The Great Britain
mammal fauna is somewhat impoverished compared to that of continental Europe due
to the short period of time between the last ice age and the flooding of the
land bridge between Great Britain and the rest of Europe. Only those land
species which crossed before the creation of the English Channel and those
introduced by humans exist in Great Britain.
Great Britain holds a small (Scottish) population of European Wildcats, important populations of Grey Seals, and rare bat species.
Native (usually synonymous with "indigenous") species are considered to be species which are today present in the region in question, and have been continuously present in that region since a certain period of time. When applied to Great Britain, three possible definitions of this time constraint are:
a species that colonised the islands during the glacial retreat at the end of the last ice age (c.9500 years ago);
a species that was present when the English Channel was created (c.8000 years ago);
or, a species that was present in Prehistory.
This list includes mammals from the small islands around Great Britain and the Channel Islands. There are no endemic mammal species in Great Britain, although four distinct subspecies of rodents arose on small islands.
I have included our Native British mammals and also some that have been introduced and re-introduced that are here to stay
Bats (more detailed information)