Alpine Newt

The alpine newt is medium-sized and stocky. It reaches 7–12 cm (2.8–4.7 in) length in total, females measuring roughly 1–2 cm (0.39–0.79 in) longer than males, and a body weight of 1.4–6.4 g. The tail is compressed sideways and is half as long or slightly shorter than the rest of the body. During their life in water, both sexes develop a tail fin, and males a low (up to 2.5 mm), smooth-edged crest on their back. The cloaca of males swells during breeding season. The skin is smooth during the breeding season and granular outside it, and is velvety during the animal's land phase. The characteristic dark grey to bright blue of the back and sides is strongest during breeding season. This base colour may vary to greenish and is more drab and mottled in females. The belly and throat are orange and only occasionally have dark spots. Males have a white band with black spots and a light blue flash running along the flanks from the cheeks to the tail. During breeding season, their crest is white with regular dark spots. Juvenile efts, just after metamorphosis, resemble adult terrestrial females, but sometimes have a red or yellow line on the back. Very rarely, leucistic individuals have been observed. While these traits apply to the widespread nominate subspecies, I. a. alpestris, the other subspecies differ slightly. I. a. …

The alpine newt is native to continental Europe. It is relatively common over a large, more or less continuous range from northwestern France to the Carpathians in Romania, and from southern Denmark in the north to the Alps and France just north of the Mediterranean in the south, but absent from the Pannonian Basin. Isolated areas of distribution in Spain, Italy and Greece correspond to distinct subspecies (see section Taxonomy: Subspecies above). Alpine newts have been deliberately introduced to parts of continental Europe, including within the boundaries of cities such as Bremen and Berlin. Other introductions have occurred to Great Britain, mainly England but also Scotland, and Coromandel Peninsula in New Zealand. A thriving introduced population was discovered in 2014 in the Catalonian Pre-Pyrenees (Santa Maria de Besora, Barcelona), likely established from released captive individuals; this population was found to be a carrier of ranavirus. The alpine newt can occur at high elevation and has been found up to 2,370 m (7,780 ft) above sea level in the Alps. It also occurs in the lowlands down to sea level. Towards the south of its range, most populations are found above 1,000 m (3,300 ft).

Alpine newts are usually semiaquatic, spending most of the year (9–10 months) on land and only returning to the water for breeding. The efts are probably terrestrial until they reach sexual maturity. At lower altitudes this occurs in males after around three years, and in females after four to five years. Lowland alpine newts can reach the age of ten. At higher altitudes, maturity is reached only after 9–11 years, and the newts can live for up to 30 years.

Terrestrial phase. On land, alpine newts are mainly nocturnal, hiding for most of the day and moving and feeding during the night or in the twilight. Hibernation also usually takes place in terrestrial hiding places. They have been observed to climb up to 2 metres (6.6 ft) on vertical walls of basement ducts, where they hibernated, on wet nights. Migration to breeding sites occurs on sufficiently warm (above 5 °C) and humid nights and may be delayed or interrupted for several weeks in unfavourable conditions. The newts can also leave the water in case of a sudden cold snap. Alpine newts tend to stay close to their breeding sites and only a small proportion, mainly juvenile efts, disperse to new habitats. A dispersal distance of 4 km (2.5 mi) has been observed, but such large distances are uncommon. …