Seabirds such as spotted shags, sooty shearwaters and variable oystercatchers are commonly seen. Dippers, choughs, puffins, guillemots, razorbills, short-eared owls, Manx shearwaters, whimbrel and plovers are also common. Ducie is important for its colonies of Murphy's, herald and Kermadec petrels, and Christmas shearwaters. The wedge-tailed shearwater is the largest of the tropical shearwaters. Manx shearwaters are long-lived birds. Swansea is home to colonies of short-tailed shearwaters (muttonbirds) and little penguins. Diving species, most especially the shearwaters, are also vulnerable to gillnet fisheries. Some Manx shearwaters "Puffinus puffinus" do this same journey in reverse. Puffin is an Anglo-Norman word (Middle English "pophyn") for the cured carcasses of nestling shearwaters. "Puffinus" shearwaters come to islands and coastal cliffs only to breed. The island is home to the largest colony of shearwaters in the Mediterranean. Many of the shearwaters in the genus "Puffinus" and "Ardenna" are proficient divers. Traditionally, "Puffinus" has been grouped with the "Procellaria" and "Calonectris" shearwaters. It comprises about 20 small to medium-sized shearwaters.