Sterna sumatrana
Silhouette: Sharon Wegner-Larsen · PhyloPic
In 3 days ~20% in a week ~40%
The black-naped tern (Sterna sumatrana) is an oceanic tern mostly found in tropical and subtropical areas of the Indian Ocean and western Pacific Ocean. They are rarely found inland. It was described from the islands around Sumatra. It is most closely related to roseate tern S. dougallii and white-fronted tern S. striata.
The black-naped tern is named from the black band beginning at the eyes connecting behind the head and descending the back of the neck. The rest of their plumage is white, with pale silvery-grey wings and mantle, apart from the outermost primary feather which has a narrow black outer web. The tail is white, and deeply forked, extending (like the related roseate and white-fronted terns) beyond the wingtips on perched birds. The beaks and legs are black. They have a body length of 30–35 cm and a wingspan of 66 cm. Adults weigh between 97 and 120 g. Hatchlings are mottled brown.
There are two listed subspecies: Sterna sumatrana sumatrana (Raffles, 1822) – islands of the eastern Indian Ocean through to the western Pacific, north to Taiwan and south to Queensland in Australia Sterna sumatrana mathewsi (Stresemann, 1914) – islands of the... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Komodo National Park | 🇮🇩 Indonesia | |
| 2 | Bali Barat National Park | 🇮🇩 Indonesia | |
| 3 | Raja Ampat | 🇮🇩 Indonesia | |
| 4 | Tangkoko Nature Reserve | 🇮🇩 Indonesia |
With luck
About 10% of wildlife watchers report a Black-naped Tern sighting in Bali Barat National Park on a given day, based on 93 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 104th most-seen of the 173 birds we can rate there. Over three days the chance rises to about 20%, and over a week to about 40%, if each day is a fresh chance.
January and July–November
In those months about 10% of wildlife watchers report a Black-naped Tern in Bali Barat National Park on a given day, against under 5% in February–June and December, the lowest months.
Between 9 am and noon
Across all the parks we cover, that three-hour window holds the most Black-naped Tern sightings with a recorded time, and nearly all 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 Black-naped Tern sightings, Bali Barat National Park ranks 2nd at about 10%. The best odds are in Komodo National Park (Indonesia, about 30%).
GBIF citizen-science records
It is estimated from how often the Black-naped Tern is recorded against all the birds logged in Bali Barat National Park (93 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.
