Mediterranean Tree Frog

Hyla meridionalis usually grows to 50 mm, with females up to 65mm in length. Slender, long-legged tree frog, with smooth skin. The head is broader than long. Adhesive discs on all digits, with those on the fingers being larger than on the toes. The back is mostly green, but a yellowish, gray, brown or spotted coloration also occurs. Color change is physiological. The venter is whitish. A dark stripe is present from the nostril across the eye and tympanum to the shoulder. The iris is brownish golden, the pupils are horizontal. The tympanum is clearly visible and about half the diameter of the eye. Males posses a vocal sac which can be inflated to a size half the snout-vent length. At rest, the vocal sac is longitudinally folded and yellow to brownish in color. The throat of females is somewhat lighter than the venter. Taken from Noellert and Noellert (1992) and Bons and Beniez (1996).

The general area occupied by H. meridionalis in Europe extends from S France and NW Italy, to S Portugal and Spain, including Menorca, in the Balearic Islands, and the Canary Islands. Its European range includes two main general groups of populations. A southern group occupies S and W Spain and Portugal, and a northern group extends from NE Spain and S France to NW Italy. The southern group occupies mainly Central and S Portugal and SW Spain; it is prolonged eastwards by three discontinuous groups of populations. One group occurs along the Spanish Mediterranean coast from the provinces of Huelva and Cádiz to the region of Murcia. The second group inhabits Sierra Morena on the southern slopes of the Central Plateau. And the third group runs along the Tajo River, which acts as a corridor for the penetration of the western populations inside the Central Plateau, across the provinces of Toledo and Avila. The northern group of populations is separated from the southern one by a long gap across the E Spanish Mediterranean coast from Murcia to Cataluña. This group shows populations in the eastern portions of Cataluña in NE Spain, in a wide area of S France, and across the Liguria region to the province of Genova in NW Italy. The populations from S France are widely spread along the Mediterranean coast, running along the Rhône Valley as far as the Dr6me, and along the southeastern slopes of the Massif Central as far as the northwestern portions of the Charente-Maritime département. Some isolated populations have been reported from the south of the Landes region, in the département of Pyrenées-Atlantiques in France and in the Basque Country in Spain. H. meridionalis is also present in the Balearic Archipelago but restricted to Menorca Island, where it occurs throughout the island. Little is known of the northern limits of the range. In Iberia its distribution seems to be limited by the cold and dry regions of the Central Plateau, but the northwestern and eastern limits along the coasts are uncertain. There is no actual continuity between the populations of the northern Mediterranean coast and the southern Mediterranean ones. The northern and the southwestern limits of its distribution in France are uncertain. H. meridionalis is usually found at low altitudes, from sea level up to 450 m in Portugal and 650m in France. Exceptionally it can exceed 1000 m in NE Spain (Montseny, province of Barcelona), and S France (Gasc 1997).H. meridionalis also occurs in NW Africa. Here it occurs in the humid Mediterranean regions of the Mahgreb. In Morocco it occurs in the Moyen et Haut Atlas. It is found up to an altitude of 2650 m in Oukaimedene in the Haut Atlas (Schleich et al. 1996). A morphologically different form is found in the Anti Atlas Mountains the southernmost part of the range of the species (Bons and Beniez 1996).

Mating occurs in March and April in North Africa, while the European populations mate from April to June (France) or from December to January (Portugal). Males call from water as well as from land and trees. The individual call is a deep, resonant "Cra-a-ar", repeated not much faster than every second and typically much slower (Burton and Arnold 1978). Calling can also occur in duo's, trio's or choruses, and is sometimes deafening. Calling can be heard from kilometers away during the calling peak in the breeding season. Amplexus lasts several hours to some days. Fleeing reactions are greatly reduced in mated couples. For oviposition they prefer plant accumulations near the shore. The female searches an object to attach her eggs to and expulses some spawn. This is the signal for the male to dip his hindbody down and inseminate the eggs. Ovipositionis repeated at many places until the female has no more eggs to expel. Even then she continues to act as before, but when the male notes that there are no more eggs he quits. When breeding is finalized the frogs leave the vicinity of the water and move away into trees etc. where they call mainly during the afternoon or evening hours until aestivation begins. The eggs are 800-1000 in number, deposited in lumps of 10-30 each, mostly on plants, but some sink to the bottom. Ovum diameter is 1.1 to 1.5mm, with a gelatinous envelope of 3-5mm. Tadpoles hatch after 8-10 days with a total length of 5-8mm. The tadpoles have high fins relative to their total length. They grow up to 4cm, with a maximum of 5.5cm. Metamorphosis occurs 3-4 months after hatching. The diet consists of various arthropods like spiders, bugs, beetles, butterflies, flies and ants, which are caught from ambush by day and by foraging at night (Schleich et al. 1996).

The main areas of distribution of the species in SW Iberia and S France seem to maintain a relatively high number of populations, although the rapid destruction of breeding biotopes and the intense use of pesticides, both a consequence of the loss of traditional agricultural methods, could modify the present situation in a short period of time. The populations of the southeastern Mediterranean coast and the isolated populations in the Basque Country could be considered the most endangered populations in Spain. The latter, limited to a few ponds in sandy soil, have recently been recorded again, but the possibilities of continuity appear to be very low (Gasc 1997). Honnegger (1981) notes that the species is suffering from an intensive anti-mosquito campaign along the Mediterranean coast.

Reaches high population densities in banana plantations in the Canary Islands(Schleich et al. 1996).

Rest position - Haute-Garonne France

The Mediterranean tree frog (Hyla meridionalis), or stripeless tree frog, is a species of frog found in south-west Europe and north-west Africa. It resembles the European tree frog, but is larger (some females are up to 65 millimetres (2.6 in) long), has longer hind legs, and the flank stripe only reaches to the front legs (often starting at the eyes, not at the nostrils). The croaking resembles that of H. arborea, but it is deeper and slower.

The Hyla meridionalis generally breed from the end of March through the beginning of July; their breeding is dependent on a few variables, including water availability. This tree frog species has a larval period of 15 days.