The Cretan frog (Pelophylax cretensis) is a species of frog in the family Ranidae. It is endemic to the Greek island of Crete.[1]
It is a medium-sized frog reaching up to 8 cm in length and with a weight of 40g.[2] The Cretan frog is generally light grey to brown and mottled with brown or olive-grey spots on its back, while the throat and underside of the body are whitish-grey. Occasionally, the upperparts of the Cretan frog may be grass-green with distinct brown spots. The insides of the hind legs are yellow, and the sides of the body may also have yellowish colouration. This species has a prominent dark brown fold of skin down the back.[3] Its skin is smooth and slightly glossy. Males may feature prominent vocal sacs on their throats, especially during breeding season. Its long, muscular hind legs, common to frogs, are a key aspect of their agile swimming and jumping abilities.[4]
It is a generally diurnal, shy frog that usually basks out of water and will jump into the water when it feels threatened. Nocturnal behaviors have also been reported, with individuals in some areas being predominantly active after sunset. It is typically solitary in nature and communicates via a sequence of distinct calls. Its lifespan is six to eight years in the wild.
It mates in spring and females lay their eggs in the water in clusters of a few hundred. Every female frog can lay up to 5000 eggs and they hatch after about a week,[5] depending on water temperature.[6] During breeding season, males develop prominent vocal sacs on their throats and they aggressively defend their territories, employing a variety of strategical calling and physical confrontation.
Cretan frogs predominantly consume invertebrates, with a food preference leaning towards aquatic insects, snails, and small crustaceans. They are opportunistic feeders, eying for readily available prey.
It is endemic to the Greek island of Crete, where it is found across most of the island except of the very mountainous mainland. It rarely inhabits areas of an elevation of more than 100 meters.Its natural habitats are Mediterranean-type shrubby vegetation, rivers, intermittent rivers, swamps, freshwater lakes, intermittent freshwater lakes, freshwater marshes, intermittent freshwater marshes, and plantations.
The Cretan frog is listed as a Vulnerable species in the IUCN Red List of Threatened Species, and its population is declining.
A huge number of Cretan frogs once inhabited Lake Agia (Ayia), one of the only two freshwater lakes in Crete. However, this population has dangerously decreased since the introduction of the American Bullfrog to the lake. The American Bullfrog, which is endemic to California, was brought to the area in order to be bred in captivity for the production of frog legs. In 2000, a businessman from Chania who bred bullfrogs was disappointed by his investment and released all of his frogs into the Lake Agia. The American Bullfrog is four times bigger than the Cretan frog and a lot more aggressive, as a result it is outcompeting the local population of frogs. This has resulted in an almost complete displacement of the Cretan frogs from the lake. The biggest problem is that Lake Agia does not host a natural enemy so to stop this invasive species rapid spread.
The habitat of the Cretan frog in other areas is also under severe threat, being of poor quality, extremely fragmented and decreasing in size, mainly due to new developments for the tourism industry as well as other infrastructure development. Water is also being extracted for agriculture, drying out water bodies and leaving the frogs without the necessary means to eat, reproduce or live.
Although this species inhabits a number of protected areas, some of these are not currently well managed or protected correctly for conserving species and as a result greater actions should be taken in order for the Cretan frog's population to recover.