The Scilly shrew is a white-toothed shrew and is not found on the British Mainland.
The Scilly shrew is now recognised as a subspecies of the lesser white-toothed shrew Crocidura suaveolens cassiterdum, which is also not a British mainland species.
Shrews are insectivores and their droppings look very much like bat droppings and this has misled many an ecologist. Shrews are harmless and nearly every Scillonian house has a resident shrew, most are welcome visitors and their antics enjoyed while they are looking for scraps of food to eat. They are famous for their habit of 'caravanning' where a mother moves her litter by having each holding onto the tail in front with their teeth so that none get lost.
No one knows when the Scilly shrew arrived to the islands but remains have been found in a Bronze Age Midden on St. Agnes, in Bronze Age levels on Nornour, and Roman/Early Medieval remains on Tean. The Scilly shrew may be a relict species present before Scilly became isolated from the continent, while others suggest that shrews were stowaways on boats coming from the Channel Islands and France.
Shrews are a protected species and can only be trapped for study under licence from Natural England.