Hoolock hoolock
Silhouette: PhyloPic
In 3 days ~80% in a week >90%
The western hoolock gibbon (Hoolock hoolock) is a primate from the gibbon family, Hylobatidae. The species is found in Assam, Mizoram, and Meghalaya in India, Bangladesh, and Myanmar west of the Chindwin River. Mootnick and Groves stated that hoolock gibbons do not belong in the genus Bunopithecus, and placed them in a new genus, Hoolock. This genus was argued to contain two and later three distinct species, which were previously thought to be subspecies: H. hoolock, H. leuconedys, and H. tianxing. A larger evolutionary distance was later found to exist between these three species and the white-handed gibbons than between bonobos and chimpanzees.
A new subspecies of the western hoolock gibbon has been described recently from northeastern India, which has been named the Mishmi Hills hoolock gibbon, H. h. mishmiensis. Like other gibbons, hoolock gibbon pairs produce a loud, elaborate song, usually as a duet from the forest canopy, in which younger individuals of the family group may join. The song includes an introductory sequence, an organising sequence, and a great call sequence, with the male also contributing to the latter (unlike in some other... Wikipedia →
Song1:10
Bangladesh · 2024
© Ding Li Yong · XC961312 · CC BY-NC-ND 4.0
Call0:37
India · 2024
© Lars Lachmann · XC1045821 · CC BY-NC-SA 4.0
Recording2:33
India · 2025
© capepolly · iNaturalist · CC BY-NC 4.0
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Namdapha National Park | 🇮🇳 India | |
| 2 | Kaziranga National Park | 🇮🇳 India |
| # | Zoo / Centre | Country | |
|---|---|---|---|
| 1 | Fota Wildlife Park | 🇮🇪 Ireland | |
| 2 | 西霞口神雕山野生動物世界 | 🇨🇳 China |
Likely
About 50% of wildlife watchers report a Western Hoolock Gibbon sighting in Kaziranga National Park on a given day, based on 28 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 13th most-seen of the 16 mammals 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.
March
In that month about 70% of wildlife watchers report a Western Hoolock Gibbon in Kaziranga National Park on a given day, against about 10% in June–July and October, the lowest months. That is one of Kaziranga National Park's driest months, with about 95 mm of rain against 520 mm in June.
Between 3 and 6 am
Across all the parks we cover, that three-hour window holds the most Western Hoolock Gibbon sightings with a recorded time, and about 6 in 10 of them come between 6 pm and 6 am: it is most active around dawn and dusk.
Among the best
Of the 2 parks where we can rate Western Hoolock Gibbon sightings, Kaziranga National Park ranks 2nd at about 50%, level with the leaders once rounded. The best odds are in Namdapha National Park (India, about 50%).
Same order: Primates
The closest relatives of the Western Hoolock Gibbon that you can see in Kaziranga National Park (order Primates) are Rhesus Macaque (about 70%) and Capped Langur (about 50%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Western Hoolock Gibbon is recorded against all the mammals logged in Kaziranga National Park (28 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.
