Gulls & Terns in Colorado
Our list for Colorado has 15 gulls & terns recorded regularly there: 2 summer visitors, 6 winter visitors and 7 passage migrants
Most likely in October
GBIF · OctShare of all bird records in Colorado in October, 2019–2024. Each month links to that month’s page.
All 15, most common first
Ring-billed GullLarus delawarensisWinter visitorCommon43–54 cmRegularly Jul–May
American Herring GullLarus smithsonianusWinter visitorUncommon53–65 cmRegularly Sep–Apr
Franklin's GullLeucophaeus pipixcanPassage migrantUncommon32–36 cmRegularly Mar–Nov
Bonaparte's GullChroicocephalus philadelphiaPassage migrantUncommon28–38 cmRegularly Oct–May
Lesser Black-backed GullLarus fuscusWinter visitorUncommon52–64 cmRegularly Sep–Apr
Sabine's GullXema sabiniPassage migrantUncommon27–33 cmRegularly Aug–Oct
Forster's TernSterna forsteriSummer visitorUncommon33–36 cmRegularly Apr–Oct
Iceland GullLarus glaucoidesWinter visitorUncommon52–60 cmRegularly Oct–Apr
Black TernChlidonias nigerSummer visitorUncommon22–26 cmRegularly May–Sep
Great Black-backed GullLarus marinusWinter visitorUncommon64–79 cmRegularly Nov–Mar
Common TernSterna hirundoPassage migrantRare31–35 cmRegularly Jun–Oct
KittiwakeRissa tridactylaPassage migrantRare37–41 cmRegularly Nov–Dec
Glaucous GullLarus hyperboreusWinter visitorRare62–68 cmRegularly Dec–Mar
Little GullHydrocoloeus minutusPassage migrantRare25–30 cmRegularly Sep
Arctic TernSterna paradisaeaPassage migrantRare33–39 cmRegularly Sep–Oct
Smallest to largest
Length, cm- Black Tern 22–26 cm
- Little Gull 25–30 cm
- Sabine's Gull 27–33 cm
- Bonaparte's Gull 28–38 cm
- Common Tern 31–35 cm
- Franklin's Gull 32–36 cm
- Forster's Tern 33–36 cm
- Arctic Tern 33–39 cm
- Kittiwake 37–41 cm
- Ring-billed Gull 43–54 cm
- Iceland Gull 52–60 cm
- Lesser Black-backed Gull 52–64 cm
- American Herring Gull 53–65 cm
- Glaucous Gull 62–68 cm
- Great Black-backed Gull 64–79 cm
Body length, bill to tail. Rare birds in grey.
Data: EOD – eBird Observation Dataset (Cornell Lab of Ornithology), accessed via GBIF.org, CC BY 4.0. Records from 2019–2024, aggregated and filtered by Birdfact. How these lists are made