The Perez's frog (Pelophylax perezi), also known as Iberian waterfrog, Iberian green frog or Coruna frog, is a species of frog in the family Ranidae. It is native to southern France, Portugal, Spain, and has been introduced to the Canary and Balearic Islands, Madeira, the United Kingdom, and the Azores. In the Iberian Peninsula it is widespread and common.
Its natural habitats are temperate forests, temperate shrubland, Mediterranean-type shrubby vegetation, rivers, intermittent rivers, swamps, freshwater lakes, intermittent freshwater lakes, freshwater marshes, intermittent freshwater marshes, sandy shores, arable land, and urban areas.
It is a big (up to 10cm of total length) anura (amphibian without a tail in adult stage). It has a long and wide head, with a rounded snout and a very visible eardrum. The hind limbs are highly developed, adapted for diving and swimming, with large inter digital membranes. The skin is smooth or slightly grainy and the colour pattern can vary a lot, from greenish tones to brown. It usually presents a clear vertebral line (which divides the back longitudinally into two symmetrical parts). The larva reaches a large size at the end of its development (up to 7 cm of total length). The body is somewhat depressed and the tail has a small caudal ridge and ends in a tip. The dorsal colouration is brownish or greenish, with irregular dark spots. The ventral area is white.
This species can be found in practically any water point, although it prefers places where water is maintained during spring and summer, where its larvae develop. Its presence is independent of the environment surrounding the water point. It is the typical inhabitant of rivers and streams, as well as channels and irrigation pools.
It is the most aquatic amphibian, with both daytime and nocturnal habits. It usually sunbaths on wetlands shores, where it is very present. Although its presence becomes more noticeable during the mating period and the warmest months, it can be active all year long. Adult frogs feed on a wide variety of invertebrates (insects, spiders, earthworms, etc.), while tadpoles consume organic algae and debris.
The reproductive period generally ranges from March to July, although it may start in January or February depending on the rainfall that occurred during the year. Males sing night and day. The females lay bubbly masses of hundreds of eggs that remain attached to the aquatic vegetation or deposits in the wetland bed. A week later, the larvae hatch and develop for about three months until the metamorphosis occurs. Baby frogs (2 to 3.5 cm long) lose their gills and acquire lungs. Most of the little frogs appear in summer, although some larvae can spend winter in permanent water points with abundant food, to reach larger sizes and delay the metamorphosis to the following year. That is why it is not difficult to observe this species’ larvae throughout the year.