Chlidonias niger
Silhouette: Andy Wilson · PhyloPic
In 3 days ~10% in a week ~20%
The black tern (Chlidonias niger) is a small tern generally found in or near inland water that breeds in Europe, Western Asia and North America. In winter the birds migrate to coastal areas of Africa and South America. The black tern was formally described in 1758 by the Swedish naturalist Carl Linnaeus in the tenth edition of his Systema Naturae under the binomial name Sterna nigra. Linnaeus specified the type location as Europe but it is now restricted to Uppsala in Sweden. The black tern is now one of four species placed in the genus Chlidonias that was introduced in 1822 by the French naturalist Constantine Rafinesque. The genus name is from Ancient Greek khelidonios, "swallow-like", from khelidon, "swallow": another old English name for the black tern is "carr (i.e. lake) swallow". The species name is from Latin niger "shining black". As its name suggests, it has predominantly dark plumage. In some lights it can appear blue in the breeding season, hence the old English name "blue darr".
Two subspecies are recognised. These are listed below with their breeding ranges. Adults are 25 cm (10 in) long, with a wingspan 61 cm (24 in), and weigh 62... Wikipedia →
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Dakar | 🇸🇳 Senegal | |
| 2 | Accra | 🇬🇭 Ghana | |
| 3 | Bucharest | 🇷🇴 Romania | |
| 4 | Warsaw | 🇵🇱 Poland | |
| 5 | Calgary | 🇨🇦 Canada | |
| 6 | Kyiv | 🇺🇦 Ukraine | |
| 7 | Barranquilla | 🇨🇴 Colombia | |
| 8 | Istanbul | 🇹🇷 Turkey | |
| 9 | Saint Petersburg | 🇷🇺 Russia | |
| 10 | Mexico City | 🇲🇽 México |
Rare
Under 5% of wildlife watchers report a Black Tern sighting in Warsaw on a given day, based on 65 verified sightings from GBIF citizen-science data. It is the 91st most-seen of the 174 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.
May to July
In those months about 10% of wildlife watchers report a Black Tern in Warsaw on a given day, against under 5% in August to April, the lowest months.
Between 11 am and 2 pm
Across all the parks we cover, that three-hour window holds the most Black 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.
4th of 30
Of the 30 cities where we can rate Black Tern sightings, Warsaw ranks 4th at under 5%. The best odds are in Dakar (Senegal, about 30%), Accra (Ghana, about 10%) and Bucharest (Romania, under 5%).
GBIF citizen-science records
It is estimated from how often the Black Tern is recorded against all the birds logged in Warsaw (65 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.
