European tree frog

Description

The snout-vent length of the European tree frog is 3 to 4.5 cm, in females also up to 5 cm. Body weight in the male can vary from 3.5 to 7 g, and in the female frog from 6 to 9 g, depending on the season. The head is wider than long; the sides of the head slope steeply, and the snout is correspondingly blunt-angled. The strongly protruding eyes have horizontal elliptical pupils, the sometimes dark speckled iris glows golden yellow. In the dark, the pupils dilate to fill almost the entire visible eyeball. The tympanic membrane is clearly visible and about half the size of the eye. Ear gland bulges (parotids), such as in the common toad, are absent. The front limbs are quite short and have four fingers each with adhesive discs (see below) at the ends, the hind feet have five toes each. The throat of males is yellow to yellow-brown in color and wrinkled, that of females whitish to light gray and slightly granular. Males have a large, yellowish or brownish, throat-shaped vocal sac.

skin, colouration

The skin surface is smooth and may be conspicuously shiny, especially when sunbathing. The upperparts are usually bright green in color. The belly and the inner surfaces of the extremities are predominantly white to light gray and granular. On both flanks, a dark stripe extends from the nostril over the tympanic membrane to the groin region. There it curves upwards and forms a so-called hip loop. Especially in the area of this hip loop, the flank stripe runs a bit differently in each individual. The hip loop is also called a groin loop, because the black lateral stripe ends in the groin region and does not form a loop. 

European tree frogs can take on quite a varied color appearance in rapid succession. Variation ranges from light gray to yellowish to dark green. 

Habitat

Depending on seasonal activity, tree frogs occupy very different aquatic and terrestrial subhabitats. The following habitat types and structures are relevant for a successful and sustainable life cycle:

aquatic subhabitats - Reproductive habitats

• FFish-free, sunlit small water bodies (pools, ponds, pressure/qualm water areas, bracks, flood depressions and oxbow lakes in river and stream floodplains, temporarily flooded grassland depressions, also water bodies in quarry pits).
• Vegetated, amphibious shallow and alternating water zones (as metamorphosis and maturation habitat for juvenile specimens).
• Aquatic and marsh plant communities of pondweeds (Potamogeton spec.), floodplain grasslands (especially Glyceria fluitans), acid grass fringes (sedges, rushes), and reed beds.

terrestrial habitats - daytime hiding places, feeding habitats

• Extensively managed wetlands and wet meadows as foraging habitat for growing and adult specimens.
• Wooded strips, reedbeds and watercourse-accompanying high herbaceous vegetation as perching and calling sites outside the mating season and as biotope network structures.
• Riparian forests, copses, moist coppice forests with plenty of sunlight, reed beds on sites close to groundwater.

As perching sites, adults and juveniles choose shrubs and even tree tops, especially various herbaceous plant species. In the literature, blackberry bushes are often mentioned; according to our own observations, the large leaves of burdock (Arctium spec.) are also particularly popular for sunbathing. However, it is not clear whether these structures are specifically preferred by the frogs or whether it is just easier to discover them on the large leaf surfaces.

The text is a translation of an excerpt from Wikipedia (https://de.wikipedia.org/wiki/Europäischer_Laubfrosch). On wikipedia the text is available under a „Creative Commons Attribution/Share Alike“ licence. Status: 29 June 2021