function is unknown. When adult newts are in the presence of a predator, they tend to flee a majority of the time. However, the decision of whether or not to flee can depend on the newt’s sex and temperature. In an experiment, female newts fled more often and at a greater speed over a greater range of temperatures than males, who tended to flee at a slower speed and remained immobile while secreting tetrodotoxin when the temperature was outside of the normal range. Parasites include parasitic worms, leeches, the ciliate Balantidium elongatum, and potentially toadflies. A ranavirus transmitted to alpine newts from midwife toads in Spain caused bleeding and necrosis. The chytridiomycosis-causing fungus Batrachochytrium dendrobatidis has been found in wild populations, and the emerging B. salamandrivorans was lethal for alpine newts in laboratory experiments. Captivity Several subspecies of the alpine newt have been bred in captivity, including a population from Prokoško Lake in Bosnia that is now probably extinct in the wild. Efts often return to the water after only one year. Captive individuals have reached an age of 15–20 years. Threats and conservation Because of its overall large range and populations that are not severely fragmented, the alpine newt was classified as Least Concern on the IUCN Red List in 2009. The population trend, however, is "Decreasing", and the different geographic lineages, which may represent evolutionary significant units, have not been evaluated separately. Several populations in the Balkans, some of which have been described as subspecies of their own, are highly threatened or have even gone extinct. Threats are similar to those affecting other newts and include mainly destruction and pollution of aquatic habitats. Beavers, previously widespread in Europe, were probably important in maintaining breeding sites. Introduction of fish, especially salmonids such as trout, and potentially crayfish is a significant threat that can eradicate populations from a breeding site. In the Montenegrin karst region, populations have declined as ponds created for cattle and human use were abandoned over the last decades. Lack of adequate, undisturbed land habitat (see section Habitats above) and dispersal corridors around and between breeding sites, is another problem. Effects as introduced species Introduced alpine newts may pose a threat to native amphibians if they carry disease. A particular concern is chytridiomycosis, which was found in at least one introduced population in the United Kingdom. In New Zealand, the risk of spreading chytridiomycosis to endemic frogs