The green tree frog, or God's frog (Hyla arborea) is in Slovenia the one and only species among the 218 species of the genus Hyla that live on Earth. It is a small amphibian with smooth skin and a charming appearance, which, with the help of adhesive pads at the ends of its toes, deftly climbs along the branches and leaves of shrubs, trees or reeds and similar tall herbs. The adhesive pads enable it to grip excellently even on completely smooth surfaces, such as glass.
Its body length reaches 3 to 5 cm. On the back it is bright green, with a dark brown stripe running along the sides behind the eyes, usually yellow-edged. Its ventral side is whitish. Females have white throats, males have golden-yellow throats. The green tree frog adapts the color of its body to the surroundings, and thereby hides more easily from the watchful eye of predators or approaches its prey unseen. When it wakes from winter sleep, hibernation, its back can be brownish gray, but as the vegetation begins to green, its back also becomes greener. The light green color over the summer can gradually change to brown, and in autumn the frog again dons a coat of grayish color. Its large bulging eyes have a brown-gold iris and a horizontally placed pupil.
The green tree frog is widely distributed in Slovenia, and occurs up to 800 m above sea level. Adults live on the margins of forests, in clearings and on marsh meadows with tall herbaceous plants. They are active during the day, then in the canopies of shrubs or trees or on the stalks of tall stems they lie in wait for various flying insects and their larvae.
They very much like to sunbathe and also reproduce in smaller, sunlit bodies of water. From April to June the loud chorus of the males can be heard several kilometres away. The ringing ke-ke-ke-ke-ke or rega-rega-rega-rega-rega in warm and humid evenings attracts females, which stay in the water only until they lay their spawn. Breeding takes place at sunset; at that time the females lay on plants in the water 2 to 3 cm wide spherical spawn, and the male fertilizes the eggs as they are laid. Green tree frogs avoid breeding in waters with fish! After spawning, adult green tree frogs return to land, where they generally are no more than 300 m from the spawning area, under stones or in rock crevices to overwinter.
In Slovenia the green tree frog is protected and as a vulnerable (V) species is listed on the Red List!
