Thalasseus sandvicensis
Silhouette: JJ Harrison (vectorized by T. Michael Keesey) · PhyloPic
In 3 days ~50% in a week ~80%
The Sandwich tern (Thalasseus sandvicensis) is a tern in the family Laridae. It is very closely related to the lesser crested tern (T. bengalensis), Chinese crested tern (T. bernsteini), Cabot's tern (T. acuflavidus), and elegant tern (T. elegans) and has been known to interbreed with both elegant and lesser crested terns. It breeds in the Palearctic from Europe to the Caspian Sea, and winters in the Mediterranean and on the coasts of Africa, India, and Sri Lanka.
The Sandwich tern is a medium-large tern with pale silvery-grey upperparts, white underparts, a yellow-tipped black bill, and a shaggy black crest which becomes less extensive in winter with a white crown. Young birds bear grey and blackish scalloped plumage on their backs and wings. It is a vocal bird. It nests in a ground scrape and lays one to three eggs.
Like all Thalasseus terns, the Sandwich tern feeds by plunge-diving for fish, usually in marine environments, and the offering of fish by the male to the female is part of the courtship display. The terns are small to medium-sized seabirds, gull-like in appearance, but usually with a more delicate, lighter build and shorter, weaker legs. They have long,... Wikipedia →
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Dakar | 🇸🇳 Senegal | |
| 2 | Algiers | 🇩🇿 Algeria | |
| 3 | Rabat | 🇲🇦 Morocco | |
| 4 | Havana | 🇨🇺 Cuba | |
| 5 | Vitória | 🇧🇷 Brazil | |
| 6 | Kuwait City | 🇰🇼 Kuwait | |
| 7 | Casablanca | 🇲🇦 Morocco | |
| 8 | Liverpool | 🇬🇧 United Kingdom | |
| 9 | Porto | 🇵🇹 Portugal | |
| 10 | Dublin | 🇮🇪 Ireland |
Possible
About 20% of wildlife watchers report a Sandwich Tern sighting in Algiers on a given day, based on 14 verified sightings from GBIF citizen-science data. It is the 12th most-seen of the 49 birds we can rate there. Over three days the chance rises to about 50%, and over a week to about 80%, if each day is a fresh chance.
April
In that month about 30% of wildlife watchers report a Sandwich Tern in Algiers on a given day, against about 20% in March, May and October–December, the lowest months. January–February and June–September have too few records to rate.
Between 9 am and noon
Across all the parks we cover, that three-hour window holds the most Sandwich Tern sightings with a recorded time, and about 9 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
2nd of 50
Of the 50 cities where we can rate Sandwich Tern sightings, Algiers ranks 2nd at about 20%. The best odds are in Dakar (Senegal, about 50%).
GBIF citizen-science records
It is estimated from how often the Sandwich Tern is recorded against all the birds logged in Algiers (14 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.
