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Rhaldi Road heron Maseke


Dragons of Klaserie

Posted 8.02.2015Comments • You are here: Ranger Diary » General
Dragons of Klaserie
Monitor Lizards do look vaguely draconic it must be said, but they share more than scales and morphology with the ancient lizards and dinosaurs. Monitors breath like dinosaurs did and the way modern birds do. This adaptation in birds allows them to fly at high altitudes where the oxygen is thin and similarly facilitated respiration in Dinosaurs during the Triassic period when the oxygen level in the atmosphere was around 12% and not the 21% we know today. This “unidirectional” method of breathing extracts oxygen from the air while inhaling AND exhaling. This may simply be a “throwback“ from common ancestry but it has benefitted the monitors in their current niche in the ecosystem.
The two different monitors we get in Klaserie- Water and Rock Monitors are both well adapted to their respective niches. The Water Monitor; Varanus niloticus, at 2 meters in size, is Africa’s largest lizard. With a slender streamlined body and long latterly flattened tail, water monitors have a varied menu and will eat almost anything available in their aquatic habitat as well as birds, mammals, reptiles and even carrion. They are a formidable predator of crocodile eggs and have perfected the habit of locating the nests and consuming eggs and hatchlings. The prey is mostly swallowed whole when the powerful jaws become unhinged while larger prey can be dismembered. Water monitors can stay submerged for extended periods, close to an hour.
By contrast the Rock Monitor- Varanus albiularis is most at home on the ground or in trees. Both species have long strong claws adapted to climbing and digging. Rock monitors have a heavier build and move about on the ground extensively. They may seasonally nest in elongated tree cavities that are filled with dead grass. This nest is also used for courtship purposes. Male rock monitors have territories that they actively defend with wrestling matches. Monitors threatened by predators are fearless and stand tall on straightened limbs distending the body, throat puffed out, mouth wide open while emitting loud hissing sounds. The tail is thrashed from side to side and the bite is powerful and steadfast, while the strong curved claws will rake the aggressor. Rock Monitors are also known to feign death –a defence mechanism called thanatosis. Aggressors such as dogs may believe the lizard is dead and loose interest.
With each of the monitors adapted to a specific habitat, their prey has a degree of overlap and some specifics. To locate potential prey they use eye sight and also rely on taste and smell. Monitors have a bifurcated or forked tongue that flickers in the air collecting scent chemicals which are then delivered to the Jacksons Organ positioned on the roof of the mouth. The Jacobson’s ’Organ has two receptors or lobes, one for each fork of the tongue. The organ detects differences in the concentration of scent so the monitor is able to find a direction and the scent trail of the quarry. Water monitors can even “smell “underwater. Both species possess distinct ear holes.
Being reptiles, monitor lizards are poikilothermic or cold blooded and are most active after warming their muscles in the sun. They mate in early spring. The eggs of the water monitor are often deposited within an active termite mound that maintains a constant temperature aiding in the incubation of the eggs. The incubation period may be up to a year and is thought to be temperature related. The tiny hatchlings emerge after the rains when the soil is soft or the mother may return to open the nest and release them. This is a fascinating thought, something as primitive as this lizard, having a built- in clock that will send her back, to a nest and eggs laid up to a year ago! After the hatchlings emerge, they receive no maternal care. Monitors are thought to live till about 10-15 years and become sexually mature at 3-4 years old. A relic of the ancient lizards they may be, nevertheless they have adapted brilliantly to the modern world and I am told by our visitors that they are found on many continents across the world.

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