Gelochelidon nilotica
Silhouette: Sheatherius · PhyloPic
In 3 days ~60% in a week ~90%
The gull-billed tern (Gelochelidon nilotica) is a tern in the family Laridae. It is widely distributed and breeds in scattered localities in Europe, Asia, northwest Africa, and the Americas. The Australian gull-billed tern was previously considered a subspecies.
The gull-billed tern was formally described in 1789 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae. He placed it with terns in the genus Sterna and coined the binomial name Sterna nilotica. Gmelin based his description on the "Egyptian tern" that had been described in 1785 by the English ornithologist John Latham in his book A General Synopsis of Birds. Latham had in turn based his own account on that by the Swedish naturalist Fredrik Hasselquist that was published in 1757. The gull-billed tern was moved to the resurrected genus Gelochelidon based on a molecular phylogenetic study published in 2005. The genus had been introduced in 1830 by the German zoologist Christian Ludwig Brehm. The genus name combines the Ancient Greek gelaō meaning "to laugh" with khelidōn meaning "swallow". The specific epithet nilotica is from Latin niloticus meaning... Wikipedia →
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Zanzibar City | 🇹🇿 Tanzania | |
| 2 | Karachi | 🇵🇰 Pakistan | |
| 3 | Kuwait City | 🇰🇼 Kuwait | |
| 4 | Manama | 🇧🇭 Bahrain | |
| 5 | São Luís | 🇧🇷 Brazil | |
| 6 | Dakar | 🇸🇳 Senegal | |
| 7 | Dar es-Salaam | 🇹🇿 Tanzania | |
| 8 | Barranquilla | 🇨🇴 Colombia | |
| 9 | Luxor | 🇪🇬 Egypt | |
| 10 | Mumbai | 🇮🇳 India |
| # | Zoo / Centre | Country | |
|---|---|---|---|
| 1 | Zoobotánico Jerez | 🇪🇸 Spain |
Possible
About 20% of wildlife watchers report a Gull-billed Tern sighting in São Luís on a given day, based on 14 verified sightings from GBIF citizen-science data. It is the 38th most-seen of the 74 birds we can rate there. Over three days the chance rises to about 60%, and over a week to about 90%, if each day is a fresh chance.
October and November
In those months about 50% of wildlife watchers report a Gull-billed Tern in São Luís on a given day, against about 10% in February–August and December, the lowest months. Those are among São Luís's driest months, with about 15 mm of rain a month against 360 mm in April.
Between 9 am and noon
Across all the parks we cover, that three-hour window holds the most Gull-billed 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.
5th of 52
Of the 52 cities where we can rate Gull-billed Tern sightings, São Luís ranks 5th at about 20%. The best odds are in Zanzibar City (Tanzania, about 60%), Karachi (Pakistan, about 30%) and Kuwait City (Kuwait, about 30%).
Same family: Laridae
The closest relatives of the Gull-billed Tern that you can see in São Luís (family Laridae, Gulls, Terns, and Skimmers) are Grey-hooded Gull (about 30%), Large-billed Tern (about 20%) and Black Skimmer (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Gull-billed Tern is recorded against all the birds logged in São Luís (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.
