B
Species Profile

Black Throat Monitor

Varanus albigularis ionidesi

Dark throat. Big brain. Savanna hunter.
Aaron Johnston/Shutterstock.com

Black Throat Monitor Distribution

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Endemic Species
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Found in 1 country

Monitor lizard facts - black throat monitor lizard on a leash

At a Glance

Wild Species
Diet Carnivore
Activity Diurnal+
Lifespan 12 years
Weight 15 lbs
Status Not Evaluated
Did You Know?

It's not a full species: Ionides' monitor is a subspecies within the white-throated monitor complex (Varanus albigularis).

Scientific Classification

A large African monitor lizard (white-throated monitor complex). The ‘black-throated monitor’ name is commonly applied to the Tanzanian subspecies noted for a darker throat and robust build.

Kingdom
Animalia
Phylum
Chordata
Class
Reptilia
Order
Squamata
Family
Varanidae
Genus
Varanus
Species
albigularis

Distinguishing Features

  • Darkened throat/neck compared with many other white-throated monitor forms
  • Large, heavy-bodied monitor with strong limbs and claws adapted for digging
  • Typical varanid traits: long neck, forked tongue, alert posture, powerful tail

Physical Measurements

Length
5 ft 3 in (3 ft 11 in – 6 ft 7 in)
Weight
18 lbs (9 lbs – 33 lbs)
Tail Length
3 ft 1 in (2 ft 4 in – 3 ft 11 in)
Top Speed
11 mph
No subspecies data; ~15–20 km/h
Venomous

Appearance

Primary Colors
Secondary Colors
Skin Type Dry, keratinized reptile scales: small pebbly dorsal scales; larger flat ventral scutes; strong muscular tail with ringed scale rows; long flattened sideways claws for digging and tearing; forked tongue to smell and find food.
Distinctive Features
  • Subspecies within the white-throated monitor (Varanus albigularis) complex; commonly characterized (in field and husbandry literature) by a darker gular/throat region and a notably robust, heavy-bodied build relative to some other V. albigularis subspecies.
  • Head broad with strong jaw musculature; neck thick; limbs powerful with long claws-overall morphology consistent with a large-bodied, terrestrial savanna/woodland varanid.
  • Dorsal pattern of many small pale ocelli/speckles on a dark brown/gray background; limbs similarly speckled; tail often faintly banded (pattern typically sharper in juveniles).
  • Active by day, searches for food, and often uses burrows, self-dug retreats, or termite mounds and earth banks for shelter and to control body temperature, matching V. albigularis complex accounts.
  • Few published size and age data exist for Varanus albigularis ionidesi; many numbers cover the whole species. To tell this subspecies, use location plus dark throat and overall body build.

Sexual Dimorphism

As in many large Varanus, dimorphism is typically expressed as males averaging larger with proportionally broader heads/neck and a thicker tail base; females are usually smaller-bodied with a less massive head. External dimorphism can be subtle without direct comparison.

  • Often larger overall body size and mass (reported generally for V. albigularis complex; subspecies-specific averages are not consistently published).
  • Broader head with more pronounced jowls/jaw musculature; thicker neck and shoulders.
  • More obvious hemipenal bulges and thicker tail base posterior to the cloaca in mature males.
  • Typically smaller, with comparatively narrower head and less bulky neck/shoulders.
  • Tail base usually less swollen; absence of hemipenal bulges.
  • Gravid females may show noticeable abdominal distension during the reproductive season (appearance change rather than a fixed trait).

Did You Know?

It's not a full species: Ionides' monitor is a subspecies within the white-throated monitor complex (Varanus albigularis).

The "black-throated" look is largely a darker gular (throat) region-one reason Tanzanian animals became popular in the pet trade.

Like other Varanus, it "smells" with its forked tongue, delivering chemical cues to the Jacobson's organ to track food.

It commonly uses (and may enlarge) burrows and can also take refuge in termite mounds-ready-made, insulated shelters.

Its diet is famously broad: invertebrates (including beetles and snails), eggs, small vertebrates, and carrion-an opportunistic savanna omnivore-carnivore.

Monitor lizards as a group are among the most wide-ranging lizards on Earth: Varanus spans tiny species under 30 cm to giants over 2 m-Ionides' monitor sits in the large-bodied middle.

The subspecies name honors C. J. P. Ionides ("the Snake Man of Tanganyika"), a historically notable East African reptile collector/handler.

Unique Adaptations

  • Forked tongue + vomeronasal (Jacobson's) organ: high-resolution chemical tracking to locate prey, carrion, and possibly conspecific scent trails.
  • Powerful jaw mechanics and recurved, serrated teeth: effective for gripping and tearing tough prey items and carcasses.
  • Robust limbs and claws: specialized for digging and for ripping into rotting logs, termite structures, and soil to access hidden prey.
  • Thick, muscular tail: propulsion during sprinting and a primary defensive weapon (tail-whip).
  • Physiological endurance typical of varanids: monitors have relatively high aerobic capacity for lizards, supporting long, active foraging bouts.
  • Heavily built body with protective scalation (varanid osteoderms may be present to varying degrees): helps resist bites/scratches when digging or subduing prey.

Interesting Behaviors

  • Diurnal, wide-ranging active foraging: moves with head down, tongue-flicking rapidly to sample scent trails and locate hidden prey.
  • Burrow use: retreats to self-dug or appropriated burrows; may repeatedly use the same refuge, especially in suitable soil or mound systems.
  • Termite-mound association: uses mounds as shelter and as foraging sites where insects and other prey concentrate.
  • Opportunistic scavenging: will feed on carrion when available, which can reduce time/energy costs compared with hunting.
  • Defensive repertoire: inflates body, hisses, tail-whips, and can deliver deep bites; typically prefers retreat when an escape route exists.
  • Thermoregulation cycles: alternates basking with foraging; activity peaks tend to track warm daylight hours in savanna/woodland climates.
  • Seasonal shifts (species-complex level): activity and ranging can change with rainfall and prey availability, with increased use of refuges during cooler periods.

Cultural Significance

In parts of eastern and southern Africa, the Black-throated Monitor (Varanus albigularis ionidesi) is known, feared, and respected; hunted for raiding poultry and for skins, yet valued for eating pests and cleaning up dead animals. Its name links this Tanzanian form to collector C. J. P. Ionides.

Myths & Legends

Southern African settler folklore about large monitor lizards sometimes claimed they could steal milk from livestock at night-an enduring rural superstition used to explain unexplained drops in milk or restless animals.

In farming communities, monitors have long been cast in cautionary tales as cunning chicken-house raiders that learn routines and return repeatedly, reinforcing their reputation for persistence and "craftiness."

C. J. P. Ionides, the 'Snake Man of Tanganyika', became a larger-than-life figure in East African reptile tales. Animals named for him, like this Ionides' monitor, link to collector legends of bushcraft and dangerous captures.

Conservation Status

NE Not Evaluated (this subspecies has not been assessed separately by the IUCN; the species Varanus albigularis is assessed at the species level)

Has not yet been evaluated against the criteria.

Population Unknown

Protected Under

  • CITES Appendix II (genus Varanus generally listed; international commercial trade is regulated via permits).
  • Tanzania: Wildlife Conservation Act, 2009 (national framework regulating hunting, possession, and trade of wildlife; applicability depends on schedules/permits and enforcement).

Life Cycle

Birth 12 hatchlings
Lifespan 12 years

Lifespan

In the Wild
8–15 years
In Captivity
15–25 years

Reproduction

Mating System Data Deficient
Social Structure Solitary
Breeding Pattern Seasonal
Fertilization Internal Fertilization
Birth Type Internal_fertilization

Mating system for Varanus albigularis ionidesi is data deficient. Likely solitary except during seasonal breeding; males search, compete and may wrestle for access, with multiple mating. Fertilization is internal (hemipenes); oviparous; hatchlings independent.

Behavior & Ecology

Social None (solitary) Group: 1
Activity Diurnal, Matutinal, Vespertine
Diet Carnivore Bird and reptile eggs (highly targeted when nests are located)
Seasonal Hibernates

Temperament

Primarily wary/avoidant in the wild; tends to flee to burrows/cover when approached (general Varanus albigularis complex pattern; subspecies-specific temperament studies for ionidesi are not well documented).
Defensive escalation when cornered: body inflation, open-mouth threat display, hissing, tail-whipping; biting possible-typical of large varanids (Auffenberg 1981; Bennett 1995).
Intraspecific aggression most evident among adult males during the breeding season or in contests over food/basking sites; ritualized threat displays may precede contact (Auffenberg 1981).

Communication

Hissing/forceful exhalation during defensive displays Widely reported for varanids; described in varanid behavioral accounts such as Auffenberg 1981
Chemical: frequent tongue-flicking to sample odors and deliver them to the vomeronasal Jacobson's) organ; used for prey tracking and conspecific assessment (Auffenberg 1981; Cooper & Vitt 1986, varanid chemoreception
Chemical: scent marking via cloacal secretions/feces and investigation of scent trails; commonly reported in monitor lizards for territory/reproductive context Auffenberg 1981; Bennett 1995
Visual: threat/assessment displays including body elevation, lateral compression, gular/throat inflation, open-mouth display, and orientation/approach-retreat sequences; used in both defense and intraspecific interactions Auffenberg 1981
Tactile Courtship/agonistic): contact behaviors such as climbing onto the female, neck/torso gripping during copulation; grappling may occur between males (Auffenberg 1981; Bennett 1995

Habitat

Biomes:
Savanna Tropical Dry Forest
Terrain:
Plains Coastal Riverine Rocky Sandy
Elevation: Up to 5905 ft 6 in

Ecological Role

Opportunistic terrestrial mesopredator and facultative scavenger in East African savanna/woodland mosaics (within the V. albigularis complex range).

Regulates populations of large insects and other invertebrates (predation pressure on beetles/orthopterans, etc.) Contributes to control of small-vertebrate populations (notably rodents and small reptiles) Carrion removal, accelerating nutrient recycling and reducing persistence of carcasses Influences nesting success of ground- and low-nesting fauna through egg/nestling predation (trophic effects on local recruitment)

Diet Details

Main Prey:
Large insects Other invertebrates Snails Reptile eggs and hatchlings Bird eggs and nestlings Small mammals Other small vertebrates Carrion +2

Human Interaction

Domestication Status

Wild

Varanus albigularis ionidesi (Ionides' monitor or Tanzanian black-throated monitor) is wild, not domesticated. Most traded animals were wild-caught; captive breeding is limited. People kill or hunt them, capture them for live trade, use meat and skins, sometimes for traditional medicine, and display them in zoos. Adults ~1.2–1.8 m; captive life ~15–20+ years.

Danger Level

High
  • Bite trauma: large adults have strong jaws and can cause deep lacerations/crush injuries; bites often require medical evaluation.
  • Lacerations from claws during restraint/handling; risk increases with stressed, wild-caught, or poorly socialized animals.
  • Tail-whip strikes can cause bruising/soft-tissue injury.
  • Infection risk from oral bacteria after bites/scratches; prompt wound cleaning and medical care are important.
  • Husbandry-related hazards: escaped large monitors can cause property damage, injure other pets, and create public-safety risks; secure enclosures are essential.
  • Behavioral risk profile: intelligent, food-motivated, and can be defensive; even well-kept individuals may react unpredictably during feeding, breeding season, or veterinary handling (general varanid behavior summarized in Bennett, 1998/2002; Pianka & King, 2004).

As a Pet

Not Suitable as Pet

Legality: Laws vary. In many places you can own a Black-throated Monitor (Varanus albigularis ionidesi) without a license, but some states/countries ban or require permits. Trade usually needs CITES Appendix II paperwork, so check local and export rules.

Care Level: Expert Only

Purchase Cost: $600 - $2,500
Lifetime Cost: $12,000 - $40,000

Economic Value

Uses:
International pet trade (live reptiles) Zoological/educational display Research/education (comparative physiology/behavior, herpetoculture) Skins/leather (at broader complex/genus level; localized and variable) Subsistence use (meat) in parts of range (broader complex) Traditional medicine/curio trade (localized; broader complex)
Products:
  • live animals for private keepers and collections
  • display animals for zoos/education programs
  • (localized/broader complex) meat
  • (localized/broader complex) skins/leather products
  • (localized) curios/traditional-medicine items

Relationships

Predators 8

Human
Human Homo sapiens
Martial eagle Polemaetus bellicosus
Tawny eagle Aquila rapax
Secretarybird Sagittarius serpentarius
African rock python
African rock python Python sebae
Nile crocodile
Nile crocodile Crocodylus niloticus
Spotted hyena Crocuta crocuta
Honey badger
Honey badger Mellivora capensis

Related Species 6

Cape white-throated monitor Varanus albigularis albigularis Shared Species
Angolan white-throated monitor Varanus albigularis microstictus Shared Species
Savannah monitor
Savannah monitor Varanus exanthematicus Shared Genus
Nile monitor
Nile monitor Varanus niloticus Shared Genus
Ornate monitor Varanus ornatus Shared Genus
Desert monitor Varanus griseus Shared Genus

The black-throat monitor is the second-longest lizard species in Africa and the largest in mass.

Black Throat Monitor Facts

  • The black-throat monitor is the heaviest in mass and second-longest lizard species in Africa in terms of length. They grow up to 7 feet in length and weigh over 60 pounds!
  • They are excellent climbers. They live in trees for most of their juvenile life.
  • Pet black-throat monitors are known to be very affectionate toward their owners. They even follow them around the house.
  • Black-throat monitors can break their own thyroid bone while attempting to fit whole prey in their mouths.
  • These lizards enjoy being taken out on leashed walks. Just don’t let them loose because they will likely climb up a tree and refuse to come back down.

Black Throat Monitor Summary

When it comes to mass, the black-throat monitors are the largest lizard species in Africa, and the second longest in length, second only to the Nile monitor. Their name comes from the patch of dark scales on their throat which differentiates them from the white-throat monitors. Unlike other monitor species, the black-throat isn’t a great swimmer. However, it makes up for it by being a fantastic climber.

Black Throat Monitor Scientific Name

The binomial classification of the black-throat monitor is Varanus albigularis, which is a group of rock monitors. It belongs to the genus Varanus, which is derived from the Arabic word waral meaning “warning.” The specific name, albigularis is a compound of two Latin words: albus which means “white” and gula which means “throat.” This species is called “black-throat” because of the dark scales that cover its throat.

The black-throat monitor is one of three subspecies of rock monitor lizards in Varanus albigularis. The other two subspecies are:

  • The white-throat monitor (Varanus albigularis albigularis) which is the nominate species
  • The Angolan white-throat monitor (Varanus albigularis angolensis)

The trinomial name of the black-throat monitor is Varanus albigularis microstictus. Although some taxonomists purport there to be four subspecies, with Varanus albigularis ionidesi being the fourth, other professionals believe there to be only three subspecies of rock monitors, with V. a. ionidesi being a description of the juvenile form of Varanus albigularis. V. a. microstictus is sometimes used interchangeably with Varanus albigularis ionidesi to classify the black-throat monitor.

These lizards are also called black-throated monitors. Both of these variations are acceptable and commonly used.

Varanus is the only genus of the family Varanidae that contains living species. Other monitor lizards that belong to this family are the komodo dragon, the Nile monitor, the Asian water monitor, and the ackie monitor.

Black Throat Monitor Appearance

Black-throat monitors are the second longest and largest monitor lizards in Africa. They are the largest of the four subspecies of rock monitors. Adult monitors grow to reach lengths of up to 7 feet in length and weigh over 60 pounds. The males are typically larger than the females. They are immense in size and, for this reason, are unpopular among the lizard-keeping community. To house them would require a great deal of space.

They are typically dark grayish-brown or tan and have yellowish or white markings to match the general color of their habitat. The mottled patterns of the markings and their color are different for each lizard. Sometimes, the markings fade as the lizard grows older, but they still remain visible. The markings are bigger on the back of the lizard and smaller around the leg and side regions of the body. Towards the tail, the markings form bands.

Black-throat monitors have an incredible defense system: serrated teeth, sharp claws, and long, powerful tails that they use as whips to protect themselves. They have short legs and a forked tongue and use it like a snake – flicking it to assess the scents around them.

Black threat monitor

Because these monitors are immense in size, housing them would require a great deal of space.

Behavior

They are great climbers. What they don’t accomplish with swimming is made up for by their ability to scale trees. Juvenile monitors spend most of their life in trees to stay safe. Since they are smaller in size when growing up, they are targets for predators on the ground. They live mostly in trees until they reach their full size in adulthood and can walk freely and securely on the ground. However, when they are threatened, they may still flee to the trees.

This type of monitor can be aggressive in the wild. When aggravated, these lizards hiss, puff up their bodies, lash out with their tails, claw, and bite with their painfully sharp teeth and powerful jaws.

Black-throat monitors are burrowing animals. In their natural habitat, they like to burrow underground and hide under rocks. In captivity, there should be enough space for them to dig underground and enough boulders and rocks for them to crawl under. These monitors are diurnal animals, which means they are active during the day, usually stalking their terrain to find food, and settling down to rest at night.

Captivity

When raised around people, they become docile. They are known to be a playful and active. They like to engage in regular activities like climbing and burrowing and are intelligent enough to recognize their owners and even follow them around. Although black-throat monitors can make loving pets, it is not advisable for beginner owners. They have needs and requirements that can only be handled by expert lizard keepers.

Even in captivity, these monitors need to associate with humans regularly or else they would grow aggressive toward people. An aggressive black-throat monitor should never be approached because its bite can inflict serious damage.

Monitors should not be kept with other pets. They are too large and do not usually get along with smaller animals. In fact, they might try to eat them. These reptiles live better alone.

Black Throat Monitor Habitat and Population

The black-throat monitor is native to Tanzania. It is predominantly found in the arid regions of east African countries such as Tanzania, Somalia, Burundi, Ethiopia, and Kenya. Its range does not pass the jungles of the Democratic Republic of the Congo and South Sudan.

They exist naturally in various habitats. They like to live in hot, arid regions such as savannas, prairies, and steppes. You won’t find these monitors in rainforests or true desert regions.

An excellent climber, they live in trees during their youth in order to remain safe from predators on the ground. Like all rock monitors, adult black-throats live in burrowed holes, typically beneath trees.

If you are looking to spot these big lizards in the water, you might be severely disappointed. One difference between this monitor and other monitor lizards such as the Asian water monitor is that they are not swimmers.

This subspecies is not currently listed on the IUCN Red List of Threatened Species. However, its nominate species, Varanus albigularis, is listed as Least Concern.

Reproduction and Lifespan

The reproductive process of the black-throat monitor starts at the beginning of the dry season. First, the male and female monitors usually dwell together to mate intermittently for days. The female requires plenty of food during the breeding season in order to lay her eggs. She lays the eggs in a pre-dug hole, often at the end of a termite nest, or in damp soil. This is done in order to make sure that the eggs stay at the correct temperature and humidity level.

The clutch size varies but they are known to be able to lay more than 30 eggs at once. The eggs hatch after 116-180 days during the rainy season, ensuring that the hatchlings have a survival advantage. The rainy season comes with bountiful food and water, optimal for newborn monitors.

Hatchlings grow rapidly and reach sexual maturity within two years. They reach adulthood at 6 feet in length and at least 60 pounds in weight.

Monitors in captivity live long lives when properly cared for. In fact, they have a lifespan of up to 25 years.

Diet

They are obligate carnivores, which means they do not digest plant material and get most or all of their nutrients from flesh. In the wild, adults prey on whole animals such as rodents, other reptiles, birds, and even insects. They are an opportunistic species so they will eat almost anything they can find. They eat carrion, or dead flesh, as well as hunt their own prey.

In captivity, they still require a robust range of prey animals. Black-throat monitors are typically fed lizards, snakes, large roaches, insects, chicks, crustaceans, and fish. Insects added to their diet should be brushed with calcium supplement powder because insects generally lack in this mineral. Mice are also one of the more popular whole-prey foods for these monitors.

They will readily eat cat and dog food, but owners should not make these a go-to dietary option as they do not contain the necessary nutrients required to sustain them. Also, canned and processed food have a high-calorie content which can cause obesity. A lot of effort goes into the feeding and upkeep of these large monitor lizards, so potential owners need to consider all of this before adopting one.

These creatures have slow metabolisms and do not need to be fed daily. Instead, they should be fed a few times a week. The frequency should depend on whether the lizard is slim or overweight, so it is strongly advised to keep a watchful eye on the size of your pet.

Cooked eggs with the shells are a great source of calcium for them, but they should be reserved as occasional treats because of their high cholesterol and fat levels.

Predators and Threats

Adults are very large and formidable animals, so it comes as no surprise that they do not have many natural enemies in the wild. However, they are prey to crocodiles, pythons, eagles, and leopards. Some humans also hunt these monitors for food.

Although black-throat monitors in captivity don’t usually have to worry about predators, that doesn’t mean they cannot suffer from other health-related threats. Pet monitor lizards are prone to metabolic bone disease (MBD), which is caused by an inadequate calcium intake. Lack of calcium to fortify the bones of the lizard causes the bones to become weak and fragile, leading to movement restriction and, eventually, death. Insects are a main source of food for these monitors, but they do not contain the proper amount of calcium for them. This is why brushing the insects with powdered calcium supplement before feeding them to monitors is strongly advised.

Another serious health issue that these reptiles in captivity can face is obesity. This comes as a result of excess feeding, and also from providing too much fatty foods such as eggs and rodents. They have very slow metabolisms, so do not need to be fed daily.

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Sources

  1. Wikipedia / Accessed November 3, 2022
  2. Biocyclopedia / Accessed November 3, 2022
Rose Okeke

About the Author

Rose Okeke

Hi! I am a writer, actor, and filmmaker. Reading is my favorite hobby. Watching old movies and taking short naps are a close second and third. I have been writing since childhood, with a vast collection of handwritten books sealed away in a duffel bag somewhere in my room. I love fiction, especially fantasy and adventure. I recently won the James Currey Prize 2022, so now, naturally, I feel like I own words. When I was 11, I wanted to be a marine biologist because I love animals, particularly dogs, cats, and owls. I also enjoy potatoes and chocolate in all their glorious forms.
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Black Throat Monitor FAQs (Frequently Asked Questions)

Black-throat monitors can be dangerous when threatened or provoked, especially in the wild. They have very sharp teeth and claws, and a powerful tail that they use as a whip. Although these animals are pretty chill when accustomed to people, they should still be handled properly by expert handlers.