It is estimated that Switzerland is home to over 50,000 species of plants and animals – although only 83 of these are mammals, most of them bats and other small species. Thirty thousand of them are insects.

The number of animal species (mammals, birds, reptiles, amphibians and fish) remained more or less constant between 1997 and 2005; some have disappeared but others have become established or re-established. In some cases the new species have arrived of their own accord, while in others they were reintroduced.

There have been considerable fluctuations in the diversity of species in the past. It is thought that species diversity reached its highest point in the middle or end of the 19th century.

Switzerland signed the non-binding UN convention on biodiversity in 1994. This aims to reverse the world-wide decline in the number of different species of animals, plants and other organisms.