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The UK Bird Atlas

Bonaparte's Gull (Chroicocephalus philadelphia)Where and when to see it in the UK

Status not yet classified · reporting peaks July · Skimmers, Noddies, Terns, and Gulls · BOU category A

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

Bonaparte's Gull (Chroicocephalus philadelphia)
David Menke, Public domain, via Wikimedia Commons
Peak months
Bonaparte's Gull: 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.

Bonaparte's Gull has been recorded in 108 of the 2,971 10 km squares covering UK land (4%) in records to 2026. Its strongest squares are in England, Scotland and Wales. Reporting peaks in 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
100% or more of visits
High
4% to 100%
Moderate
<1% to 4%
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 11%<1%Low
February 5%<1%Very high
March 13%<1%Very high
April 52%<1%Moderate
May 21%<1%Low
June 21%<1%Very high
July 100%<1%Very high
August 63%<1%Moderate
September 9%<1%Moderate
October 4%<1%Moderate
November 7%<1%High
December 6%<1%High

Squares with the highest reporting rate in July

SquareWhereShare of visitsClass
NH19Highland, Scotland100%Very high
NM62Argyll and Bute, Scotland100%Very high
NM73Argyll and Bute, Scotland100%Very high
SD45Lancashire, England100%Very high
SZ08Dorset, England100%Very high
TR05Kent, England100%Very high
TR06Kent, England54%High
SD35Lancashire, England15%High
NR89Argyll and Bute, Scotland13%High
NT39Fife, Scotland5%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.