Sterna hirundinacea
Silhouette: Sharon Wegner-Larsen · PhyloPic
In 3 days <5% in a week ~10%
The South American tern (Sterna hirundinacea) is a species of tern found in coastal regions of southern South America, including the Falkland Islands, ranging north to Peru (Pacific coast) and Brazil (Atlantic coast). It is generally the most common tern in its range. The smaller, highly migratory common tern closely resembles it. The specific epithet refers to the "swallow-like" forked tail feathering.
With adult South American terns reaching a length of 40 to 44 centimetres (16 to 17 in), they are larger than either common terns (Sterna hirundo) or Arctic terns (Sterna paradisaea). Otherwise they closely resemble these species in plumage at all times of year. The beak is larger and is red in adults, and they do not have a dark-coloured bar on the carpus of the wing. The black cap extends below the eye, usually separated from it by a white crescent, and the rear edge of the cap is neatly defined. Juveniles have boldly-barred, dusky, upper parts, and retain their barred tertials into their immature plumage, which differentiates them from common and Arctic tern immatures.
This tern is found around the coasts of the southern half of South America... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Península Valdés | 🇦🇷 Argentina | |
| 2 | Tierra del Fuego National Park | 🇦🇷 Argentina | |
| 3 | Torres del Paine National Park | 🇨🇱 Chile | |
| 4 | Tijuca National Park | 🇧🇷 Brazil |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Vitória | 🇧🇷 Brazil | |
| 2 | Montevideo | 🇺🇾 Uruguay | |
| 3 | Rio de Janeiro | 🇧🇷 Brazil | |
| 4 | Lima | 🇵🇪 Peru |
Rare
Under 5% of wildlife watchers report a South American Tern sighting in Rio de Janeiro on a given day, based on 53 verified sightings from GBIF citizen-science data. It is the 165th most-seen of the 278 birds we can rate there. Over three days the chance rises to under 5%, and over a week to about 10%, if each day is a fresh chance.
Any time of year
In every month with enough records, under 5% of wildlife watchers report a South American Tern in Rio de Janeiro on a given day, so our monthly data shows no clear season.
Between 10 am and 1 pm
Across all the parks we cover, that three-hour window holds the most South American 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.
Among the best
Of the 4 cities where we can rate South American Tern sightings, Rio de Janeiro ranks 3rd at under 5%, level with the leaders once rounded. The best odds are in Vitória (Brazil, under 5%) and Montevideo (Uruguay, under 5%).
GBIF citizen-science records
It is estimated from how often the South American Tern is recorded against all the birds logged in Rio de Janeiro (53 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.
