Black-headed monitor facts for kids
Quick facts for kids Black-headed monitor |
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| Freckled monitor (V. t. orientalis) | |
| Conservation status | |
| Scientific classification | |
| Genus: |
Varanus
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| Species: |
tristis
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The black-headed monitor or black-tailed monitor (Varanus tristis) is a type of monitor lizard found in Australia. It is a relatively small lizard. People sometimes call it the mournful monitor, freckled monitor (Varanus tristis orientalis), or the racehorse monitor. It shares the "racehorse" name with the Gould's monitor because they are both very fast!
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What's in a Name?
The scientific name for this lizard is Varanus tristis. The word tristis comes from Latin and means "sad." This name was chosen because some of these monitors, especially those living around Perth, are completely black. Their dark color might have seemed "sad" to the person who named them.
Where Do Black-Headed Monitors Live?
This monitor lizard lives all over mainland Australia. It is the most widespread monitor species there. You can even find it on some northern islands, like Magnetic Island. However, it does not live in the very southernmost or south-easternmost parts of Australia.
There are two main types, called subspecies:
- V. t. tristis mostly lives in western Australia.
- V. t. orientalis is found mainly in eastern Australia.
Sometimes, both types can be found in the same areas, such as along the east coast of Queensland. These lizards often live near rivers in forests, scrublands, and woodlands. They can also be found in deserts. They like to hide in tight spots, such as loose tree bark, hollow trees, or cracks in rocks.
What Do They Look Like?
The black-headed monitor can grow to different sizes depending on its type.
- The V. t. tristis subspecies can grow up to 80 cm (about 31 inches) long. This makes it the larger of the two types. Monitors from Perth are completely black. But those living further north, in warmer places, tend to be lighter in color.
- The freckled monitor (V. t. orientalis) is smaller, growing up to 60 cm (about 24 inches) long. It has lighter, more distinct colors and a tail that is less spiny.
Baby monitors of both types are brightly colored. However, only the freckled monitors keep much of their bright colors as they grow into adults.
Telling Males from Females
You can usually tell male monitors apart once they are about two years old. Males have a large group of spiny scales on either side of their vent (a small opening on their underside). Female monitors do not have these obvious spines. They might have only a few small spines that are not much bigger than their other scales. Both male and female monitors can start having babies when they are about 20 cm (8 inches) long from their snout to their vent.
How Do They Behave?
Black-headed monitors are most active during spring. They might travel up to a kilometer (about half a mile) each day looking for food. They need to eat a lot to build up fat reserves. These fat reserves help them survive the 6-7 cold winter months when they become less active.
Both types of monitors like to climb trees, but V. t. tristis spends a little less time in trees than V. t. orientalis. Sometimes, when a black-headed monitor walks or basks in the sun, it curls its tail over its head and body. Scientists are not sure why they do this.
What Do They Eat?
V. tristis eats a variety of small animals. Their diet includes:
- Small mammals
- Frogs
- Other lizards, such as agamids, geckos, skinks, and even smaller monitor species. They can even eat thorny devils!
- Bird eggs and chicks from nests
- Many kinds of insects, like grasshoppers, beetles, ants, and stick insects.
What they eat most often can change depending on where they live. For example, some populations might eat more lizards, while others might eat more insects.
How Do They Reproduce?
The breeding season for black-headed monitors is in November. During this time, male and female pairs start sharing the same tree. Females lay a clutch of eggs in December. A clutch usually has 6 to 11 eggs, but sometimes there can be as many as 17! These eggs hatch in February or March. They need to be kept at a temperature of 27-29 degrees Celsius (80-84 degrees Fahrenheit) to hatch properly.
