First-winter Glaucous-winged Gull (Larus glaucescens) wintering in harbour of Hokkaido, Japan. Standing on the pier Stock Photo - Alamy
The rise and fall of Ring-billed Gull - BirdGuides
ID Guide to gulls – British Naturalists' Association
Great black-backed gull - Wikipedia
Herring Gull | NatureSpot
Seabirds | North Wales Wildlife Trust
Ring-billed gull - Wikipedia
Iceland Gull | Audubon Field Guide
Black-Headed Gull | Bird Spot
Common Gull Facts | Larus Canus - The RSPB
Common Gull Facts | Larus Canus - The RSPB
The secret life of seagulls - Wales' urban gulls spend their winters in Spain and Morocco - Wales Online
Herring Gull Bird Facts | Larus Argentatus - The RSPB
European herring gull - Wikipedia
Identification Guide to Winter Gulls - Part 1 - WingSearch2020
The rise and fall of Ring-billed Gull - BirdGuides
The rise and fall of Ring-billed Gull - BirdGuides
Species of the day: Herring Gull | Sussex Wildlife Trust
Do Seagulls Migrate? (All You Need To Know) | Birdfact
Herring Gull Bird Facts | Larus Argentatus - The RSPB
Gulls allowed? | BTO - British Trust for Ornithology
Identification Guide to Winter Gulls - Part 2 - WingSearch2020
