Sterna hirundinacea
Silhouette: Sharon Wegner-Larsen · PhyloPic
In 3 days ~60% in a week ~90%
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 |
Possible
About 30% of wildlife watchers report a South American Tern sighting in Tierra del Fuego National Park on a given day, based on 299 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 30th most-seen of the 78 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.
February
In that month about 60% of wildlife watchers report a South American Tern in Tierra del Fuego National Park on a given day, against about 10% in May, August and October–November, the lowest months. June has too few records to rate.
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.
2nd of 4
Of the 4 parks where we can rate South American Tern sightings, Tierra del Fuego National Park ranks 2nd at about 30%. The best odds are in Península Valdés (Argentina, about 40%).
Same family: Laridae
The closest relatives of the South American Tern that you can see in Tierra del Fuego National Park (family Laridae, Gulls, Terns, and Skimmers) are Dominican Gull (about 70%) and Dolphin Gull (about 20%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the South American Tern is recorded against all the birds logged in Tierra del Fuego National Park (299 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.
