Mertens's Water Monitor

Mertens's Water Monitor

Varanus mertensi

Silhouette: Steven Traver · PhyloPic

Least ConcernNear ThreatenedVulnerableEndangeredCritically Endangered Endemic
Daily sighting probability ~40% · Likely
at Nitmiluk National Park
12 Verified sightings at Nitmiluk National Park From 2019 to 2026
196 Verified sightings across all 3 parks From 2019 to 2026
March Best month highest sighting rate
☀️ Diurnal When it's spotted during daytime hours (6am–6pm)

About the Mertens's Water Monitor

Mertens' water monitor (Varanus mertensi) is a species of monitor lizard in the family Varanidae. The species is native to northern Australia, and is a wide-ranging, actively foraging, opportunistic predator of aquatic and riparian habitats. It is named after German herpetologist Robert Mertens.

Mertens' water monitor grows to a total length (tail included) of about 2.0 m (6.6 ft). It is dark brown to black above, with many cream to yellow spots. The underparts are paler – white to yellowish – with grey mottling on the throat and blue-grey bars on the chest. The tail is strongly compressed laterally, with a high median dorsal keel, and is about 1.5 times the length of head and body.

Amongst all monitor species, including even the water monitors of the subgenus Soterosaurus, Mertens' water monitor is morphologically the most well adapted to an aquatic lifestyle, being able to seal its upwards facing nostrils when underwater. It is capable of swallowing prey underwater, which is an ability not reported in any other monitor species other than the Borneo earless monitor (Lanthanotus borneensis). It is also the only monitor species reported capable of using its sense... Wikipedia →

Global Distribution

Warmer areas are where this animal is recorded most often.

Parks Where Found

# Park Country Daily sighting probability
1 Litchfield National Park 🇦🇺 Australia
~90%
2 Nitmiluk National Park 🇦🇺 Australia
~40%
3 Kakadu National Park 🇦🇺 Australia
~30%

Quick answers

What are the chances of seeing a Mertens's Water Monitor in Nitmiluk National Park?

About 40% of wildlife watchers report a Mertens's Water Monitor sighting in Nitmiluk National Park, based on 12 verified sightings from GBIF citizen-science data.

When is the best time to see Mertens's Water Monitor in Nitmiluk National Park?

March has the highest sighting rate for Mertens's Water Monitor in Nitmiluk National Park in our monthly data.

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