Geograph - photograph every grid square

The Welsh name, Ynys Seiriol, refers to Saint Seiriol. The son of Owain Ddantgwyn, a 5th-century ruler of the Kingdom of Gwynedd who founded and governed a clas (ecclesiastical settlement) at Penmon on the Anglesey. In later life, he abandoned his responsibilities there to establish a hermitage on the nearby island, where his remains are thought to rest.
The island is a Special Protection Area, particularly because of its great cormorant colony of over 750 pairs, making it one of the largest colonies in the British Isles. It also has good numbers of guillemot, razorbill, shag and kittiwake nesting, and in recent years small numbers of common eider and black guillemot. The Atlantic puffins from which the island gets its modern English name bred in considerable numbers at one time, with up to 2000 pairs recorded. The brown rat was introduced accidentally to the island, probably in the late 19th century and reduced this population to a very few pairs. A programme of poisoning these rats started in 1998 by the Countryside Council for Wales appears to have eradicated them, and the Puffin population has shown an increase since that date. (Wikipedia Link )