The razorbill, razor-billed auk,[4] or lesser auk[5] (Alca torda) is a North Atlantic colonial seabird and the only extant member of the genusAlca of the family Alcidae, the auks. It is the closest living relative of the extinct great auk (Pinguinus impennis).[6]
Razorbills are primarily black with a white underside. The male and female are identical in plumage; however, males are generally larger than females. This agile bird, which is capable of both flight and diving, has a predominantly aquatic lifestyle and only comes to land in order to breed. It is monogamous, choosing one partner for life. Females lay one egg per year. Razorbills nest along coastal cliffs in enclosed or slightly exposed crevices. The parents spend equal amounts of time incubating, and once the chick has hatched, they take turns foraging for their young.
In 1918, the razorbill was protected in the United States by the Migratory Bird Treaty Act. Presently, this species faces major threats, including the destruction of breeding sites,[7] oil spills,[8] and deterioration of food quality. The IUCN records the population of the species as fluctuating,[1] causing its status to interchange. It has been recorded that the population had increased from 2008 to 2015,[9] decreased from 2015 to 2021,[10] and appears to be increasing or stable at the present.[1] It is estimated that the current global razorbill population lies between 838,000 to 1,600,000 individuals.[1]
^Proceedings of the Society of Antiquaries of Scotland, Volume 13 (Edinburgh: Society of Antiquaries of Scotland, 1879), ISBN9781248434567
^Moum, Truls; Arnason, Ulfur; Árnason, Einar (2002). "Mitochondrial DNA sequence evolution and phylogeny of the Atlantic Alcidae, including the extinct Great Auk (Pinguinus impennis)". Molecular Biology and Evolution. 19 (9). Oxford: Oxford University Press: 1434–1439. doi:10.1093/oxfordjournals.molbev.a004206. PMID12200471.