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The UK Bird Atlas

Black Guillemot (Cepphus grylle)Where and when to see it in the UK

Resident · reporting peaks June to July · Auks, Puffins, and Murres · BOU category AF

Records to 2026-08-16 · build 2026-08-31

Black Guillemot (Cepphus grylle)
No machine-readable author provided. Kelson assumed (based on copyright claims)., Public domain, via Wikimedia Commons
Peak months
Black Guillemot: relative reporting rate by 10 km square, September

Contains OS data © Crown copyright and database right 2026 (grid squares, place names from OS Open Names). Northern Ireland place names: OSNI Open Data, OGL v3.0. County and country boundaries: Office for National Statistics, Open Government Licence v3.0. Coastline: Natural Earth. Bird records from the data partners listed here.

Black Guillemot has been recorded in 745 of the 2,971 10 km squares covering UK land (25%) in records to 2026. Resident in the UK. Its strongest squares are in Scotland, Northern Ireland and England. Reporting peaks in June to July.

Conservation status: Least Concern (IUCN Red List, LC)
View on the IUCN Red List
Relative to this species' best squares (how classes are calculated)
Very high
39% or more of visits
High
17% to 39%
Moderate
6% to 17%
Low
under 6%
Surveyed, not recorded
at least 20 qualifying visits, no record
Insufficient records
too few visits to say
Lighter fill
Few visits, lower confidence
Small dot
Occasional: a single record, or out of season

Seasonality

Reporting rate by month, relative to the peak month
MonthRelative to peakShare of visitsTypical class
January 20%<1%Very high
February 30%<1%Very high
March 33%<1%Very high
April 38%<1%Very high
May 73%2%Very high
June 100%3%Very high
July 87%2%Very high
August 52%1%Very high
September 40%1%Very high
October 48%1%Low
November 23%<1%Very high
December 20%<1%Very high

Squares with the highest reporting rate in June

SquareWhereShare of visitsClass
D22Causeway Coast and Glens, Northern Ireland100%Very high
D30Mid and East Antrim, Northern Ireland100%Very high
D41Sea, off Mid and East Antrim100%Very high
HU53Shetland Islands, Scotland100%Very high
HU55Shetland Islands, Scotland100%Very high
HY33Orkney Islands, Scotland100%Very high
HY35Orkney Islands, Scotland100%Very high
HY52Orkney Islands, Scotland100%Very high
HY61Sea, off Orkney Islands100%Very high
HY73Orkney Islands, Scotland100%Very high

Spotted an error in a square? Report it and it goes into the review queue. Read the methodology for how classes, flags and sensitive-species rules work. Data to 2026.