Chroicocephalus philadelphia
Silhouette: Michael Scroggie · PhyloPic
In 3 days ~10% in a week ~20%
Bonaparte's gull (Chroicocephalus philadelphia) is a gull found mainly in northern North America. At 28 to 38 cm (11 to 15 in) in length, it is one of the smallest species of gull. Its plumage is mainly white with grey upperparts. During breeding season, Bonaparte's gull gains a slaty-black hood. The sexes are similar in appearance.
When George Ord first described Bonaparte's gull in 1815, he gave it the scientific name Sterna philadelphia, and the English name 'Banded-tail Tern'; the description clearly identifies it as a bird in first-winter plumage, while "The slender and tern-like form of the bill probably induced Mr. Ord to put it in Sterna". Most later taxonomists assigned it to the genus Larus, a longtime catch-all for most of the gull species. However, in 1858, George Newbold Lawrence moved the species to the genus Chroicocephalus, and some taxonomists followed suit. Subsequent molecular DNA studies have shown that this species fits neatly into a clade with other Chroicocephalus "hooded" gulls, and that it is in a close-to-basal position in that grouping. Based on these studies, the American Ornithologists' Union, which had previously assigned the... Wikipedia →
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Anchorage | 🇺🇸 United States | |
| 2 | Dallas | 🇺🇸 United States | |
| 3 | San Diego | 🇺🇸 United States | |
| 4 | Seattle | 🇺🇸 United States | |
| 5 | Los Angeles | 🇺🇸 United States | |
| 6 | Miami | 🇺🇸 United States | |
| 7 | Orlando | 🇺🇸 United States | |
| 8 | Vancouver | 🇨🇦 Canada | |
| 9 | Montreal | 🇨🇦 Canada | |
| 10 | San Francisco | 🇺🇸 United States |
| # | Zoo / Centre | Country | |
|---|---|---|---|
| 1 | Ralph Perkins II Wildlife Center and Woods Garden | 🇺🇸 United States |
Rare
Under 5% of wildlife watchers report a Bonaparte's Gull sighting in San Diego on a given day, based on 1,022 verified sightings from GBIF citizen-science data. It is the 169th most-seen of the 386 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.
January
In that month about 10% of wildlife watchers report a Bonaparte's Gull in San Diego on a given day, against under 5% in February to December, the lowest months. That is one of San Diego's wettest months, with about 40 mm of rain against almost none in July.
Between 2 and 5 pm
Across all the parks we cover, that three-hour window holds the most Bonaparte's Gull sightings with a recorded time, and about 9 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
3rd of 29
Of the 29 cities where we can rate Bonaparte's Gull sightings, San Diego ranks 3rd at under 5%. The best odds are in Anchorage (United States, about 30%) and Dallas (United States, under 5%).
Same family: Laridae
The closest relatives of the Bonaparte's Gull that you can see in San Diego (family Laridae, Gulls, Terns, and Skimmers) are Western Gull (about 60%), Royal Tern (about 20%) and Ring-billed Gull (about 20%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Bonaparte's Gull is recorded against all the birds logged in San Diego (1,022 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.
