Sterna hirundinacea
Silhouette: Sharon Wegner-Larsen · PhyloPic
In 3 days ~80% 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 |
Likely
About 40% of wildlife watchers report a South American Tern sighting in Península Valdés on a given day, based on 199 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 20th most-seen of the 96 birds we can rate there. Over three days the chance rises to about 80%, and over a week to over 90%, if each day is a fresh chance.
January–February and November
In those months about 50% of wildlife watchers report a South American Tern in Península Valdés on a given day, against about 30% in April–May and August–October, the lowest months. June and July have 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.
Yes
Of the 4 parks where we can rate South American Tern sightings, Península Valdés has the highest daily chance: about 40%. Next come Tierra del Fuego National Park (Argentina, about 30%) and Torres del Paine National Park (Chile, about 10%).
Same family: Laridae
The closest relatives of the South American Tern that you can see in Península Valdés (family Laridae, Gulls, Terns, and Skimmers) are Dominican Gull (over 90%), Dolphin Gull (about 40%) and Royal Tern (about 40%), 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 Península Valdés (199 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.
