren
''Britain’s lost tree frogs: sigh, not another ‘neglected native’''
2007. Retrieved 20 December 2017.), and it has been reintroduced to Latvia. 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

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

Behavior

*Historically, tree frogs were used as

barometer A barometer is a scientific instrument that is used to measure air pressure in a certain environment. Pressure tendency can forecast short term changes in the weather. Many measurements of air pressure are used within surface weather analysis ...

s 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

arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chiti ...

s, 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 Hibernation is a state of minimal activity and metabolic depression undergone by some animal species. Hibernation is a seasonal heterothermy characterized by low body-temperature, slow breathing and heart-rate, and low metabolic rate. It most ...

in walls, cellars, under rocks, under clumps of vegetation, or buried in leaf piles or manure piles.Wells, K. D. ‘‘The Ecology of Behavior of Amphibians.’’ The University of Chicago, 2007.

Reproduction

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.Lardner, B. (2000). Morphological and life history responses to predators in larvae of seven anurans. ''Oikos'', 88(1): 169–180. 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,

tadpole A tadpole is the larval stage in the biological life cycle of an amphibian. Most tadpoles are fully aquatic, though some species of amphibians have tadpoles that are terrestrial. Tadpoles have some fish-like features that may not be found ...

s metamorphose into frogs. Metamorphosis usually peaks from late July to early August. They are able to live for up to 15 years.

Conservation status

According to the

IUCN Red List of Endangered Species The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biologi ...

, ''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 Population growth is the increase in the number of people in a population or dispersed group. Actual global human population growth amounts to around 83 million annually, or 1.1% per year. The global population has grown from 1 billion in 1800 to ...

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 In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...

. Besides these main threats, other possible reasons for the decline in their populations include increased

UVB radiation Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...

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 Restoration ecology is the scientific study supporting the practice of ecological restoration, which is the practice of renewing and restoring degraded, damaged, or destroyed ecosystems and habitats in the environment by active human interrupt ...

(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.

Gallery

File:P7101931.JPG File:Hyla_arborea_(Marek_Szczepanek).jpg File:Tree frog in Romania.JPG File:Hyla arborea01.jpg File:Laubfrosch-wiki.jpg File:Romanian European Tree Frog.JPG File:Hyla arborea var. molleri (Hello folks).jpg, Formerly included in the European tree frog, the form ''molleri'' is now recognized as its own species, the Iberian tree frog File:HylaArboreaTadpole+Metam.jpg, ''Hyla arborea''

and metamorph File:Boomkikkers bij Witteveen - SoundCloud - luc de bruijn.ogg, European tree frogs in

References

{{Taxonbar, from=Q2142057 Hyla Amphibians of Europe Least concern biota of Europe Articles containing video clips Amphibians described in 1758 Taxa named by Carl Linnaeus gl:Estroza