Sterna paradisaea
Silhouette: Sharon Wegner-Larsen · PhyloPic
In 3 days ~20% in a week ~40%
The Arctic tern (Sterna paradisaea) is a tern in the family Laridae. This bird has a circumpolar breeding distribution covering the Arctic and subarctic regions of Europe (as far south as Brittany), Asia, and North America (as far south as Massachusetts). The species is strongly migratory, seeing two summers each year as it migrates along a convoluted route from its northern breeding grounds to the Antarctic coast for the southern summer and back again about six months later. Recent studies have shown average annual round-trip lengths of about 70,900 km (38,300 nmi) for birds nesting in Iceland and Greenland, and about 48,700 km (26,300 nmi) for birds nesting in the Netherlands, while an individual from the Farne Islands in Northumberland with a light level geolocator tag covered a staggering 96,000 km (52,000 nmi) in ten months from the end of one breeding season to the start of the next. These are by far the longest migrations known in the animal kingdom.
Arctic terns are medium-sized birds. They have a length of 33–36 cm (13–14 in) and a wingspan of 76–85 cm (30–33 in), and weigh around 100 g. In the breeding season they are mainly grey and white, with a blood-red beak and feet, a black crown and nape, and white cheeks. The mantle is grey, and the scapulars grey, tipped white. The upper wing is grey with a white leading edge and a narrow blackish trailing edge on the primary feathers; the collar is completely white, as is the rump. The deeply forked tail is whitish, with grey outer webs. In winter, the forehead becomes partly white, and the bill and legs are black. Juveniles also have a partly white forehead, and narrow pale orangey-brown fringes on the grey mantle feathers (unlike common tern, where the mantle feathers are more completely gingery-brown).
Arctic terns are long-lived birds, with many reaching fifteen to thirty years of age, with a record of 31 years. They eat mainly fish and small marine invertebrates. The species is abundant, with an estimated two million individuals. While the trend in the number of individuals in the species as a whole is not known, exploitation in the past has reduced this bird's numbers in the southern reaches of its ranges. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Svalbard | 🇳🇴 Norway | |
| 2 | Vatnajokull National Park | 🇮🇸 Iceland | |
| 3 | Katmai National Park | 🇺🇸 United States | |
| 4 | Kenai Fjords National Park | 🇺🇸 United States | |
| 5 | Kluane National Park | 🇨🇦 Canada | |
| 6 | Wadden Sea National Park | 🇩🇪 Germany | |
| 7 | Padre Island National Seashore | 🇺🇸 United States | |
| 8 | Gros Morne National Park | 🇨🇦 Canada | |
| 9 | Great Bear Rainforest | 🇨🇦 Canada | |
| 10 | Acadia National Park | 🇺🇸 United States | |
| 11 | Denali National Park | 🇺🇸 United States | |
| 12 | Snowdonia National Park | 🇬🇧 United Kingdom | |
| 13 | Galápagos Islands | 🇪🇨 Ecuador | |
| 14 | Point Pelee National Park | 🇨🇦 Canada |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Anchorage | 🇺🇸 United States | |
| 2 | Dakar | 🇸🇳 Senegal | |
| 3 | Helsinki | 🇫🇮 Finland | |
| 4 | Dublin | 🇮🇪 Ireland | |
| 5 | Liverpool | 🇬🇧 United Kingdom | |
| 6 | Mumbai | 🇮🇳 India | |
| 7 | Stockholm | 🇸🇪 Sweden | |
| 8 | Manchester | 🇬🇧 United Kingdom | |
| 9 | Saint Petersburg | 🇷🇺 Russia | |
| 10 | London | 🇬🇧 United Kingdom |
| # | Zoo / Centre | Country | |
|---|---|---|---|
| 1 | Zoo Pilsen | 🇨🇿 Czechia | |
| 2 | Pyrénées Animal Park | 🇫🇷 France | |
| 3 | Montreal Biodome | 🇨🇦 Canada |
With luck
About 10% of wildlife watchers report an Arctic Tern sighting in Wadden Sea National Park on a given day, based on 663 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 109th most-seen of the 285 birds we can rate there. Over three days the chance rises to about 20%, and over a week to about 40%, if each day is a fresh chance.
May and July
In those months about 20% of wildlife watchers report an Arctic Tern in Wadden Sea National Park on a given day, against under 5% in September to April, the lowest months.
Between 10 am and 1 pm
Across all the parks we cover, that three-hour window holds the most Arctic Tern sightings with a recorded time, and about 8 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
6th of 14
Of the 14 parks where we can rate Arctic Tern sightings, Wadden Sea National Park ranks 6th at about 10%. The best odds are in Svalbard (Norway, about 90%), Vatnajokull National Park (Iceland, about 70%) and Katmai National Park (United States, about 30%).
GBIF citizen-science records
It is estimated from how often the Arctic Tern is recorded against all the birds logged in Wadden Sea National Park (663 verified sightings from 2019 to 2026), 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.
