Larus schistisagus
Silhouette: Sharon Wegner-Larsen · PhyloPic
In 3 days ~10% in a week ~20%
The slaty-backed gull (Larus schistisagus) is a large, white-headed gull that breeds on the north-eastern coast of the Palearctic, but travels widely during nonbreeding seasons. It is similar in appearance to the western gull and the glaucous-winged gull. Another alternate name is Pacific gull, though it also applies to a Southern Hemisphere species, L. pacificus.
The genus name is from Latin larus, which appears to have referred to a gull or other large seabird. The specific schistisagus is from Neo-Latin schistus, "slate", and Latin sagus, "cloak". The Slaty-backed Gull is native to the Pacific coast of northeastern Asia. Individuals have strayed to various places throughout North America, including Alaska, New England and Texas. On 3 November 2012, an individual was spotted in Finland. The species has only been spotted three times before in Europe.
It is tied with the yellow-footed gull for fourth-largest gull species, measuring 55–68.5 cm (21.7–27.0 in) in length, 132–160 cm (52–63 in) in wingspan, and 1.05–1.7 kg (2.3–3.7 lb) in weight. Among standard measurements, the wing chord is 40 to 48 cm (16 to 19 in),... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|
More parks will be added in future updates.
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Sapporo | 🇯🇵 Japan | |
| 2 | Busan | 🇰🇷 South Korea | |
| 3 | Tokyo | 🇯🇵 Japan | |
| 4 | New York City | 🇺🇸 United States | |
| 5 | Los Angeles | 🇺🇸 United States | |
| 6 | Nagoya | 🇯🇵 Japan | |
| 7 | Seoul | 🇰🇷 South Korea | |
| 8 | Osaka | 🇯🇵 Japan | |
| 9 | Toronto | 🇨🇦 Canada |
Rare
Under 5% of wildlife watchers report a Slaty-backed Gull sighting in Tokyo on a given day, based on 655 verified sightings from GBIF citizen-science data. It is the 81st most-seen of the 229 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 and September
In those months about 10% of wildlife watchers report a Slaty-backed Gull in Tokyo on a given day, against under 5% in October to July, the lowest months.
Between 8 and 11 am
Across all the parks we cover, that three-hour window holds the most Slaty-backed Gull sightings with a recorded time, and about 8 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
3rd of 9
Of the 9 cities where we can rate Slaty-backed Gull sightings, Tokyo ranks 3rd at under 5%. The best odds are in Sapporo (Japan, about 10%) and Busan (South Korea, about 10%).
GBIF citizen-science records
It is estimated from how often the Slaty-backed Gull is recorded against all the birds logged in Tokyo (655 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.
