Mediterranean Tree Frog (Hyla meridionalis)
Order Anura, Family Hylidae, Genus Hyla, Species H. meridionalis
Species
Mediterranean Tree Frog (Hyla meridionalis)
Family
Order Anura, Family Hylidae, Genus Hyla, Species H. meridionalis
Size
Adults typically range from 40 to 65 millimeters in snout-to-vent length (SVL), with females generally being slightly larger and more robust than males. They possess extremely slender digits and long hind limbs, allowing them to make impressive leaps relative to their small body mass.
Conservation
Assessed as Least Concern by the IUCN Red List due to its wide distribution, tolerance of altered habitats, and generally stable populations. Localized threats include habitat destruction, pollution of breeding ponds, and introduced predatory fish.
Description
The Mediterranean tree frog is an agile and charismatic climber, easily recognized by its vibrant green skin and sleek silhouette. Often found clinging to vertical glass panes or damp vegetation, this tiny amphibian is a master of camouflage and vertical scaling. Its bright presence near garden ponds and human habitations adds a lively acoustic and visual element to the Mediterranean evening landscape.
Key Features
Smooth bright green skin, prominent dark eye-stripe extending from the snout through the tympanum, distinct adhesive toe pads, and lack of heavy dorsal spotting.
Physical Description
The Mediterranean tree frog features a relatively slender body with long, slender legs adapted for climbing. The head is broad and blunt, with prominent, protruding eyes possessing horizontal pupils. Digital tips bear distinct, rounded adhesive toe pads that allow the animal to adhere to vertical glass and smooth surfaces. The tympanum is small but visible directly behind the eye. There is no prominent dorsal ridge.
Skin Texture & Coloration
The dorsal skin is remarkably smooth and moist, typically bright leaf green, though individuals can shift to olive, yellowish, or brownish tones depending on temperature and background. A distinctive dark streak extends from the nostril, passing through the eye and across the tympanum, sometimes reaching the shoulder. The ventral surface is granular and off-white or yellowish. No aposematic warning colors are present.
Distinguishing Features
Key identification markers include the dark eye-stripe running from the snout through the eye, well-developed adhesive toe pads, and the absence of any significant dark spots on the back which distinguishes it from the European tree frog (Hyla arborea). The vocal sac in males is large and spherical when inflated, positioned subgularly.
Habitat
This arboreal species is commonly found in Mediterranean scrublands, woodlands, agricultural areas, and suburban gardens, frequently near standing water bodies such as ponds, irrigation ditches, and slow-moving streams. They are often encountered on vertical vegetation, reeds, bushes, and occasionally on human-made structures like windows and walls.
Geographic Range
Native to southwestern Europe (including Portugal, Spain, southern France, and northern Italy), northwestern Africa (Morocco, Algeria, Tunisia), and several Mediterranean islands (such as Menorca and Madeira where they were likely introduced). They thrive in warm Mediterranean climates.
Behavior
Primarily nocturnal and crepuscular, spending daylight hours resting on vegetation or smooth vertical surfaces where their green coloration provides camouflage. Locomotion involves precise climbing and powerful jumping. When threatened, they may freeze, leap away rapidly into dense cover, or emit a quiet release call.
Diet & Feeding
Diet consists primarily of small flying and crawling invertebrates, including flies, mosquitoes, moths, beetles, and spiders. They use a sit-and-wait hunting strategy, utilizing their sticky, projectile tongues to capture prey with high accuracy.
Reproduction
Breeding occurs during spring in temporary or permanent shallow aquatic bodies, triggered by warm temperatures and rainfall. Males congregate to form vocal choruses, attracting females. Amplexus is axillary. Females deposit small clusters of eggs directly into the water, which adhere to submerged vegetation.
Vocalizations
The advertisement call of the male is a loud, repetitive, low-pitched, rasping quack or rattle, often described as sounding like a mechanical duck or a rhythmic 'ark-ark-ark'. Choruses can be heard from a considerable distance during warm spring nights.
Life Cycle
Eggs hatch into aquatic tadpoles within several days depending on water temperature. The larval stage lasts between two to three months, during which tadpoles graze on algae and detritus. Metamorphosis occurs in early summer, producing tiny froglets that reach sexual maturity by their second year. Maximum lifespan in the wild is roughly 5 to 7 years.
Conservation Status
Assessed as Least Concern by the IUCN Red List due to its wide distribution, tolerance of altered habitats, and generally stable populations. Localized threats include habitat destruction, pollution of breeding ponds, and introduced predatory fish.
Toxicity & Defense
Non-toxic to humans. Skin secretions are mild and generally only cause irritation if they come into contact with mucous membranes. Primary defenses rely on crypsis, rapid jumping, and climbing out of reach of predators.
Ecological Role
Acts as an important predator of flying insects and mosquitoes, helping to regulate local arthropod populations. Serves as prey for birds, snakes, and carnivorous mammals, functioning as a vital link in the local food web.
Similar Species
Frequently confused with the European Tree Frog (Hyla arborea). Hyla meridionalis typically lacks the prominent lateral spots and dark flanks found in H. arborea, and its call has a lower pitch and slower repetition rate.
Observation Tips
Best observed at night during spring and summer using a flashlight near garden ponds, irrigation channels, or smooth vertical walls where garden lights attract their insect prey. Listening for their characteristic rattling calls is the easiest way to locate them.
Handling & Safety
Harmless to humans, though amphibians should generally not be handled unless necessary. If handling is required, hands must be clean, wet, and free of chemical residues, lotions, or insect repellents to protect the frog's sensitive permeable skin.
Seasonal Activity
Active from early spring through autumn. During the colder winter months, they undergo brumation, burying themselves in loose soil, leaf litter, or crevices near the ground until temperatures rise again in spring.
Cultural Significance
Represented in local folklore as harbingers of rain and warm weather due to their vocal activity increasing prior to storms. They are popular subjects in regional nature photography and serve as friendly, familiar neighbors in Mediterranean gardens.
Interesting Facts
Mediterranean tree frogs possess the remarkable ability to adhere to vertical glass surfaces using specialized mucus and microscopic channels on their toe pads, a trait that frequently leads to them being spotted pressed against household windows at night.