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The UK Bird Atlas

Arctic Warbler (Phylloscopus borealis)Where and when to see it in the UK

Passage migrant · reporting peaks October · Leaf Warblers · BOU category A

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

Arctic Warbler (Phylloscopus borealis)
Arctic_Warbler_4683.jpg: Alnus derivative work: Osado, CC BY-SA 3.0, via Wikimedia Commons
Peak months
Arctic Warbler: 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.

Arctic Warbler has been recorded in 45 of the 2,971 10 km squares covering UK land (2%) in records to 2026. Passage migrant in the UK. Its strongest squares are in Scotland and England. Reporting peaks in October.

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
5% or more of visits
High
1% to 5%
Moderate
<1% to 1%
Low
under <1%
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 0%<1%Insufficient records
February 0%<1%Insufficient records
March 0%<1%Insufficient records
April 0%<1%Insufficient records
May 0%<1%Insufficient records
June 0%<1%Insufficient records
July 0%<1%Very high
August 10%<1%Low
September 78%<1%Low
October 100%<1%Moderate
November 3%<1%Low
December 0%<1%Insufficient records

Squares with the highest reporting rate in October

SquareWhereShare of visitsClass
HU34Shetland Islands, Scotland100%Very high
HU42Shetland Islands, Scotland100%Very high
HU43Shetland Islands, Scotland100%Very high
HU59Shetland Islands, Scotland100%Very high
NZ53Hartlepool, England14%Very high
NZ91North Yorkshire, England6%Very high
TA40Lincolnshire, England5%Very high
NU14Northumberland, England4%High
HU46Shetland Islands, Scotland3%High
TA41East Riding of Yorkshire, England3%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.