Reptilia · Squamata
Varanus rosenbergiMertens, 1957
Heath Monitor
Photograph by Paul Asman and Jill Lenoble, CC BY, via iNaturalist
A ground-dwelling, day-active, meat-eating monitor lizard from the Australo-Pacific region, reaching 518 mm snout to vent.
Reptilia › Squamata › Varanidae › Varanus
- Grows to
- 518mm
- greatest recorded
- Eats
- Carnivorous
- Active
- Diurnal
- Lives up to
- 18.3years
Longer than 62% of all monitor lizards anyone has measured.
The bar is the rank itself: its length is the share of the family this animal exceeds. The chart below is the family’s real spread, on a logarithmic scale because body length here runs from 116.4 to 1,570 mm. The solid rule is this animal. Every bar is a count of real species, and nothing on this figure is estimated.
What is known
43 sourced facts, each taken from a named scientific dataset. How to read these.
Cited from a dataset unless a row is marked otherwise.
Standing in the world
- Still living
- Extant
- Conservation status
- Least Concern
- Status assessed · the year the Red List last looked
- 2017
The animal itself
- Limbs
- Four legs
- Fangs
- None
- Longest recorded life
- 18.3years
- Preferred body temperature · chosen in a laboratory gradientmeasured
- 35.2°C
- Body temperature when active · measured in the wild
- 26.85°C80 °F
- Body temp in the wild · mean, when active
- 17.4–36.3°C63–97 °F
Myhrvold, Baldridge, Chan, Sivam, Freeman, and Ernest, 2015, Ecology, 96:3109-3109
mean body temperature of active individuals in nature
body temperature of active animals in nature
Size
- Length snout to vent · greatest recorded
- 518mm20.5 in
- Length snout to vent · adult female mean
- 320.4mm12.5 in
- Largest female · snout to vent
- 320.4mm12.5 in
- Hatchling length · snout to vent
- 111mm4.25 in
- Largest juvenile · snout to vent
- 111mm4.25 in
- Body mass · greatestcomputed
- 3019g6.7 lb
- Body mass · adult female, meanmeasured
- 1088g2.4 lb
- Body mass at hatchingmeasured
- 19g0.67 oz
max 518 mm SVL (Feldman et al. 2016)
snout-vent length; the source column mixes this with straight carapace length
computed from length by a family-level allometric equation, not weighed
How it lives
- Diet
- Carnivorous
- How it hunts
- Active foraging
- Active
- Diurnal
- Where it lives
- Terrestrial
- Habitat
- Forest, Shrubland
- Biome
- Mediterranean
- Active season · months of the year
- 8–12months
- Region
- Australo-Pacific
- Mainland or island
- Mainland
- Elevation · above sea level
- 100–110m
- Range size
- 413,081km²
- Home range · largest recorded
- 437,000m2
Vertebrates, carrion and invertebrates (e.g., Arbuckle 2009, Auliya and Koch 2020), "insects, spiders, scorpions frogs, snakes, lizards, small birds and small mammals (Houston & Tyler 1979). King & Green (1979) found that mammals (especiaUy rodents) and invertebrates (roaches, orthopterans, spiders, scorpions, beetles, centipedes and moUuscs) account for two-thirds of all food taken on Kangaroo Island. The remainder of the diet is made up of frogs, reptiles, lizard eggs and birds." (Bennett 1995), birds, mammals, reptiles, frogs and invertebrates (Robertson and Coventry 2019)
e.g., Clemente et al. 2009
e.g., Swan et al. 2017, Robertson and Coventry 2019, Swan 2020, Auliya and Koch 2020
Breeding
- Reproduction
- Oviparous
- Sex decided by
- Genes, ZW/ZZ
- Average clutch
- 8.25eggs
- Eggs or young per clutch
- 3–19eggs
- Mean clutch
- 4–12.5eggs
- Clutches a year
- 0.3–1per year
- First breeds at
- 18–36months
6-12 (Swan and Watharow 2005), "mean clutch size (N = 11) was 12.5±0.73 eggs, similar to the mean of 11.9 eggs reported by Rismiller et al. (2010)." (Andrews et al. 2017), 12-19 (Robertson and Coventry 2019), 3-19 (Auliya and Koch 2020)
Naming and history
- Suborder
- Sauria
- Infraorder
- Anguimoprha
- Subspecies
- No
- Described by
- Mertens
- Moved to another genus · since it was first described
- No
- Described in
- 1957
- Type locality
- Australia
Keeping one
6 ft 10 in × 6 ft 10 in × 4 ft 3 in(207 × 207 × 130 cm)
Minimum length × width × height, for one animal. Bigger is always better.
The standard sizes ground-dwelling species at 4 × 4 × 2.5 times snout-vent length.
Mindestanforderungen an die Haltung von Reptilien (Sachverständigengutachten), German Federal Ministry for Nutrition, Agriculture and Forestry, Animal Welfare Division, 10 January 1997. The standard states these floor areas are recommendations rather than binding limits.
From this animal’s own snout-vent length of 20.5 in (518 mm), at 4 × 4 × 2.5 times it, following the German federal welfare standard — how this is worked out.
In a laboratory thermal gradient this species settled at 95 °F (35.2 °C).
Preferred body temperature, recorded in a laboratory gradient where the animal could choose freely. A measurement of the animal, not a setting for a thermostat.
Feeding
A prey item should be no wider than the space between the animal's eyes.
Widely used across reptile husbandry references. The stated reason is that the gap approximates the width of the throat, so wider prey is associated with impaction. This is established practice, not a measurement.
243kJ per day
Worked out for an animal of 3,019 g, the heaviest recorded for Heath Monitor — so it is the top of the range, not a figure for a particular animal. Weigh yours and the number will be lower.
An upper estimate, not a feeding target, and not veterinary advice. The equation covers only what an animal burns staying alive, so a growing, gravid or recovering animal needs more — and it was measured on wild animals, which move far more than one in an enclosure. Body condition and a vet who knows the species are what a feeding decision should rest on. Where this comes from.
What nobody knows
These are not gaps in our research. No scientific dataset records them for this species — and saying so is information you cannot get from a reference that simply leaves a field out.
- — Length snout to vent · adult male mean
- — Length snout to vent · adult mean
- — Length nose to tail · greatest recorded
- — Female length · mean, nose to tail
- — Length nose to tail · adult male mean
- — Length nose to tail · adult mean
- — Largest male · snout to vent
- — Largest female · shell length
- — Largest male · shell length
- — Hatchling length · nose to tail
- — Largest juvenile · shell length
- — Egg length
- — Egg width
- — Body mass · a typical adult
- — Eats arthropods
- — Eats vertebrates
- — Eats plant matter
- — How the young develop
- — Gestation or incubation
- — Clutches in a year
- — Hatchling length · smallest recorded
- — Hatchling length · largest recorded
- — Age at first breeding · female
- — Mature from · youngest recorded
- — Mature by · oldest recorded
- — Size at maturity · smallest recorded
- — Size at maturity · largest recorded
- — Venomous
- — Colour on the back
- — Pattern on the back
- — Pupil
- — Population trend
- — Red List criteria
- — Density · lowest recorded
- — Density · highest recorded
- — Active in
Others in Varanidae
Take this data
Everything on this page is available as data under CC BY 4.0 — use it freely, credit it, no permission needed.
This species as JSON · the whole dataset
Cite this page
The Reptile & Amphibian Encyclopedia (2026). Varanus rosenbergi. Retrieved 2026-09-08, from https://www.allanglescreatures.com/species/varanus-rosenbergi
@misc{varanus_rosenbergi_2026,
title = {Varanus rosenbergi},
author = {{The Reptile & Amphibian Encyclopedia}},
year = {2026},
url = {https://www.allanglescreatures.com/species/varanus-rosenbergi}
}Sources
- Meiri, S. (2024). SquamBase — a database of squamate (Reptilia: Squamata) traits. Global Ecology and Biogeography. Public domain (CC0).
- Oskyrko, O. et al. (2024). ReptTraits: a comprehensive dataset of ecological traits in reptiles. Scientific Data. Used under CC BY 4.0.
- Catalogue of Life (dataset 3LR), used under CC BY.
- Moura, M. R. et al. TetrapodTraits: a database of 33,281 tetrapod species. Used under CC BY 4.0. Observed values only; this encyclopedia does not publish its imputed predictions.