Varanus rudicollis
Silhouette: Steven Traver · PhyloPic
In 3 days ~60% in a week ~90%
The black rough-necked monitor (Varanus rudicollis) is a species of monitor lizard found in Southeast Asian countries of Thailand, Burma, and Malaysia. It is also found in Indonesia on Sumatra and islands of the Riau Archipelago It is sometimes known simply as the roughneck monitor. In Thailand is called h̄èā cĥāng (Thai: เห่าช้าง; "elephant bark/roar").
The habitat of Varanus rudicollis is limited to primary and secondary rainforest and mangrove swamps. In the wild the black rough-necked monitor is very rarely seen, but whether this is because of its rarity or its very secretive behavior is uncertain. They are often kept successfully in captivity, but have a shy disposition.
This species is most closely related to its sister group, the water monitor species complex (e.g., the Asian water monitor) which are also in the subgenus Soterosaurus, having split from them 14 million years ago in the middle Miocene.
The black roughneck is a medium to large monitor. It usually reaches an average adult size of 3–4 ft. (90–120 cm), with a maximum length of 5 feet (150 cm), reported. The black rough-necked monitor can be easily recognized by large pointed scales adorning the... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Bako National Park | 🇲🇾 Malaysia | |
| 2 | Danum Valley Conservation Area | 🇲🇾 Malaysia | |
| 3 | Sepilok | 🇲🇾 Malaysia |
| # | Zoo / Centre | Country | |
|---|---|---|---|
| 1 | Detroit Zoo | 🇺🇸 United States | |
| 2 | Silesian Zoological Garden | 🇵🇱 Poland | |
| 3 | Zoo Atlanta | 🇺🇸 United States | |
| 4 | Downtown Aquarium, Houston | 🇺🇸 United States | |
| 5 | National Reptile Zoo | 🇮🇪 Ireland |
Possible
About 30% of wildlife watchers report a Roughneck Monitor sighting in Bako National Park on a given day, based on 7 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 16th most-seen of the 20 reptiles we can rate there. Over three days the chance rises to about 60%, and over a week to about 90%, if each day is a fresh chance.
August
In that month about 40% of wildlife watchers report a Roughneck Monitor in Bako National Park on a given day, against under 5% in January–April, July and October–November, the lowest months.
Between 5 and 8 am
Across all the parks we cover, that three-hour window holds the most Roughneck Monitor sightings with a recorded time, and about half of them come between 6 am and 6 pm: it is most active around dawn and dusk.
Yes
Of the 3 parks where we can rate Roughneck Monitor sightings, Bako National Park has the highest daily chance: about 30%. Next come Danum Valley Conservation Area (Malaysia, about 20%) and Sepilok (Malaysia, about 10%).
GBIF citizen-science records
It is estimated from how often the Roughneck Monitor is recorded against all the reptiles logged in Bako National Park (7 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.
