Lichens are formed by a symbiotic association of a fungus and an alga and are very susceptible to atmospheric pollution. Alderney's unpolluted atmosphere has helped to retain a number of species in this group which are generally declining in the U.K. 30 species of Liverworts and 145 Mosses have been found in the island. The most common wild animal. Possibly introduced by the Romans or the Monks of the 8-9th centuries. The inhabitants also fell into conflict with the Seigneur over the damage done by rabbits spreading from his warren the Mannez Garenne , still marked on maps today, and were given permission by the Crown to take or kill any found outside its boundaries and remove their droppings.
Numbers now fluctuate from year to year with myxomatosis.
A number of black rabbits will be seen, the lack of natural predators ensuring their survival despite being more conspicuous. Hedgehogs Next in size and frequency of sighting is the hedgehog. They are almost certainly introduced, probably since the 1939-45 war, probably in the early 1960s. They have thrived, with no natural predators and amongst them are considerable numbers of a pale blond species, with dark eyes and light brown nose and feet, uncommon elsewhere and in almost equal numbers to the more usual brown variety. Rarely, albino specimens are seen with pink eyes, nose and feet.