Examples include albatross, penguins, gannets, and auks. Avifauna species number 200, including auks, tufted puffins and swans. Skuas and jaegers are related to gulls, shorebirds, auks, and skimmers. Skuas are related to gulls, waders, auks, and skimmers. The family Alcidae includes auks, murres, and puffins. Waders are members of the order Charadriiformes, which includes gulls, auks and their allies. The last colony of great auks lived on Geirfuglasker (the "Great Auk Rock") off Iceland. Diving birds also use diving locomotion (e.g., dippers, auks). These birds forage for food like other auks by swimming underwater. Up to 500 whole auks are packed into the seal skin, beaks and feathers included. It nests in colonies, often with other auks. Biodiversity of auks seems to have been markedly higher during the Pliocene. The sailors then herded hundreds of great auks onto the ships, where they were slaughtered. Collection of great auks for museums pushed the already rare species to extinction.