Trimeresurus hageni
Silhouette: Steven Traver · PhyloPic
In 3 days ~50% in a week ~80%
Trimeresurus hageni, commonly known as Hagen's pit viper and Hagen's green pit viper, is a species of venomous snake in the subfamily Crotalinae of the family Viperidae. The species is native to Southeast Asia. There are no subspecies that are recognized as being valid.
The specific name, hageni, is in honor of German naturalist Dr. Bernhard Hagen, who collected mammals, birds, reptiles, and insects in the eastern part of Sumatra. Scalation of T. hageni includes 21 rows of dorsal scales at midbody, 176–198 ventral scales, 63–89 subcaudal scales, and 9–12 supralabial scales. The lectotype has a total length (including tail) of 97 cm (38 in).
T. hageni is found in Peninsular Thailand, Peninsular Malaysia, East Malaysia (Borneo), and Indonesia (Sumatra and the nearby islands of Bangka, Simalur, Nias, Batu, and the Mentawai Islands). The type locality given is "Sumatra... [and] island of Banka". Brongersma (1933) emended this to "Deli, Sumatra".
The preferred natural habitat of T. hageni is forest, at altitudes of 100–300 m (330–980 ft). T. hageni is arboreal and nocturnal. T. hageni preys... 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 Hagen’s Pitviper sighting in Gunung Leuser National Park on a given day, based on 12 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 22nd most-seen of the 47 reptiles we can rate there. Over three days the chance rises to about 50%, and over a week to about 80%, if each day is a fresh chance.
March and September
In those months about 40% of wildlife watchers report a Hagen’s Pitviper in Gunung Leuser National Park on a given day, against under 5% in April–August and October–December, the lowest months.
Between 9 pm and midnight
Across all the parks we cover, that three-hour window holds the most Hagen’s Pitviper sightings with a recorded time, and about 8 in 10 of them come between 6 pm and 6 am: it is mostly seen at night.
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 Hagen’s Pitviper sightings: about 20% of wildlife watchers there report one on a given day.
Same genus: Trimeresurus
The closest relatives of the Hagen’s Pitviper that you can see in Gunung Leuser National Park (genus Trimeresurus, Asian Lanceheads) are Gunalen's Pitviper (about 20%) and Sabah Bamboo Pitviper (about 20%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Hagen’s Pitviper is recorded against all the reptiles logged in Gunung Leuser National Park (12 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.
