Presbytis sumatrana
Silhouette: PhyloPic
In 3 days ~40% in a week ~70%
The black Sumatran langur (Presbytis sumatrana) is a species of monkey in the family Cercopithecidae. It was formerly considered a subspecies of the Sumatran surili, Presbytis melalophos (as Presbytis melalophos sumatrana) but genetic analysis revealed that these are separate species. The black Sumatran langur is native to the island of Sumatra in Indonesia. It is listed as endangered by the IUCN due primarily to deforestation, and also due to animals taken for pets. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Gunung Leuser National Park | 🇮🇩 Indonesia |
More parks will be added in future updates.
Possible
About 20% of wildlife watchers report a Black Sumatran Langur sighting in Gunung Leuser National Park on a given day, based on 11 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 12th most-seen of the 19 mammals we can rate there. Over three days the chance rises to about 40%, and over a week to about 70%, if each day is a fresh chance.
September
In that month about 40% of wildlife watchers report a Black Sumatran Langur in Gunung Leuser National Park on a given day, against under 5% in January, March–May, July and November, the lowest months. That is one of Gunung Leuser National Park's wettest months, with about 700 mm of rain against 150 mm in February.
Between 3 and 6 pm
Across all the parks we cover, that three-hour window holds the most Black Sumatran Langur sightings with a recorded time, and about 9 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
Only Gunung Leuser National Park, in our data
Gunung Leuser National Park is the only park on Wallace's Line with enough records to rate Black Sumatran Langur sightings: about 20% of wildlife watchers there report one on a given day.
GBIF citizen-science records
It is estimated from how often the Black Sumatran Langur is recorded against all the mammals logged in Gunung Leuser National Park (11 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.
