Mediterranean tree frog (Hyla meridionalis)

Also known as: stripeless tree frog
Synonyms: Hyla africana, Hyla arborea meridionalis, Hyla arborea var. meridionalis, Hyla barytonus, Hyla perezii, Hyla viridis var. meridionalis
  
French: Rainette Meridionale, Rainette Verte
Spanish: Ranita Meridional
KingdomAnimalia
PhylumChordata
ClassAmphibia
OrderAnura
FamilyHylidae
GenusHyla (1)
SizeLength: up to 6.5 cm (2)

The Mediterranean tree frog is classified as Least Concern (LC) on the IUCN Red List (1).

The Mediterranean tree frog (Hyla meridionalis) is a slender, smooth-skinned amphibian, with long limbs and adhesive discs on the digits which make it proficient at leaping and climbing (2) (3) (4). The discs of the forefeet are larger than those of the hindfeet (2) (3), and there is less webbing between the fingers than the toes (3).

The body of the Mediterranean tree frog is usually a vivid or bluish green, but it can also vary from yellowish to grey or brown, or may be spotted. The underparts are whitish (2) (3). There is a dark stripe running from the nostril, across the eye to the shoulder (2) (3). The eyes are brownish gold, with a horizontal pupil (2) (3) (4).

This species’ head is broader than it is long, and the snout is short and rounded (2) (3). Male Mediterranean tree frogs have a large vocal sac, which is dark yellow to brownish and is folded at rest, appearing rough in texture. In females, the throat region is somewhat lighter than the underparts (2) (3), while in juveniles the dark stripe along the side often extends further along the body (3). Mediterranean tree frog tadpoles are olive in colour, with golden stipples and spots and whitish underparts, and have a high, pointed tail fin and a dorsal fin which begins behind the eyes (3).

The Mediterranean tree frog is similar in appearance to the common tree frog (Hyla arborea), and the two species sometimes interbreed to form sterile hybrids (1) (5).  However, this species is more slender than the common tree frog and often has a more bluish tinge. In addition, the dark stripe ends at the shoulders rather than extending onto the body, giving the Mediterranean tree frog its alternative name of ‘stripeless tree frog’ (3).

As its common name suggests, the Mediterranean tree frog occurs in the Mediterranean region, where it is found in southern France, Spain, Portugal, northwest Italy, Monaco, Gibraltar, and in northern Africa in Morocco, northern Algeria and northern Tunisia (1) (2) (3) (5) (6). It has also been introduced in the Canary Islands, Madeira and Menorca (1) (2) (3) (5).

In the drier parts of its range, such as in parts of North Africa and the Iberian Peninsula, the distribution of the Mediterranean tree frog is more fragmented as less suitable habitat is available (1).

The Mediterranean tree frog can be found in trees, bushes and grass, usually near to fresh water (1) (3). It also occurs in orchards and vineyards (1), and has been found in holes in stone walls, cavities in the soil and even in concrete tubes (3). Breeding takes place in ponds, ditches, temporary pools, springs, lagoons, flooded meadows, wells and even swimming pools (1) (5).

Although usually found at low altitudes, the Mediterranean tree frog has been recorded up to elevations of 2,650 metres in Morocco (1) (2) (3).

The male Mediterranean tree frog calls from trees as well as from water and land, producing a loud, deep ‘cra-a-ar’ (2). The resonant calls can be heard some distance away, particularly when calling activity peaks during the breeding season, and many males calling together may produce a deafening chorus (2) (3). The timing of breeding varies with location, but is usually between March and April in North Africa, from April to June in France, from December to January in Portugal, and from about March in the Basque Country, Spain (2) (3) (7).

The Mediterranean tree frog lays between 800 and 1,000 eggs, in clumps of around 10 to 30. The female usually attaches the eggs to aquatic vegetation near the shore, where they are fertilised by the male, and the frogs leave the water after breeding, moving away into nearby trees (2) (3). The eggs of this species are yellowish and hatch after eight to ten days. The tadpoles measure just 5 to 8 millimetres on hatching, and grow to a total length of about 55 millimetres, with metamorphosis occurring around three to four months after the tadpoles hatch (2) (3).

The diet of the Mediterranean tree frog consists of a variety of invertebrates, including beetles, butterflies, moths, flies, ants and spiders (2) (3). This species may be active by both day and night (3), but it may hibernate during the winter months in some areas (7), while in others it becomes inactive (aestivates) in the summer (3).

The Mediterranean tree frog is a widespread and generally common species, and is not currently considered at risk of extinction (1). However, it faces a number of localised threats. For example, isolated populations in the Basque Country, Spain, are declining due to habitat loss and predation by introduced fish and crayfish species (1) (7), while populations in south-eastern Spain and in Italy are also in decline (1) (2).

The main threat to the Mediterranean tree frog is the loss of its habitat through development and agricultural intensification, and in particular the loss and pollution of freshwater breeding sites and the removal of waterside vegetation (1) (2) (5). Along the Mediterranean coast, this species may also be affected by an intensive anti-mosquito campaign (1) (2).

In addition to occurring in many protected areas throughout its range (1), the Mediterranean tree frog is protected in Europe under Appendix II of the Bern Convention (8) and Annex IV of the EU Habitats Directive (9). It is listed as Near Threatened in the Spanish Red Book (5) and is also listed on a number of other national Red Data Books and Lists, as well as being protected by national and local legislation (1).

Recommended conservation measures for the Mediterranean tree frog include more research into its biology, populations, genetics and susceptibility to pollution, as well as taking further measures to protect it in the areas in which the species is most vulnerable (5).

Find out more about the Mediterranean tree frog and other amphibian species:

Find out more about amphibian conservation:

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

  1. IUCN Red List (February, 2011)
    http://www.iucnredlist.org/
  2. AmphibiaWeb:
    http://www.amphibiaweb.org/
  3. Schleich, H.H., Kästle, W. and Kabisch, K. (1995) Amphibians and Reptiles of North Africa. Koeltz Scientific Books, Koenigstein, Germany.
  4. Halliday, T. and Adler, K. (2002) The New Encyclopedia of Reptiles and Amphibians. Oxford University Press, Oxford.
  5. Tejedo, M. and Reques, R. (2002) Hyla meridionalis (Boettger, 1874). Ranita meridional. In: Pleguezuelos, J.M., Márquez, R. and Lizana, M. (Eds.) Atlas y Libro Rojo de los Anfibios y Reptiles de España. Dirrección General de Conservación de la Naturaleza - Asociación Herpetologica Española, Madrid. Available at: 
    http://www.marm.es/es/biodiversidad/publicaciones/
  6. Frost, D.R. (2011) Amphibian Species of the World: An Online Reference. American Museum of Natural History, New York. Available at:
    http://research.amnh.org/vz/herpetology/amphibia/
  7. Etxezarreta, J. and Rubio, X. (1998) Notas sobre la biología reproductora y situación actual de la ranita meridional (Hyla meridionalis, Boettger, 1874) en el País Vasco. Munibe, 50: 77-83.
  8. Council of Europe: Bern Convention (February, 2011)
    http://conventions.coe.int/Treaty/EN/Treaties/Html/104.htm
  9. EC Habitats Directive (February, 2011)
    http://www.jncc.gov.uk/page-1374