Much of Anglesey is used for relatively intensive cattle and sheep farming. However, there are several important wetland sites that have protected status. In addition, the several lakes all have significant ecological interest, including their support for a wide range of aquatic and semi-aquatic bird species. In the west, the Malltraeth Marshes are believed to support an occasional visiting bittern, and the nearby estuary of the Afon Cefni supports a bird population made internationally famous by the paintings of Charles Tunnicliffe, who lived for many years and died at Malltraeth on the Cefni estuary. The RAF airstrip at Mona is a nesting site for skylarks. The sheer cliff faces at South Stack near Holyhead provide nesting sites for huge numbers of auks, including puffins, razorbills and guillemots, together with choughs and peregrine falcons. Anglesey is home to several species of tern, including the roseate tern. Three sites on Anglesey are important for breeding terns – see Anglesey tern colonies. There are marked occurrences of the "Juncus subnodulosus"–"Cirsium palustre" fen-meadow plant association, a habitat marked by certain hydrophilic grasses, sedges and forbs. Anglesey supports two of the UK's few remaining colonies of red squirrels, at Pentraeth and Newborough. Almost the entire coastline of Anglesey is designated as an Area of Outstanding Natural Beauty (AONB) to protect the aesthetic appeal and variety of the island's coastal landscape and habitats from inappropriate development. The coastal zone of Anglesey was designated as an AONB in 1966 and confirmed as such in 1967. The AONB is predominantly a coastal designation, covering most of Anglesey's coastline but also encompasses Holyhead Mountain and Mynydd Bodafon. Substantial areas of other land protected by the AONB form the backdrop to the coast. The AONB is about 221 km2 (85 sq mi) and it is the largest AONB in Wales, covering one third of the island. A number of the habitats in Anglesey gain still greater protection through both UK and European designations of their nature conservation value. These include: These habitats support a variety of wildlife, such as harbour porpoises and marsh fritillary. The AONB also takes in three sections of open, undeveloped coastline designated as Heritage Coast.