Common frog
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Common frog ( Rana temporaria ), younger female |
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| Rana temporaria | ||||||||||||
| Linnaeus , 1758 |
The common frog ( Rana temporaria ) belongs to the genus of real frogs in the family of real frogs . Other trivial names that are rarely used any longer include "Taufrosch" and "Märzfrosch". Together with similar looking and also more terrestrial living species such as the agile frog and marsh frog he is also referred to collectively as " brown frogs out". The common frog was named " Lurch of the Year 2018 " in Germany and Austria .
features
The head-body length of adult animals ( adults ) reaches a maximum of eleven centimeter, with the females due to the slightly later onset of sexual maturity , on average, are slightly larger than males. Most of the specimens, however, are between seven and nine centimeters tall and look quite clumsy. The top can be colored yellow, red or dark brown. In some animals it is only slightly drawn, others have irregular black spots that can sometimes almost obscure the basic color. The two back gland ridges approach a little in the shoulder area. The bilateral, characteristically triangular temple spot with the eardrum inside is , as with all brown frogs, distinctly dark brown. The horizontal stripes of the hind legs are also a feature of all brown frogs. The underside of the male is whitish-gray and mostly unspotted, while the female is often yellow and marbled with a reddish tinge. The tip of the snout is bluntly bevelled and rounded in plan view, the pupil is elongated and aligned horizontally. The inner heel hump on the sole of the foot appears small and soft in this species.
The front legs of the males are much stronger than those of the females. This is due to the reproductive behavior, as the animals have to hold on to the back of the females for days in an axillary grip ( amplexus ). At spawning time, the males sometimes appear a bit "wobbly" due to the accumulation of lymph fluid and can even appear slightly bluish (but not as intense as male Moor Frogs). During this phase, they develop dark, rough heat calluses on their inner fingers . A so-called spawning rash consisting of whitish “pimples” in the area of the flanks and hind legs can be observed in the females during spawning time.
Reproduction and Individual Development
In early spring - in Central Europe mostly mid to late March - the adult animals awakened from winter rigor find themselves in the spawning waters after having migrated there at night in frost-free rainy weather. The males keep an eye out for the females arriving a little later on the bank and in the shallow water. In addition, they utter mating calls that are generated with two inner sound bubbles , but are relatively quiet. The call can be described as a dull growl or hum. The following is an example of pairing calls:
Since the population always finds itself in the same body of water, the calls for the organization of the spawning society play a lesser role than with "stray" frogs with changing spawning grounds and therefore do not have to be so loud. Furthermore, the common frog is a so-called "explosive spawner" whose reproductive phase is very concentrated over a few days. The mating calls can therefore only be heard briefly, both during the day and - increasingly - after dark. However, some stragglers still call after the main spawning phase.
Reproduction often takes place in preferred - vegetation-rich and sunny - bank sections of waters, so that there can be accumulations of sometimes hundreds, rarely even thousands, of spawning clumps on several square meters. The spawning balls of the common frog are particularly large and contain around 700 to 4400 (mostly between 1000 and 2500) eggs. A female usually only lays one ball of spawn, rarely two. When the spawn emerges from the cloaca of the female, it is inseminated by the male sitting on his back. The mass spawning sites mentioned above are far less common today than they were a few decades ago. In a study from northwest Germany, the average number per spawning water was 41 spawning balls; a third of the spawning sites evaluated even had fewer than 10 egg clumps.
The eggs are almost black in color, only with a tiny lightening at the lower egg pole. The egg diameter (without surrounding jelly) is 1.7 to 2.8 millimeters; the jelly has a diameter of 8 to 10 millimeters in "ripe" spawn. After spawning, this swells up and the bales usually rise to the surface of the water due to gas formation. They can now be seen clearly as large, floating “flat cakes”. The jelly has a kind of burning glass function and so the upper and middle eggs heat up faster than the ones below and the corresponding seedlings develop more quickly. On the other hand, there is a risk of freezing over and dying off in spring, especially for the upper and outer eggs of a spawning ball. If a spawning lump is turned upside down (with the lower, light egg poles pointing upwards), this can also lead to death.
Depending on the ambient temperature, the larvae , which are 6 to 9 millimeters long, hatch after a few days or only four weeks. In the older, buoyant tadpoles, the upper fin edge of the tail reaches at most to the middle of the trunk. The oar tail reaches a maximum of twice the body length and ends rather bluntly. The basic color is brown with copper to bronze colored spots; the total length finally reaches around 46 millimeters. The aquatic development up to the metamorphosis to land animals takes about two and a half to three months, depending on the external conditions, so that in Central Europe most of the young frogs left the water in mid to late June. In high mountain areas, spawning times and larval development can be considerably delayed. The eggs are then sometimes only laid in summer. Some larvae then no longer metamorphose before winter, but hibernate aquatically (compare for example: Wurzeralm ).
Common frogs become sexually mature at two to three years of age (under unfavorable conditions only four years old), whereby they increase their body mass especially in the first year of life after the transformation. On average, males are somewhat more sexually active than females of the same age.
Habitat and way of life
Spawning waters include a wide range of stagnant or slowly flowing waters. However, preference is given to shallower still waters in the sun, such as small ponds and ponds (including garden ponds), which are seldom allowed to dry out, or cattle watering places in grassland areas. As spawning substrate are flood grass for example from the flood ends swaths particularly popular. After laying eggs, the animals usually leave the water very quickly and move on to rural life. For example, grassland, fringing biotopes, bushes, river banks, forests, gardens, parks and moors are now populated as habitats . At night the frogs hunt for insects (for example beetles and foliage locusts ), woodlice , worms , spiders and nudibranchs , and during the day they hide in damp places between vegetation or under stones or dead wood . Hibernation sometimes takes place on the bottom of bodies of water (then often collectively), but mostly terrestrial in holes in the ground and similar frost-free shelters. Before that, in autumn, the animals have usually already migrated a little towards the spawning water or even use it for wintering in cold rigor - so summer habitat and wintering quarters are not necessarily identical.
Among the main predators of the common frog include various bird species such as black and white stork , buzzard , spotted eagle , red and black kite , eagle owl , tawny owl , barn owl and the Blackbird . The grass snake , various trout fish , wild boar , red fox , badger , polecat and brown rat should also be mentioned. The tadpoles, for example, are stalked by larvae of dragonflies and yellow beetles .
Common frogs rarely live to be ten years old under natural conditions; most of them die much earlier due to the numerous predators, losses during winter, diseases and civilizational factors (road traffic, environmental toxins, etc.). One specimen lived to be 18 years of age in captivity.
distribution
The common frog is represented in most of Europe . The area extends from the northern edge of the Iberian Peninsula to France and the British Isles - the species was artificially introduced to Ireland around 300 years ago - across Central Europe and the European part of Russia to beyond the Urals to western Siberia and northern Kazakhstan . In the north all of Scandinavia is settled up to the North Cape . In contrast, there are larger distribution gaps in the Mediterranean region of southern Europe, where other species of brown frogs occur instead, and between Hungary and the Black Sea . The southernmost observations come from northern Greece . Common frogs have been spotted in northern Switzerland up to 2630 meters above sea level.
In Germany , the common frog is more or less common from the North and Baltic Sea coasts to the Alps . However, depending on the landscape structure, there are very different population densities (compare: endangerment). For example, there are no common frogs in monotonous agricultural landscapes such as the eastern Uckermark , in the Oderbruch , on the Querfurter Platte and in the Weißenfelser farmland; The Hellwegbörden , the south-eastern Münsterland and other regions also have low abundances . Also noteworthy is the fact that within the north German lowlands a west-east divide is clear: While in Lower Saxony the common frog, the dominant far Braunfroschart is, can already at the lower middle same -Niederung locally the Moorfrosch assume this role. In the north-eastern lowlands (eastern Mecklenburg-Western Pomerania , eastern Brandenburg ) the moor frog is more common than the common frog in many places.
In Austria , the common frog is common and widespread almost everywhere. Area gaps can be seen in the eastern lowlands.
In Switzerland the common frog is the most common frog; only in southern Ticino and in the Geneva area there seem to be lower abundances and distribution gaps.
Subspecies
The nominate form Rana temporaria temporaria colonizes almost the entire distribution area. Because of the great external variability, numerous varieties have been described. In addition to the nominate form, around four are recognized as subspecies . It is noticeable that their occurrences are all concentrated in narrow mountainous regions on the south-western edge of the entire area . In the mountainous regions of north-west Spain, the long-legged and smaller subspecies R. t. parvipalmata , in the Spanish Pyrenees R. t. aragonensis , in the French Eastern Pyrenees R. t. canigonensis and in the French Alps between 700 and 2000 m above sea level R. t. honnorati . Other forms and subspecies described earlier are now partially assigned to other species of brown frog. More recently, for example, the Pyrenean frog ( Rana pyrenaica Serra-Cobo, 1993). The (under) speciation in the south-west was evidently promoted by climatic fluctuations and the resulting geographic isolation in the corresponding mountain regions.
Fossil and archaeological evidence
The oldest fossil finds of the common frog in Central Europe date from the late Upper Pliocene about two million years ago. The species was found fossilized in the mud of a sinkhole lake near Kaltensundheim in the Thuringian Rhön together with remains of the mammoth Mammut borsoni . For the Pleistocene , Rana temporaria is one of the most common records of fossil frogs - not only from warm-time , but also from cold-age and even highly glacial phases (in the ice-free areas).
Archaeological finds in the local area of Kutná Hora (Czech Republic) show that the prehistoric population in this region already ate frogs' legs . This is shown by approximately 700 bones found in these animals.
Hazard and protection
In recent years, local and regional population declines have been noted in various parts of Europe (Great Britain, Spain, Switzerland, Austria, Germany). In some regions that are monotonous in terms of landscape structure and intensively cultivated by humans, one can only observe small spawning societies instead of hundreds of spawning frogs in one body of water, as was previously the case. In the Red List of Endangered Animals in Germany, this apparent “commonplace species” was therefore included in the “Pre-Warning List” category in the meantime (1998 to 2009). In addition to habitat destruction, motor vehicle traffic on the dense road network is an important general source of danger: When migrating between the sub-habitats, including from winter quarters to spawning waters, countless common frogs are run over alongside other amphibians, such as common toads .
Legal protection status (selection)
- Fauna-Flora-Habitat Directive (FFH-RL): Annex V (species can be the subject of administrative measures)
- Federal Species Protection Ordinance (BArtSchV): particularly protected
National Red List classifications (selection)
- Red List Federal Republic of Germany: not endangered
- Red list of Austria: NT (threat of danger)
- Red list of Switzerland: LC (not endangered)
literature
- Josef Brzoska, Wolfgang Walkowiak, Hans Schneider: Acoustic communication in the grass frog (Rana t. Temporaria L.): calls, auditory thresholds and behavioral respones. Journal of Comparative Physiology, Volume 118, 1977, pp. 173-186.
- Stefan Holler: Convergence of afferent and commissural signals from the semicircular canals and the otolith organs in the common frog (Rana temporaria) , Universitäts-Bibliothek-Ludwig-Maximilians-Universität München 2001, DNB 963933078 (Dissertation University of Munich, Faculty of Biology, July 24, 2001, 65 pages , Supervisor: Hans Straka full text online , PDF, free of charge, 65 pages, 4.9 MB).
- Andreas & Christel Nöllert: The amphibians of Europe. Franckh-Kosmos, Stuttgart 1992, ISBN 3-440-06340-2 .
- Martin Schlüpmann & Rainer Günther: Common Frog - Rana temporaria LINNAEUS, 1758. - In: Rainer Günther (Ed.): The amphibians and reptiles of Germany. G. Fischer, Jena 1996, pp. 412-454, ISBN 3-437-35016-1 .
- Hans Schneider: Bioacoustics of the Froschlurche - native and related species. With audio CD. Supplement to the Zeitschrift für Feldherpetologie 6. Laurenti Verlag, Bielefeld 2005. ISBN 3-933066-23-9 . Audio samples: 11.1,11.2.
- Heribert Wolsbeck, Hubert Laufer, Helmut Genthner: Grasfrosch, Rana temporaria LINNAEUS, 1758. In: Hubert Laufer, Klemens Fritz & Peter Sowig (eds.): The amphibians and reptiles of Baden-Württemberg. Ulmer, Stuttgart 2007, pp. 431-450. ISBN 978-3-8001-4385-6 .
Web links
- Photos of the common frog at www.herp.it
- Information on the common frog in Austria at www.herpetofauna.at
- Information on the common frog, coordination office for amphibian and reptile protection in Switzerland (karch)
- Rana temporaria in the endangered Red List species the IUCN 2009. Posted by: Kuzmin, S. et al ., 2008.
Individual evidence
- ↑ For example, overview by Heribert Wolsbeck, Hubert Laufer & Helmut Genthner: Grasfrosch, Rana temporaria Linnaeus, 1758. In: Hubert Laufer, Klemens Fritz & Peter Sowig (eds.): Die Amphibien und Reptilien Baden-Württemberg. - Ulmer-Verlag, Stuttgart 2007, pp. 431-450. ISBN 978-3-8001-4385-6 .
- ↑ Christian Fischer: Stock sizes of common frog spawning societies ( Rana temporaria ) in the northwest German lowlands - evaluation of spawning ball counts in 448 bodies of water. - Zeitschrift für Feldherpetologie 5, pp. 15-30. Laurenti-Verlag, Bochum 1998. ISBN 3-933066-04-2
- ↑ Hans Heusser: The importance of the external situation in the behavior of some amphibian species. - Rev. Suisse Zool. 68, pp. 1-39 (1961).
- ↑ Josef Blab: Studies on ecology, space-time integration and function of amphibian populations. - Series of publications for landscape management and nature conservation, issue 18, Bonn-Bad Godesberg, 1978.
- ^ Dieter Glandt: The seasonal migrations of the Central European amphibians. - Bonn zoological contributions 37 (1986), volume 3, pp. 211-228. ( online ( Memento of the original from April 7, 2014 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this note .; PDF; 7.1 MB)
- ↑ MN Denisowa (1969), cited by Schlüpmann & Günther (cf. Lit.)
- ↑ Kurt Grossenbacher: Distribution atlas of the amphibians of Switzerland. - Doc. Faun. Helvetiae, Vol. 7 (1988).
- ↑ Thomas Bader at www.herpetofauna.at ( Memento of the original from July 20, 2006 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Kurt Grossenbacher at www.karch.ch ( Memento of the original from October 3, 2006 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Michael Veith, Joachim Kosuch & Miguel Vences: Climatic oscillations triggered post-Messinean Speciation of Western Palearctic brown frogs (Amphibia, Anura, Ranidae). - Molecular Phylogenetics and Evolution 26 (2003), pp 310-327.
- ↑ Rana temporaria in the database “Amphibian Species of the World” of the American Museum of Natural History ( Memento of the original from February 23, 2009 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Gottfried Böhme: On the historical development of the Herpetofaunen of Central Europe in the Ice Age (Quaternary). - In: Rainer Günther (Ed.): The amphibians and reptiles of Germany. - G. Fischer-Verlag, Jena, 1996, pp. 30-39. ISBN 3-437-35016-1
- ↑ R. Kysely: Frogs as part of the Eneolithic diet: archaeological records from the Czech Republic (Kutna Hora-Denemark site, Rivnac Culture). - Journal of Archaeological Science 35 (2008): 143-157. ( Report on this at archaeozoo.wordpress.com (Engl.))
- ↑ Common frog at www.wisia.de
- ↑ Federal Agency for Nature Conservation (ed.): Red list of endangered animals, plants and fungi in Germany 1: Vertebrates. Landwirtschaftsverlag, Münster 2009, ISBN 978-3-7843-5033-2
- ↑ Online overview at www.amphibienschutz.de
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