European tree frog

The European tree frog is distributed in Northwestern Africa, in the Middle East to Central Iran, in Western and Central Europe to Southern Sweden in the north, and in the southwestern half of Eastern Europe. In Bulgaria it is found throughout the country up to an altitude of 1 300 m, but is found in Rila at an altitude of 2 300 m. It is distributed the subspecies H. a. arborea.

The adult individuals reach a size of 30-40 mm, rarely over 45 mm. The smooth, shiny, usually deciduous back is separated from the white-yellowish to grey belly by a dark stripe. The hind legs are much larger and stronger than the front ones. The head is rounded, the pupil is shaped like a horizontal ellipse, and the eardrum is clearly visible. Males differ from females in the large brown-yellow sound resonators in the throat.

The European tree frog prefers wetlands – mixed and deciduous forests, mountain meadows, city parks, most often near stagnant water bodies. It feeds mainly on insects, most of which are flying and jumping.

After the breeding season in the spring, the frog remains close to the ponds where the eggs are laid, often on the leaves of the papyrus. In mid-summer it moves on the leaves of deciduous trees (poplar, linden, alder, etc.), and in many cases reaches the top of the tree. When climbing, it adheres to the extended fingertips, as well as to the sticky skin of the abdomen and throat.

In the skin of its back, the European tree frog has chromatophores that allow it to quickly change color from pale yellow to bluish-black. This depends on the color of the environment perceived by the eyes, its temperature and humidity, as well as the physiological condition of the frog.

Unknown.

The European tree frog is a protected species included in Annex 3 of the Biodiversity Act (BDA) and Annex II of the Bern Convention. The species is also included in Annex III of Council Directive 92/43/EEC of 21 May 1992 on the conservation of natural habitats and of wild fauna and flora (Habitats Directive) and in the IUCN (International Union for Conservation of Nature) Red List of Threatened Species with category Least Concern (LC).

*Note: For the description of amphibians and reptiles is used information from: Golemanski, V. & al. (eds). 2015. Red Data Book of the Republic of Bulgaria. Vol. 2. Animals. BAS & MoEW, Sofia [English ed.: ISBN 978-954-9746-22-8 (IBER – BAS), 978-954-8497-18-3 (MoEW)]; Biserkov, V. (Editor), 2007. A Field Guide to Amphibians and Reptiles of Bulgaria. Sofia, Green Balkans, 196 pp.; the website of the IUCN (International Union for Conservation of Nature).