European common frog (Rana temporaria)

18 February 2016
Rana-temporaria-Foto

It is the most common amphibian species in Europe [4]. It is encountered from the Pyrenees of Spain to the Eastern border of Europe and to Siberia, from the southern Bulgaria to the northern parts of Norway. It was encounteed even at 71° northern latitude in the Scandinavian Peninsula and even up to 2600 m in altitude (7800 feet). [6]

The Geographic Range of Rana temproraia in Europe [4]

The Geographic Range of Rana temporaria in Europe [4]

In Romania it can be encoutered mainly in the mountain regions, as shown by its Romanian vernacular name (red mountain frog). It prefers a certain degree of humidity, a characteristic shared by the mountain fauna and upper water sheds, as it is encountered between 300 and 2000 meters in altitude (900 to 6000 feet). Among Romanian frog species, Rana temporaria is the only one going to the highest altitudes. [2, 3]

The Geographic Range of Rana temporaria in Romania [1]

The Geographic Range of Rana temporaria in Romania [1]

Morphology. It is often mistaken for the agile frog (Rana dalmatina) due to certain similar traits. In the case of this species, the width of the head is larger than its length, the muzzle is rounded and the nostrils are positioned at the same distance from the eye and from the tip of the head. The pupil is horisontal, and the tympanum is well evidentiated. The front limbs fingers are obtuse, the first being longer than the second. The lower limbs are shorter than those of the Rana dalmatina species, the tibial-tarsal articulation in adults reaches the timpanon, the eye or the nostril when streched forward. The subarticular tuberculi are underdevelopped. The internal metatarsal tubercle is poorly developped, rounded or oval. The skin is smooth, with small verucosities. Between the shoulder blades is found a dark coloured glandular formation shaped as an Ʌ. The dorsal-lateral fold is relatively prominent, sligthly arched, starting in the temporal region. The tegument is smooth on the ventral side, the posterior half of the thighs is granulated. Males differetiante from females by stronger front limbs, very well developped during the mating season, and by the presence of the nuptial pads on the first fore finger, a more developped interdigital membrane and by the presence of the two lateral internal vocal sacks. [2, 3]

The colour of the back varies from different brown nouances to yellow-brown, red brown to dark coffee brown. On this background are inserted black, orange or brick red dots or spots. The lower limbs have transversal brown or dark brown stripes and the temporal region has la large dark spot. The upper lip is bordered by a clear line going from the eye to the corners of the mouth. The ventral colour varies from white to yellowish grey. The iris is golden, sometimes presenting brown vernaculations. During the reproductive season the males are getting blueish reflections on the back and on the neck region. [2, 3]

Ecology. The European common frog has a different lifestyle than its peers. Half of its active period is spent in water and half on dry land. The adults are nocturnal yet active specimens are met even at noon. Juveniles and subadults are diurnal. During the spring it is met in the water along side Bombina variegata and Ichthyosaura alpestris. Starting with the month of april it leaves the aquatic environment and lives on dry land, in the forests, in the hay pastures, being even found on cultivated lands. During September-October they are back in the water where they are wintering in groups up to 400-500 individuals, hibernating in the mud on the bottom of the water bodies or under the rocks. [2, 3]

Reproduction. It is the first frog to lay its eggs early in the spring, since the month of March. The amplex is axillar. The brood is deposited in 1-2 piles at the water surface and comprises 1200-2500 eggs. The larvae are developping in 2-3 weeks and are dark brown, almost black. The metamorphosis lasts for 50-90 days. [2, 3]

Legislation. In Romania, species is protected by Law 13 of 1993, Act through which Romania ratified the Bern Convention (Annex 3), the European Directive Directiva Europeana 92/43/EEC (Annex V) as well as by the Emergency Government Order no. 57/2007 regarding the regime of the protected natural areas, the conservation of the natural habitats, wild flora and fauna, approved with further amendments and completions (Annexes IV-B and V-A), being considered a national interest and community interest species requiring a strict protection. [7, 8, 9]

According to the IUCN classification, world wide the species is of least concern (LC), and in Romanian Red Book of Vertebrates the species is noted as vulnerable (VU). [5, 10]

References

1. Cogălniceanu D., Szekely P., Samoilă C., Iosif R., Tudor M., Plăiaşu R., Stănescu F., Rozylowicz L., (2013): Diversity and distribution of amphibians in Romania, Zookeys 296:25-57.

2. Fuhn  I. E.,  (1960):  Amphibia. In: Fauna  R.P.R.,  Vol.  XIV,  Fasc.  1, Editura  Academiei Republicii Populare Române, București. [in Ro]

3. Fuhn I.E., (1969): Broaște, șerpi, șopârle. Editura Științifică, București. [in Ro]

4. Gasc J.P., Cabela A., Crnobrnja-Isailovic, Domen D., Groessenbacher K., Haffner P., Lescure J., Martens H., Marinez Rica J.P., Maurin H., Oliveira M.E., Sofianidou T.S., Veith M., Zuiderwijk A., (1997): Atlas of Amphibians and Reptiles in Europe. Societas Europaea Herpetologica & Museum National d’Histoire Naturelle, Paris.

5. Iftime A., (2005): Reptilia. In: Botnariuc & Tatole (eds): Cartea Roșie a Vertebratelor din România, Editura Academiei Române, București. [in Ro]

6. Merilä J., Laurila A., Laugen A.T., Rasanen K., Pahkla M., (2000): Plasticity in age and size at metamorphosis in Rana temporaria - comparison of high and low latitude populations. Ecography, 23: 457-465.

7. ***Legea 13 din 1993 prin care România ratifică Convenția de la Berna. [in Ro]

8. ***Directiva Europeana 92/43/EEC. [in Ro]

9. ***Ordonanța de Urgență a Guvernului nr. 57/2007 privind regimul ariilor naturale protejate, conservarea habitatelor naturale, a florei și faunei sălbatice, aprobată cu modificări și completări ulterioare. [in Ro]

10. *** www.iucnredlist.org

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