Editing Razorbill (section)

{{Use dmy dates|date=August 2023}}
{{Short description|Species of auk}}
{{Other uses}}
{{Speciesbox
| image = Razorbill with a nice catch.jpg
| image_caption = On [[Stora Karlsö]], [[Gotland]], Sweden [[File:Razorbill (Alca torda) (W1CDR0001424 BD7).ogg|thumb|center|Pair of Razorbills calling, recorded on [[Skokholm]], Wales]]
| status = LC
| status_system = IUCN3.1
| status_ref = <ref name="IUCN (Global)">{{cite iucn |author=BirdLife International. |year=2021 |errata=2023 |title=''Alca torda'' |volume=2021 |page=e.T22694852A228697220 |doi=10.2305/IUCN.UK.2021-3.RLTS.T22694852A228697220.en |access-date=18 April 2024}}</ref> (Global)
| status2 = LC
| status2_system = IUCN3.1
| status2_ref = <ref name="IUCN (Europe)">{{cite iucn |author=BirdLife International. |year=2021 |title=''Alca torda'' (Europe assessment) |volume=2021 |page=e.T22694852A166289520 |doi=10.2305/IUCN.UK.2021-3.RLTS.T22694852A166289520.en |access-date=18 April 2024}}</ref> (Europe)
| genus = Alca
| parent_authority = 
| species = torda
| authority = [[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]]
| subdivision_ranks = Subspecies
| subdivision_ref = <ref>Gill F, D Donsker & P Rasmussen (Eds). 2020. IOC World Bird List (v10.2). doi : 10.14344/IOC.ML.10.2.</ref>
| subdivision =
* ''A. t. torda'' - Linnaeus, 1758
* ''A. t. islandica'' - Brehm, CL, 1831
| range_map = Alca torda map.svg
}}

The '''razorbill''' ('''''Alca torda''''') is a North Atlantic colonial [[seabird]] and the only extant member of the [[genus]] ''[[Alca (bird)|Alca]]'' of the family [[Alcidae]], the [[auk]]s. It is the closest living relative of the extinct [[great auk]] (''Pinguinus impennis'').<ref name="Moum">{{cite journal |last=Moum |first=Truls |author2=Arnason, Ulfur |author3=Árnason, Einar |title=Mitochondrial DNA sequence evolution and phylogeny of the Atlantic Alcidae, including the extinct Great Auk (''Pinguinus impennis'') |journal=Molecular Biology and Evolution |volume=19 |issue=9 |pages=1434–1439 |year=2002 |publisher=[[Oxford University Press]] |location=Oxford |pmid=12200471 |doi=10.1093/oxfordjournals.molbev.a004206}}</ref> Historically, it has also been known as "auk",<ref name=Lockwood>{{cite book | last=Lockwood | first=William Burley  | author-link=William Burley Lockwood | date=1984 | title=The Oxford Dictionary of British Bird Names | location=Oxford | publisher=Oxford University Press | isbn=0-19-214155-4 }}</ref> "razor-billed auk"<ref name=AOU1931>{{Citation| author = American Ornithologists' Union | title = A Check-List of North American Birds | place = Lancaster, PA | publisher = Lancaster Press | year = 1931 | edition = 4th | page = 144 | language = English | url = https://archive.org/details/checklistofnorth1931amer/page/144/mode/2up }}</ref> and "lesser auk".<ref>''Proceedings of the Society of Antiquaries of Scotland, Volume 13'' (Edinburgh: Society of Antiquaries of Scotland, 1879), {{ISBN|9781248434567}}</ref>

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 [[Monogamy in animals|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.

Presently, this species faces major threats, including the destruction of breeding sites,<ref>{{Cite journal |url=https://birdsna.org/Species-Account/bna/species/razorb/introduction |title=Razorbill - Introduction - Birds of North America Online |last1=Lavers |first1=Jennifer |last2=Hipfner |first2=J. Mark |last3=Chapdelaine |first3=Gilles |date=28 October 2009 |journal=Birds of the World |doi=10.2173/bow.razorb.01 |s2cid=216173366 |language=en |access-date=2018-09-06|url-access=subscription }}</ref> oil spills,<ref>{{cite web|url= https://www.researchgate.net/publication/228497510|title= The Tricolor oil spill: Characteristics of seabirds found oiled in the Netherlands|date= January 2004|volume= 6|last1= Leopold|first1= Mardik}}</ref> and deterioration of food quality. The IUCN records the population of the species as fluctuating,<ref name="IUCN (Global)"/> causing its status to interchange. It has been recorded that the population had increased from 2008 to 2015,<ref name="IUCN (Global) (2009)">{{Cite IUCN|title=''Alca torda'' (Razorbill)|author=BirdLife International|date=1 May 2009|page=e.T22694852A23088501|archive-date=19 August 2023|archive-url=https://web.archive.org/web/20230819055950/https://www.iucnredlist.org/species/22694852/23088501|access-date=18 April 2024}}</ref> decreased from 2015 to 2021,<ref name="IUCN (Global) (2015)">{{Cite IUCN|title=''Alca torda'' (Razorbill)|author=BirdLife International|date=1 October 2015|page=e.T22694852A82978388|doi=10.2305/IUCN.UK.2015-4.RLTS.T22694852A82978388.en|archive-url=https://archive.today/20240418172006/https://www.iucnredlist.org/species/22694852/82978388|archive-date=18 April 2024|access-date=18 April 2024}}</ref> and appears to be increasing or stable at the present.<ref name="IUCN (Global)"/> It is estimated that the current global razorbill population lies between 838,000 and 1,600,000 individuals.<ref name="IUCN (Global)"/> In 1918, the razorbill was protected in the United States by the [[Migratory Bird Treaty Act of 1918|Migratory Bird Treaty Act]].