Tag Archives: urbanecology

Common Indian Monitor (Varanus bengalensis)

Monitor lizards include some of the largest of their kind on Earth with 70 or more species spread around the globe. In India, we have the common Indian monitor or Bengal monitor, yellow monitor, water monitor and Thar desert monitor.

DISTRIBUTION: Common Indian or Bengal Monitor (Varanus bengalensis) can be encountered across the Indian sub-continent and thrive in lower elevations, be it moist forests or semi-arid deserts.

As the most widely distributed of varanid lizards, their global range extends to west and south-east Asia; from the riverine valleys of Iran to Afghanistan, Nepal, Sri Lanka, Bangladesh, Burma and Indonesia. The clouded monitor is considered a sub-species of the common Indian monitor.

HABITAT: They dig soil to create burrows that are used as shelters along rock crevices and buildings. Common Indian monitors are not territorial and are constantly exploring new range in response to food availability and the seasons.

BIOLOGY: Monitors wear a dark studded, leathery hide stretched from snout to tail, around 100 cms is the average length of a Bengal monitor. They constantly flick a forked tongue, much like their serpent relatives, employed as a sensory organ rather than to swallow food. They store fat as reserves especially in their powerful tail that can grow up to 100 cms, a good source in times of prey scarcity.

Sub-adults are comparatively more colourful with cross bars across their throat, neck and belly; colouration has been observed to vary across the range.

Monitors are fantastic swimmers, reptiles with the highest standard metabolic rate, capable of submerging themselves for a whopping 17 minutes.

One of Into the Wild’s camera traps caught a common Indian monitor cooling off in a rock pool set in his natural habitat in Magadi. Click the forward arrow really fast to watch a stop motion of this rare footage:

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Read more about these active lizards:

http://www.scientificamerican.com/article/monitor-lizards-found-to-breathe-birds/

BEHAVIOR: Being diurnal, they sleep during the night and begin their day with a good bask at around 6a.m. These shy lizards avoid humans to every possible extent and are known to be solitary by nature. Though certain varanids are known to possess a small amount of venom, the Bengal monitor makes no claims to such toxicity; even when caught, they rarely bite.

BREEDING: Their breeding season is between June and September with male combat emerging as early as April.

FEEDING: A regular meal for a common Indian monitor could mean eggs, arthopods, snails, ants, beetles, grubs, among invertebrates. They are also known to feast on vertebrates such as fish, frogs, lizards and snakes but rarely. Even rarer is their scavenging of dead carcass.

Monitor lizards in India are significant beyond their natural history. Legend has it that Tanaji Malusare, one of Shivaji’s commanders, used Yeshwanthi (his monitor lizard) and rope to scale a rock face and launch an attack on his enemy, winning the Battle of Sinhagad in 1670.

Read more about how illegal trade of monitor lizard meat has entered the urban market here: http://wp.me/p5P9Ju-L

Chameleons

As many as 180 species of chameleon camouflage themselves in varying habitats across the world. The evolutionary adaptations of this old world lizard is fascinating, a genuine testament to the millions of years Nature has invested on its spectacular design and functioning.

DISTRIBUTION: Found primarily on the mainland of sub-Saharan Africa, roughly 50% of all chameleon species exist in Madagascar. They are also native to southern Europe, north Africa, middle east, Sri Lanka, southern India and select islands of the western Indian Ocean.

As a favourite of the pet market, this gentle reptile has emerged as an invasive species in parts of the United States (Florida, Hawaii, California).

HABITAT: Chameleons are almost always found in warm habitats inhabiting every kind of tropical rainforest, savanna available; also seen in desert and steppe.

BIOLOGY: Best known for their ability to change colour, the chameleon’s locomotion is characterised by swaying gait. They have heavily ornamented faces (especially in males) sporting crests, horns, nasal protrusions or a distinctly shaped head. Their eyes are independently mobile but co-ordinate when focusing on prey. The upper and lower eyelids of a chameleon are fused with a tiny pinhole through which their retinas observe the world in 360 degrees.

Mostly arboreal, a prehensile tail enables them to cling onto wiry tree branches as tong-like limbs carry them forward in a manner so theatrical and distinct unto chameleons. A long, slender highly modified tongue is rolled up when not in use and launched to catch prey.

The very anatomy of the chameleon is adapted for climbing and visual hunting.

MASTER OF DISGUISE: Chameleons the world over are capable of varying combinations of colour as striking as turquoise, yellow or purple. This ability functions as camouflage, social signal and to regulate temperature observed in some cases. The darker colours are reserved for agitation or intimidation; males show multicoloured patterns during courtship. This amazing ability to change colour is employed by some, like the Smith’s dwarf chameleon, in accordance to the quality of vision of different predator species.

How do they do it?

Specialised cells called chromatophores contain colour pigments present in the cytoplasm three layers below a chameleon’s transparent outer skin. The first layer is yellow + red; second is blue or white and the third melanin, a dark pigment that controls how much light is reflected. The colour pigment in each layer rapidly distributes and re-distributes to influence the animal’s colour.

FEEDING: Insectivorous, ballistically project their muscular tongue to capture prey at a distance. A chameleon’s tongue to body ratio is 1 : 1.5 or 2 on an average and temperature heavily influences the amount of food it consumes.

More on the chameleon:

https://www.youtube.com/watch?v=H2ACbO6HEq8