of scent released encourages the ruff sniff display. A ruff sniff display is when birds fully insert their half open bill into the other's plumage. This display occurs in the absence of obvious aggression and is important for pair formation. For both sexes, a strong odor attracts more individuals, which then do a ruff sniff display. Odor secretions increase during the breeding season, highlighting its association with courtship and mate selection. The scent may also act as an ectoparasite repellent. This scent is also found in whiskered auklet. Conservation status According to the International Union for Conservation of Nature, crested auklets are of least concern. The global population exceeds 8.2 million individuals, while the North American population is estimated at 2.9 million birds. However, an accurate assessment of the number of birds is difficult, since those on the surface of the colony and in the nearby sea form only a small proportion of the variable and poorly understood population. There is greater concern for the Alaskan population. There has been high predation by rats which have escaped from fishing vessels in the harbor. The auklets' main predators are gulls, Arctic fox and common ravens. They have also been reported in the stomachs of halibut caught on St. Lawrence Island. Oil spills and collisions with light sources pose additional risks. In Alaska, there is some subsistence hunting of the species. References Bibliography Books Alderfer, Jonathan; Dunn, Jon L (2011) Field Guide to the Birds of North America, (6th edition) National Geographic Society. Harrison, Peter (1983) Seabirds, an Identification Guide, Houghton Mifflin, del Hoyo, Josep (1996) Handbook of the Birds of the World: Hoatzin to Auks Vol 3, Lynx. Sibley, David Allen (2000) The Sibley Guide to Birds, National Audubon Society. Websites Aethia Auklets Birds of the Arctic Birds of the Aleutian Islands Birds described in 1769 Taxa named by Peter Simon Pallas