Larus marinus
Silhouette: Andy Wilson · PhyloPic
In 3 days ~10% in a week ~30%
The great black-backed gull (Larus marinus) is the largest member of the gull and tern family Laridae. It is a very aggressive hunter, pirate and scavenger which breeds on the North Atlantic coasts and islands of northern Europe and northeastern North America. Southern populations are generally sedentary, while those breeding in the far north (northern Norway, northwest Russia) migrate farther south in winter. A few also move inland to large lakes and reservoirs. The adult has a white head, neck and underparts, dark blackish-grey wings and back, pink legs and the bill yellow with a red spot.
The great black-backed gull was one of the many species originally described by Carl Linnaeus in his 1758 10th edition of Systema Naturae, and it still bears its original scientific name of Larus marinus. Larus appears to have referred to a gull or other large seabird. The specific name marinus means "marine", or when taken together, "sea gull". The name predates Linnean taxonomy, as it had been called Larus ingens marinus by Carolus Clusius.
The terms swaabie (from Norn: swartbak, lit. 'black back'), baagie and baigie (Norn: bagi, from Old Norse: bak, lit. 'back') are local names... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Cape Breton Highlands National Park | 🇨🇦 Canada | |
| 2 | Gros Morne National Park | 🇨🇦 Canada | |
| 3 | Acadia National Park | 🇺🇸 United States | |
| 4 | Wadden Sea National Park | 🇩🇪 Germany | |
| 5 | Snowdonia National Park | 🇬🇧 United Kingdom | |
| 6 | Vatnajokull National Park | 🇮🇸 Iceland | |
| 7 | Point Pelee National Park | 🇨🇦 Canada | |
| 8 | Merritt Island National Wildlife Refuge | 🇺🇸 United States | |
| 9 | Svalbard | 🇳🇴 Norway | |
| 10 | Cairngorms National Park | 🇬🇧 United Kingdom | |
| 11 | Everglades National Park | 🇺🇸 United States | |
| 12 | Doñana National Park | 🇪🇸 Spain |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Liverpool | 🇬🇧 United Kingdom | |
| 2 | Dublin | 🇮🇪 Ireland | |
| 3 | Helsinki | 🇫🇮 Finland | |
| 4 | New York City | 🇺🇸 United States | |
| 5 | Montreal | 🇨🇦 Canada | |
| 6 | Boston | 🇺🇸 United States | |
| 7 | Copenhagen | 🇩🇰 Denmark | |
| 8 | Baltimore | 🇺🇸 United States | |
| 9 | Rotterdam [The Hague] | 🇳🇱 Netherlands | |
| 10 | Stockholm | 🇸🇪 Sweden |
With luck
About 10% of wildlife watchers report a Great Black-backed Gull sighting in Philadelphia on a given day, based on 1,308 verified sightings from GBIF citizen-science data. It is the 86th most-seen of the 248 birds we can rate there. Over three days the chance rises to about 10%, and over a week to about 30%, if each day is a fresh chance.
January
In that month about 20% of wildlife watchers report a Great Black-backed Gull in Philadelphia on a given day, against under 5% in March to October, the lowest months.
Between 3 and 6 pm
Across all the parks we cover, that three-hour window holds the most Great Black-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.
14th of 33
Of the 33 cities where we can rate Great Black-backed Gull sightings, Philadelphia ranks 14th at about 10%. The best odds are in Liverpool (United Kingdom, about 40%), Dublin (Ireland, about 40%) and Helsinki (Finland, about 30%).
Same genus: Larus
The closest relatives of the Great Black-backed Gull that you can see in Philadelphia (genus Larus, Large White-headed Gulls) are Ring-billed Gull (about 20%) and American Herring Gull (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Great Black-backed Gull is recorded against all the birds logged in Philadelphia (1,308 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.
