Common Frog
Encyclopedia
The Common Frog, Rana temporaria also known as the European Common Frog or European Common Brown Frog is found throughout much of Europe
as far north as well north of the Arctic Circle
in Scandinavia and as far east as the Urals, except for most of Iberia
, southern Italy
, and the southern Balkans
. The farthest west it can be found is Ireland
, where it has long been thought erroneously to be an entirely introduced species.
, and male Common Frogs have been known to turn greyish blue in the mating season (video on page). Additionally, albino Common Frogs have been found with yellow skin and red eyes. Their average weight is 22.7g (0.8oz). Females are usually slightly larger than males.
Common Frogs' flanks, limbs and backs are covered with irregular dark blotches and they usually sport a chevron-shaped spot on the back of their neck. Unlike other amphibians, Common Frogs generally lack a middorsal band, and when they have one, it is comparatively faint. In many countries the moor frog
s do have a light dorsal band which easily distinguishes them from common frogs.
The frogs' underbellies are white or yellow (occasionally more orange in females) and can be speckled with brown or orange.
Common Frogs have relatively short hind legs and possess webbed feet. The legs of the agile frog
are much longer which distinguishes them from common frogs along with the agile frog's fainter colouration. Their eyes are brown with transparent horizontal pupils, and they have transparent inner eyelids to protect their eyes while underwater, as well as a 'mask' which covers their eyes and eardrums.
Males are distinguishable from females due to hard swellings (called nuptial pad
s) on their first finger. These are used for gripping females during mating. Also, during the mating season, males' throats often turn white. A final differentiation can be the colour- during the mating season, males are generally light and greyish in colour, whereas the female is browner, or even red.
The mating season is short, just a week in March after which the frogs move back to their terrestrial habitat.
as far north as northern Scandinavia inside the Arctic Circle
and as far east as the Urals, except for most of Iberia
, southern Italy
, and the southern Balkans
. Other areas which the Common Frog has been introduced to include the Isle of Lewis, Shetland, Orkney and the Faroe Islands
.
of a suitable size, although they do not feed at all during the breeding season. Favourite foods include insect
s (especially flies
), snail
s, slug
s and worm
s. The frogs catch their prey on their long, sticky tongues. Their feeding habits change significantly throughout their lives; whereas older frogs will feed only on land, younger frogs will also feed in the water. Tadpoles are mostly herbivore
s, feeding on algae, detritus and some plants, although they will also eat other animals in small amounts.
, they emerge as late as early June. Common frogs hibernate in running waters, muddy burrows, or in layers of decaying leaves and mud at the bottom of ponds. The oxygen uptake through the skin suffices to sustain the needs of the cold and motionless frogs during hibernation.
which float in large clusters.
and the parasitic fungus Batrachochytrium dendrobatidis
which has been implicated in extinctions of amphibian species around the world. Loss of habitat and the effect of these diseases has caused the decline of populations across Europe in recent years. It is thought that the spread of the Chytridiomycota
fungus has been facilitated by the effects of global warming. The common frog is listed as a species of Least Concern
on the IUCN Redlist of Threatened Species.
s, gull
s, duck
s, tern
s, heron
s, pine marten
s, stoat
s, weasel
s, polecats
, badger
s and otter
s.
Some frogs are killed, but rarely eaten, by domestic cats, and large numbers are killed on the roads by motor vehicles.
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
as far north as well north of the Arctic Circle
Arctic Circle
The Arctic Circle is one of the five major circles of latitude that mark maps of the Earth. For Epoch 2011, it is the parallel of latitude that runs north of the Equator....
in Scandinavia and as far east as the Urals, except for most of Iberia
Iberian Peninsula
The Iberian Peninsula , sometimes called Iberia, is located in the extreme southwest of Europe and includes the modern-day sovereign states of Spain, Portugal and Andorra, as well as the British Overseas Territory of Gibraltar...
, southern Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
, and the southern Balkans
Balkans
The Balkans is a geopolitical and cultural region of southeastern Europe...
. The farthest west it can be found is Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...
, where it has long been thought erroneously to be an entirely introduced species.
Appearance
Adult Common Frogs have a body length of 6 to 9 centimetres (2.5 to 3.7in) and their backs and flanks vary in colour, with olive green grey-brown, brown, olive-brown, grey, yellowish or rufous possible. However, Common Frogs are known to be able to lighten and darken their skin in order to match their surroundings. It is also not unknown for more unusual colouration- both black and red individuals have been found in ScotlandScotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
, and male Common Frogs have been known to turn greyish blue in the mating season (video on page). Additionally, albino Common Frogs have been found with yellow skin and red eyes. Their average weight is 22.7g (0.8oz). Females are usually slightly larger than males.
Common Frogs' flanks, limbs and backs are covered with irregular dark blotches and they usually sport a chevron-shaped spot on the back of their neck. Unlike other amphibians, Common Frogs generally lack a middorsal band, and when they have one, it is comparatively faint. In many countries the moor frog
Moor Frog
The Moor Frog is a slim, reddish-brown, semi-aquatic amphibian native to Europe and Asia. It is a member of the family Ranidae, or "true frogs".-Taxonomy:...
s do have a light dorsal band which easily distinguishes them from common frogs.
The frogs' underbellies are white or yellow (occasionally more orange in females) and can be speckled with brown or orange.
Common Frogs have relatively short hind legs and possess webbed feet. The legs of the agile frog
Agile Frog
The Agile Frog is a frog in the genus Rana in the family of the true frogs.-Physical description:This species are skinny and have long limbs and a pointy snout. Adult males are rarely larger than 6.5 centimeters, while females can get up to 8 centimeters. Its ventral surface is light brown,...
are much longer which distinguishes them from common frogs along with the agile frog's fainter colouration. Their eyes are brown with transparent horizontal pupils, and they have transparent inner eyelids to protect their eyes while underwater, as well as a 'mask' which covers their eyes and eardrums.
Males are distinguishable from females due to hard swellings (called nuptial pad
Nuptial pad
A nuptial pad is a secondary sex characteristic present on some mature male frogs and salamanders. Triggered by androgen hormones, this breeding gland appears as a spiked epithelial swelling on the forearm and prepollex that aids with grip, used primarily by males to grasp females during amplexus...
s) on their first finger. These are used for gripping females during mating. Also, during the mating season, males' throats often turn white. A final differentiation can be the colour- during the mating season, males are generally light and greyish in colour, whereas the female is browner, or even red.
The mating season is short, just a week in March after which the frogs move back to their terrestrial habitat.
Distribution
The Common Frog is found throughout much of EuropeEurope
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
as far north as northern Scandinavia inside the Arctic Circle
Arctic Circle
The Arctic Circle is one of the five major circles of latitude that mark maps of the Earth. For Epoch 2011, it is the parallel of latitude that runs north of the Equator....
and as far east as the Urals, except for most of Iberia
Iberian Peninsula
The Iberian Peninsula , sometimes called Iberia, is located in the extreme southwest of Europe and includes the modern-day sovereign states of Spain, Portugal and Andorra, as well as the British Overseas Territory of Gibraltar...
, southern Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
, and the southern Balkans
Balkans
The Balkans is a geopolitical and cultural region of southeastern Europe...
. Other areas which the Common Frog has been introduced to include the Isle of Lewis, Shetland, Orkney and the Faroe Islands
Faroe Islands
The Faroe Islands are an island group situated between the Norwegian Sea and the North Atlantic Ocean, approximately halfway between Scotland and Iceland. The Faroe Islands are a self-governing territory within the Kingdom of Denmark, along with Denmark proper and Greenland...
.
Ireland
The Common Frog has long been thought to be an entirely introduced species in Ireland, however, genetic analyses suggest that particular populations in the south west of Ireland are indeed indigenous to the country. The authors propose that the Irish frog population is a mixed group that includes native frogs that survived the last glacial period in ice free refugia, natural post-glacial colonisers and recent artificial introductions from Western Europe.Diet
Adult Common Frogs will feed on any invertebrateInvertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
of a suitable size, although they do not feed at all during the breeding season. Favourite foods include insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s (especially flies
Fly
True flies are insects of the order Diptera . They possess a pair of wings on the mesothorax and a pair of halteres, derived from the hind wings, on the metathorax...
), snail
Snail
Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...
s, slug
Slug
Slug is a common name that is normally applied to any gastropod mollusc that lacks a shell, has a very reduced shell, or has a small internal shell...
s and worm
Worm
The term worm refers to an obsolete taxon used by Carolus Linnaeus and Jean-Baptiste Lamarck for all non-arthropod invertebrate animals, and stems from the Old English word wyrm. Currently it is used to describe many different distantly-related animals that typically have a long cylindrical...
s. The frogs catch their prey on their long, sticky tongues. Their feeding habits change significantly throughout their lives; whereas older frogs will feed only on land, younger frogs will also feed in the water. Tadpoles are mostly herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
s, feeding on algae, detritus and some plants, although they will also eat other animals in small amounts.
Habitat and habits
Outside the breeding season, common frogs live a solitary life in damp places near ponds or marshes or in long grass. They are normally active for much of the year, only hibernating in the coldest months, sometime between August and early June depending on latitude and altitude. In the most northern extremities of their range they may be trapped under ice for up to nine months of the year, but recent studies have shown that in these conditions they may be relatively active at temperatures close to freezing. In the British Isles, common frogs typically hibernate from late October to January. They will re-emerge as early as February if conditions are favourable, and migrate to bodies of water such as garden ponds to spawn. Where conditions are harsher, such as in the AlpsAlps
The Alps is one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east through Italy, Switzerland, Liechtenstein and Germany to France in the west....
, they emerge as late as early June. Common frogs hibernate in running waters, muddy burrows, or in layers of decaying leaves and mud at the bottom of ponds. The oxygen uptake through the skin suffices to sustain the needs of the cold and motionless frogs during hibernation.
Breeding
Common frogs breed in shallow, still, fresh water such as ponds, with breeding commencing in March. The adults congregate in the ponds, where the males compete for females. The courtship ritual involves croaking, and a successful male grasps the female under the forelegs. During the mating season the males can be recognised by a darkened swelling, the nuptial pad on their 'thumbs'. The actual spawning takes place at night but the courtship rituals are also at daytime. The females, which are generally larger than the males, lay between 1,000 & 2,000 eggsEgg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
which float in large clusters.
Conservation status
Common Frogs are susceptible to a number of diseases, including RanavirusRanavirus
Ranavirus is one of five genera of viruses within the family Iridoviridae, one of the five families of nucleocytoplasmic large DNA viruses . Ranavirus is the only genus within Iridoviridae that includes viruses that are infectious to amphibians and reptiles, and one of only three genera within...
and the parasitic fungus Batrachochytrium dendrobatidis
Batrachochytrium dendrobatidis
Batrachochytrium dendrobatidis is a chytrid fungus that causes the disease chytridiomycosis. In the decade after it was first discovered in amphibians in 1998, the disease devastated amphibian populations around the world, in a global decline towards multiple extinctions, part of the Holocene...
which has been implicated in extinctions of amphibian species around the world. Loss of habitat and the effect of these diseases has caused the decline of populations across Europe in recent years. It is thought that the spread of the Chytridiomycota
Chytridiomycota
Chytridiomycota is a division of the Fungi kingdom. The name is derived from the Greek chytridion, meaning "little pot", describing the structure containing unreleased spores. In older classifications, chytrids were placed in the Class Phycomycetes under the subdivision Myxomycophyta of the...
fungus has been facilitated by the effects of global warming. The common frog is listed as a species of Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
on the IUCN Redlist of Threatened Species.
Predators
Tadpoles are eaten by fish, beetles, dragonfly larvae and birds. Adult frogs have many predators including birds of prey, crowCrow
Crows form the genus Corvus in the family Corvidae. Ranging in size from the relatively small pigeon-size jackdaws to the Common Raven of the Holarctic region and Thick-billed Raven of the highlands of Ethiopia, the 40 or so members of this genus occur on all temperate continents and several...
s, gull
Gull
Gulls are birds in the family Laridae. They are most closely related to the terns and only distantly related to auks, skimmers, and more distantly to the waders...
s, duck
Duck
Duck is the common name for a large number of species in the Anatidae family of birds, which also includes swans and geese. The ducks are divided among several subfamilies in the Anatidae family; they do not represent a monophyletic group but a form taxon, since swans and geese are not considered...
s, tern
Tern
Terns are seabirds in the family Sternidae, previously considered a subfamily of the gull family Laridae . They form a lineage with the gulls and skimmers which in turn is related to skuas and auks...
s, heron
Heron
The herons are long-legged freshwater and coastal birds in the family Ardeidae. There are 64 recognised species in this family. Some are called "egrets" or "bitterns" instead of "heron"....
s, pine marten
Pine Marten
The European Pine Marten , known most commonly as the pine marten in Anglophone Europe, and less commonly also known as Pineten, baum marten, or sweet marten, is an animal native to Northern Europe belonging to the mustelid family, which also includes mink, otter, badger, wolverine and weasel. It...
s, stoat
Stoat
The stoat , also known as the ermine or short-tailed weasel, is a species of Mustelid native to Eurasia and North America, distinguished from the least weasel by its larger size and longer tail with a prominent black tip...
s, weasel
Weasel
Weasels are mammals forming the genus Mustela of the Mustelidae family. They are small, active predators, long and slender with short legs....
s, polecats
European polecat
The European polecat , also known as the black or forest polecat , is a species of Mustelid native to western Eurasia and North Africa, which is classed by the IUCN as Least Concern due to its wide range and large numbers. It is of a generally dark brown colour, with a pale underbelly and a dark...
, badger
Badger
Badgers are short-legged omnivores in the weasel family, Mustelidae. There are nine species of badger, in three subfamilies : Melinae , Mellivorinae , and Taxideinae...
s and otter
Otter
The Otters are twelve species of semi-aquatic mammals which feed on fish and shellfish, and also other invertebrates, amphibians, birds and small mammals....
s.
Some frogs are killed, but rarely eaten, by domestic cats, and large numbers are killed on the roads by motor vehicles.