Lemon-yellow tree frog (Hyla savignyi)
|Also known as:||Savigny’s tree frog|
|Size||Snout-vent length: 3 - 4.7 cm (2)|
- The colouration of the lemon-yellow tree frog can vary with temperature and with the substrate on which it lives.
- The male lemon-yellow tree frog can be distinguished from the female by the large vocal sac on its throat.
- The male lemon-yellow tree frog produces a call that sounds like the chirping of a cicada.
- The lemon-yellow tree frog is quite tolerant of heat, and is often found in hot, arid environments such as deserts.
The lemon-yellow tree frog is classified as Least Concern (LC) on the IUCN Red List (1).
The lemon-yellow tree frog (Hyla savignyi) is a medium-sized frog with long hind limbs and slight webbing between the digits on the feet (3). The tips of the digits are expanded into discs (2), which are smaller on the hind limbs than on the forelimbs (3). The back of the lemon-yellow tree frog is smooth, while the throat and underside have a rough texture (3).
As its common name suggests, the lemon-yellow tree frog is typically yellowish to light green (2), but variations of brown and straw colouration can also exist (3). Its overall colouration varies depending on factors such as the external temperature and the colour of the substrate that the frog lives on (2). The underside of the lemon-yellow tree frog is white, and a dark line extends along the side of the body from the nostrils to the hind legs (3).
The male and female lemon-yellow tree frog are very similar in appearance, but can be distinguished from one another by the large vocal sac that is visible externally on the male frog (2) (3), appearing as darker folds and wrinkles of skin on the throat (2).
The lemon-yellow tree frog was previously considered to be a subspecies of the common tree frog (Hyla arborea) (1) (4), but differs slightly in its colouration and in its calls (2) (4).
The lemon-yellow tree frog has a widespread distribution across western Asia and the Middle East, from Cyprus and Turkey, through Syria, Georgia, Armenia, Iraq and Azerbaijan to Iran (1) (2). It also occurs south into Israel and Jordan (1) (2), and in a small area in north-eastern Sinai, Egypt, near the border with Israel (1) (2) (3). An isolated population also occurs in the south-western Arabian Peninsula, in Saudi Arabia and Yemen (1) (2).
This frog has been recorded from elevations of 400 metres below sea level to over 1,800 metres above sea level (1).
Like other Hyla species, the lemon-yellow tree frog has a preference for warm climates (5), and this species is often found in hot, arid habitats such as deserts, semi-deserts and steppes (1) (2). The lemon-yellow tree frog is well adapted to hot environments and is quite tolerant to heat (2).
The lemon-yellow tree frog is also found in semi-urban areas, cultivated areas, gardens, montane forest edges, oases, and areas with permanent or semi-permanent water sources (1) (2) (3). Although it mainly occurs near water (2), the lemon-yellow tree frog is not always confined to wetlands and may also be seen at great distances from water in quite dry environments, such as on rocky slopes (1) (2) (3).
The lemon-yellow tree frog breeds in small, stagnant water bodies such as ponds and puddles, as well as in slow-flowing streams with dense vegetation (1) (2). This species usually has a preference for clear, shallow water with some surrounding vegetation (6).
Like other tree frogs of the Hyla genus, the lemon-yellow tree frog is semi-aquatic (5). Adult lemon-yellow tree frogs are often found sitting on trees and bushes, under logs or stones, or in burrows. This species becomes nocturnal after the breeding season, starting its foraging in the late evening and visiting water bodies to rehydrate (2). The adult frog’s diet consists mainly of insects such as beetles, flies and hymenopterans (wasps, bees and ants), and it may also take spiders and molluscs (2).
During the breeding season, the male lemon-yellow tree frog calls to the female with a call that resembles a chirping cicada. The female lemon-yellow tree frog can lay a clutch of around 200 to 1,000 eggs, depositing them in clumps in the water or upon the water vegetation. After the tadpoles hatch, they feed on various types of animal matter and plants. The tadpoles metamorphose into adults in the summer, and sexual maturity is thought to occur at the age of three to four (2).
The lemon-yellow tree frog hibernates during the months of October to April, but hibernation may be shorter or may not occur at all in southern parts of its range. Hibernation occurs on land, for example within burrows in the soil (2).
The lemon-yellow tree frog is widespread and able to survive in a wide range of habitats, and therefore is not currently considered to be at risk of extinction. It is often quite common in suitable habitat, and in Israel it is the most abundant amphibian species (1).
However, this species may face a number of localised threats. One of the main threats to the lemon-yellow tree frog is the fragmentation of its habitat, for example due to roads and to irrigation practices, which can dry up water bodies. The lemon-yellow tree frog is particularly sensitive to the fragmentation of its habitat as it has a low ability to migrate large distances, so may be prevented from dispersing (6). Further factors threatening this species’ habitat include drought and overgrazing by livestock (1).
Like most amphibians, the lemon-yellow tree frog is constrained by water quality, and can therefore be affected by the use of insecticides and pesticides. It may also be affected by other forms of water pollution (1) (6).
The need for wetlands in arid regions is an essential factor in the survival of tree frog populations, enabling them to rehydrate and reproduce (2). In Israel, these habitats have declined in recent years, leading to a decline in breeding sites for the lemon-yellow tree frog (1).
The lemon-yellow tree frog occurs in a number of protected areas in Turkey, Jordan, Georgia, Armenia, Lebanon and Azerbaijan. This species is additionally protected in Israel under national legislation (1).
No other specific conservation measures are currently known to be in place for this colourful amphibian.
Find out more about the lemon-yellow tree frog and other amphibians:
More information on amphibian conservation:
IUCN/SSC Amphibian Specialist Group:
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- Genus: a category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.
- Hibernation: a winter survival strategy in which the animal passes the winter in a resting state. This period of inactivity is characterised by specific biological and biochemical changes including lowered blood pressure and respiration rate.
- Metamorphosis: an abrupt physical change from the larval to the adult form.
- Molluscs: a diverse group of invertebrates, mainly marine, that have one or all of the following; a horny, toothed ribbon in the mouth (the radula), a shell covering the upper surface of the body, and a mantle or mantle cavity with a type of gill. Includes snails, slugs, shellfish, octopuses and squid.
- Montane forest: forest occurring in mountains.
- Nocturnal: active at night.
- Steppe: a vast grassland plain, characterised by few trees and low rainfall.
- Subspecies: a population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.
IUCN Red List (March, 2011)
AmphibiaWeb - Hyla savignyi (March, 2011)
- Baha El Din, S. (2006) A Guide to the Reptiles and Amphibians of Egypt. American University in Cairo Press, Cairo.
- Gvoždík, V., Moravec, J. and Kratochvíl, L. (2008) Geographic morphological variation in parapatric Western Palearctic tree frogs, Hyla arborea and Hyla savignyi: are related species similarly affected by climatic conditions? Biological Journal of the Linnean Society, 95: 539-556.
- Gvoždík, V., Moravec, J., Klütsch, C. and Kotlík, P. (2010) Phylogeography of the Middle Eastern tree frogs (Hyla, Hylidae, Amphibia) as inferred from nuclear and mitochondrial DNA variation, with a description of a new species. Molecular Phylogenetics and Evolution, 55: 1146-1166.
Klütsch, C.F.C. (2006) Evolutionary History of Southern Arabian Faunal Elements with a Special Focus on Habitat Fragmentation of Two Model Organisms, Reissita simonyi (Rebel, 1899; Lepidoptera: Zygaenidae) and Hyla savignyi (Audouin, 1827; Amphibia: Hylidae). PhD Thesis, Universität Bonn, Bonn. Available at: