Larus heermanni
Silhouette: Sharon Wegner-Larsen · PhyloPic
In 3 days ~10% in a week ~20%
Heermann's gull (Larus heermanni) is a gull resident in the United States, Mexico and extreme southwestern British Columbia, nearly all nesting on Isla Rasa in the Gulf of California. They are usually found near shores or well out to sea, very rarely inland. The species is named after Adolphus Lewis Heermann, nineteenth-century explorer and naturalist.
This species looks distinctly different from other gulls. Adults have a medium gray body, blackish-gray wings and tail with white edges, and a red bill with a black tip. The head is dusky gray in non-breeding plumage and white in breeding plumage. Immatures resemble non-breeding adults but are darker and browner, and the bill is pink till the second winter. A few birds, no more than 1 in 200, have white primary coverts, which form a showy spot on the upper wing. This gull is unlikely to be confused with other species as it is the only white-headed, gray-bodied gull found on the west coast of North America.
Calls are described as deep and similar in pattern to other gulls but is noticeably different in quality. Of the current population of about 150,000 pairs, 90% nest on the island of Isla Rasa off... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Channel Islands National Park | 🇺🇸 United States | |
| 2 | El Vizcaíno Biosphere Reserve | 🇲🇽 Mexico | |
| 3 | Bahía de Loreto National Park | 🇲🇽 Mexico | |
| 4 | Cabo Pulmo National Park | 🇲🇽 Mexico | |
| 5 | Olympic National Park | 🇺🇸 United States | |
| 6 | Redwood National Park | 🇺🇸 United States | |
| 7 | Pacific Rim National Park Reserve | 🇨🇦 Canada | |
| 8 | Carara National Park | 🇨🇷 Costa Rica |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | San Diego | 🇺🇸 United States | |
| 2 | Tijuana | 🇲🇽 México | |
| 3 | Los Angeles | 🇺🇸 United States | |
| 4 | Miami | 🇺🇸 United States | |
| 5 | Seattle | 🇺🇸 United States | |
| 6 | San Francisco | 🇺🇸 United States | |
| 7 | Baltimore | 🇺🇸 United States | |
| 8 | Vancouver | 🇨🇦 Canada |
Rare
Under 5% of wildlife watchers report a Heermann's Gull sighting in Seattle on a given day, based on 2,107 verified sightings from GBIF citizen-science data. It is the 114th most-seen of the 271 birds we can rate there. Over three days the chance rises to about 10%, and over a week to about 20%, if each day is a fresh chance.
August to November
In those months about 10% of wildlife watchers report a Heermann's Gull in Seattle on a given day, against under 5% in December to July, the lowest months.
Between 11 am and 2 pm
Across all the parks we cover, that three-hour window holds the most Heermann's Gull sightings with a recorded time, and nearly all of them come between 6 am and 6 pm: it is a daytime animal.
5th of 8
Of the 8 cities where we can rate Heermann's Gull sightings, Seattle ranks 5th at under 5%. The best odds are in San Diego (United States, about 20%), Tijuana (México, about 20%) and Los Angeles (United States, under 5%).
Same genus: Larus
The closest relatives of the Heermann's Gull that you can see in Seattle (genus Larus, Large White-headed Gulls) are Glaucous-winged Gull (about 40%), Short-billed Gull (about 10%) and Ring-billed Gull (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Heermann's Gull is recorded against all the birds logged in Seattle (2,107 verified sightings), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
