Alien mammalian species in Russia: ancient and modern invasions

There are about 70 alien species of mammals in Russia. Some species had occupied wide ranges before the 19th century, but most ones have penetrated into the new areas in the 20th century. Ancient invasions (before the 19th century) are known for rodents of human settlements (Mus musculus, Rattus rattus, Rattus norvegicus) and arable lands (Microtus levis, Microtus arvalis). In the European part of Russia these rodents are now common animals that cause harm to humans. In some regions they are continuing to expanding their ranges. The modern invasions are usually caused by human activities, and to a lesser extent by climate change. About half of the modern invasions represents self-spreading, intentional introductions constitute 23%, 16% are reintroductions, and 13% are accidental introductions. In the second half of the 20th century intentionally introduced mammals: (Neovison vison, Ondatra zibethicus, Nyctereutes procyonoides) occupied the largest areas. Among the self-spreading mammals, the greatest enlargements in geographical range were by Sus scrofa, Martes foina, and Pipistrellus kuhlii. These species have high reproductive potential and the ability to make long-distance movements. The distributions of invading mammals in Russian territory in the second half of the 20th century are illustrated in maps.