Ynys Lannog

Ynys Lannog, more commonly known in modern English as Puffin Island, is a small, uninhabited island situated off the eastern extremity of Anglesey, Wales. Historically, it bore the English name Priestholm and Welsh names such as Ynys Glannog, with its current Welsh designation being Ynys Seiriol, referring to Saint Seiriol. The island holds a significant place in early Welsh religious history, marked by the establishment of a hermitage around the 6th century, attributed to Saint Seiriol himself. Later, the island became the site of a monastery, with remains of a 12th-century church still visible today.

Geography and Natural History

Geographically, Ynys Lannog is the ninth-largest island off the Welsh coast and marks the northeastern boundary of the Menai Strait. Its highest point reaches 192 feet (59 meters) above sea level, characterized by steep cliffs on all sides. The island spans an area of approximately 69 acres (0.28 km2) and is privately owned by the Baron Hill estate. In contemporary times, Ynys Lannog is recognized as a Special Protection Area (SPA) due to its rich and diverse wildlife. It is particularly noted for its large colony of great cormorants, representing over 10% of the national population, making it one of the most significant colonies in the British Isles. The island also provides nesting grounds for guillemot, razorbill, shag, and kittiwake. Historically, it was a major breeding site for Atlantic puffins, although their numbers were severely impacted by the introduction of brown rats. A conservation program initiated in the late 1990s appears to have successfully eradicated the rats, leading to a resurgence in the puffin population. The surrounding strong currents support abundant marine life, attracting grey seals and regular visits from bottlenose dolphins and harbour porpoises.

Historical and Ecclesiastical Significance

The island's religious heritage is deeply connected to Saint Seiriol, son of the 5th-century ruler Owain Ddantgwyn. Saint Seiriol, after governing an ecclesiastical settlement at Penmon, chose to establish a hermitage on Ynys Lannog in his later years, and his remains are believed to be interred there. The island also served as a refuge; King Cadwallon ap Cadfan of Gwynedd is recorded as having sought shelter there around 630 AD during an invasion. By the late 12th century, a monastery was active on the island, famously described by Gerald of Wales, who recounted a tale of a plague of mice devouring the monks' food during times of internal strife. The monastery's importance is further evidenced by two charters issued by Llywelyn the Great in 1221 and 1237, which confirmed the rights of the Canons Regular to the island along with the church and manor of Penmon on the mainland. The ecclesiastical ruins on the island include the remains of a 12th-century church, which has been granted a Grade I heritage listing. While the central tower and nave foundations are visible, sections of the chancel and south transept are now obscured by a 19th-century cottage. Much later, a disused telegraph station was constructed on the island's northeastern tip, and a shipwreck, the steamship The Pioneer, is identified as having run aground offshore in 1878.