AmphibiaWeb - Rana arvalis


(Translations may not be accurate.)

Rana arvalis Nilsson, 1842
Moor Frog
Subgenus: Rana
family: Ranidae
genus: Rana
Rana arvalis
© 2013 Andreas Nöllert (1 of 138)

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Conservation Status (definitions)
IUCN Red List Status Account Least Concern (LC)
National Status Red Data Book of Latvia.
Regional Status Bern Convention (Annex 3); Red Data books of Rostov Province and Buryatia Republic, both in Russia.
conservation needs Access Conservation Needs Assessment Report .


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A medium to large frog. Vomerine teeth present. Posterior part of the tongue free and forked. Toes webbed. Omosternum and sternum ossified. Pupil of the eye horizontal. Snout more or less terminating in a point. Male with internal guttural vocal sacs. Shin (knee to ankle) shorter than body by 1.9-2.6 times. When the shins are positioned perpendicularly to the body axis, the heels contact or overlap. When the hind leg is stretched along the body, the tibio-tarsal articulation usually reaches the eye, nostril, tip of snout or even slightly exceeds it. Inner metatarsal tubercle high, shorter than the first toe by 1.1-2.3 times. Flank and thigh skin smooth.

Dorsal coloration grey, light-olive, brown, yellowish or rufous. Chevron-shaped (^) dark glandular spot on the neck. Dark spots of 1-3 mm on dorsal and lateral surfaces vary considerably in number, arrangement and size. Temporal spot large. Light middorsal band with regular edges frequently present, often reaches the middle or the tip of the snout. Belly white or yellowish without pattern or with pallid-brownish or greyish spots on the throat and chest.

Male differs from female by having nuptial pads on the first finger, paired guttural vocal sac and, during the breeding season, light-blue coloration of the body (the female is brown or rufous). Subspecific differentiation needs further study. The species belongs to the "brown frog" group.

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Austria, Belarus, Belgium, China, Czech Republic, Denmark, Estonia, Finland, France, Germany, Hungary, Kazakhstan, Latvia, Lithuania, Moldova, Republic of, Netherlands, Norway, Poland, Romania, Russian Federation, Slovakia, Slovenia, Sweden, Switzerland, Ukraine

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View distribution map in BerkeleyMapper.
amphibiandisease logo View Bd and Bsal data (77 records).
Northern margin of the range extends from the Southwestern Norway, Central Sweden and Finland to Northwestern Russia. There, the margin runs from Murmansk Province, then approximately along the line: Arkhangelsk Province (Pinezhskii Nature Reserve - south of the Kanin Peninsula - Nenets Autonomous County) - Komi Republic (Vorkuta City: 67º29'N, 64º00'E) - Tyumen Province (Yamal-Nenets Autonomous County, Kharvuta Settlement on the Khadyta-Yakha River) - Krasnoyarsk Region (Taimyr Autonomous County). Then the margin runs south-southeastwards from the Enisei River to the Chuna River in Krasnoyarsk Region and Irkutsk Province (Boguchan District) and to Irkutsk City (52º19'N, 104º18'E). The frog inhabits the valleys of the Lena River and its tributaries from Irkutsk City northeastwards to Sanyyakhtakh Settlement in Yakutia (ca. 60º40'N, 124ºE). The frog was recorded also in Olekminskii Nature Reserve (58º45'N, 122º20'E). From the valley of the Lena River in Irkutsk Province (Kirensk Settlement: 57º45'N, 108º04'E), the margin runs southwards on the northern shore of Lake Baikal near the Baikalskii Ridge. To the south of Baikal Lake, in Buryatia, the frog is distributed from the Irkut River northeastwards along the southern shore of the Baikal to Barguzinskii Nature Reserve (54º23'N, 109º05'E). The southern margin of the range runs approximately from the Southern France and Germany, Northern Yugoslavia, Central Bulgaria, then by the Southern Ukraine approximately along the line: Odessa Province (Kiliya District) - Nikolaev Province - Kherson City - Zaporozhie Province - Donetsk Province. Then the margin runs in Russia eastwards to Rostov Province and northeastwards to the south of Volgograd Province. Then it runs eastwards in Kazakhstan approximately along the line: Uralsk City (51º13'N, 51º22'E) - Aktyubinsk City - Turgai Province - Tselinograd Province - Karaganda Province - Semipalatinsk City area (50º27'N, 80o14'E). Then the margin turns southwards to Ayaguz Town (47º58'N, 80º26'E) and Taldy-Kurgan Province (to the west of Alakol Lake, Uch-Aral Settlement: ca. 46º20'N, 80º40'E), then to Altai Mountains in the north of China and Mongolia.

The Moor Frog inhabits the zones of tundra, forest tundra, forest, forest steppe, and steppe. In Europe, the frog generally inhabits drier and more open sites than the Common Frog (Rana temporaria), including forest edges and glades, swamps, meadows, fields, bushlands gardens, etc. In Siberia, the species lives mainly in open swamps. The frog penetrates tundra and steppe in association with arboreal vegetation, primarily along intrazonal landscapes of river valleys. At the southern and northern limits of its range, in tundra, forest, and true steppes, the species lives near water bodies: rivers, lakes etc. There the populations of R. arvalis seem to be isolated. Spawning and early development occurs in stagnant waters, including lakes, ponds, swamps, puddles and ditches, which are from several meters to some hectares in area and from few centimeters to two meters in depth.

Life History, Abundance, Activity, and Special Behaviors
Rana arvalis is one of the most abundant amphibians in the Central and Eastern Europe, as well as West Siberia. There, its population density reaches several hundred individuals per hectare. Local density may be higher, such as in breeding ponds where 15-20 individuals per 1 m2 can be found. In the forests of the center of European Russia, it usually prefers more open habitats than the sympatric Common Frog, and is rarer than the latter in the north, whereas the proportion gradually changes to the south and southeast in favor of R. arvalis,> and at the south of the zone of sympatry it significantly outnumbers R. temporaria. The proportion of the two species varies also by year, and in some areas the dominance of one or another species alternates. Density-dependent regulation is important in overcrowded tadpole groups, where several hundred individuals per liter sometimes occur, as well as in the dense groups of recently metamorphosed froglets. However, habitat peculiarities and fluctuations in weather and climate appear to be more important in terms of the overall population dynamics.

The Moor Frog in the European region is probably a more thermophilous species than the sympatric Common Frog. It frequently occurs in warmer and drier microhabitats. Hibernation extends from September - November to February - June, in dependence on latitude. The earliest appearance (February) and latest disappearance (late November - December) takes place in the plain areas at the southwest of the species distribution, whereas the latest appearance (June) and earliest disappearance (September) is in the Polar Urals. Reproduction occurs from March - June, usually some days after the end of hibernation. Males form breeding choruses. Amplexus is pectoral (axial). The total duration of the breeding season within a pond is 3-28 days. Eggs are deposited in shallow, well-warmed sites, during both day and night. However, spawning by the Moor Frog peaks later than that of the Common Frog; it prefers more open and shallow wetlands for reproduction. The clutch contains 500-3000 eggs deposited usually in one, rarely in two clumps.

Metamorphosis occurs from the beginning of June to October in different regions. In general, the duration of development before metamorphosis shortens in the north and the south of the distribution. Formation of dense schools of tadpoles, where density-dependent regulation of development takes place, is typical. The density does not influence larval survival rate directly but influences the probability of successful metamorphosis because fast developing tadpoles often complete their transformation, while slowly developing individuals die in drying wetlands. "Delayed" larvae metamorphosed into froglets at significantly smaller body sizes and possessed less energy reserves. This may be evidence of lower viability. However, in good living conditions, their compensatory growth may enable them to reach the size of specimens from early clutches. However, this compensatory growth takes place relatively seldom, and more often the growth does not depend on individual size after metamorphosis. Sexual maturity is attained in the 2nd-5th year of life. On average, females mature later and have a longer life span than males. The maximum life span recorded for this species is 11 years old.

Moor Frog tadpoles eat Chlorophyta, Cladocera, and other algae, higher plants, detritus, as well as small amounts of invertebrates. Recently metamorphosed froglets forage on Acarina, Collembola and other microarthropods. Adults consume mainly terrestrial prey, aquatic invertebrates (slugs, diving beetles etc.) are consumed in smaller proportions and, as a rule, irregularly. Feeding ceases during the reproductive season.

Trends and Threats
The species is generally neither declining, nor threatened. However, isolated peripheral populations may be vulnerable from human influences and deserve special attention or protection. Only in some areas highly transformed by people (destruction of breeding ponds and adjacent terrestrial habitats, especially during urbanization, recreation and the overpasturage of cattle) have the populations declined.

Relation to Humans
In addition to the above mentioned anthropogenic factors of the species local declines, industrial pollution also negatively affects populations, including those living in cities. It leads to an increase of frequency of morphological abnormalities and disturbances in embryonic and larval development. Nevertheless, R. arvalis is a species easily adaptable to life in anthropogenic conditions. Some urban populations of this species are fairly large and safe, if suitable habitats are available. Some forms of human activity lead to an increase in the frog's number and their dispersal. For example, the construction of forest rides with numerous artificial holes filled with water.


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Bannikov, A. G., Darevsky, I. S., Ishchenko, V. G., Rustamov, A. K., and Szczerbak, N. N. (1977). Opredelitel Zemnovodnykh i Presmykayushchikhsya Fauny SSSR [Guide to Amphibians and Reptiles of the USSR Fauna]. Prosveshchenie, Moscow.

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Originally submitted by: Sergius L. Kuzmin (first posted 1999-11-10)
Edited by: Meredith J. Mahoney, Michelle S. Koo (2022-08-16)

Species Account Citation: AmphibiaWeb 2022 Rana arvalis: Moor Frog <> University of California, Berkeley, CA, USA. Accessed Jul 19, 2024.

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Citation: AmphibiaWeb. 2024. <> University of California, Berkeley, CA, USA. Accessed 19 Jul 2024.

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