I saw a monitor on a Kithul tree today

I saw a monitor on a Kithul  tree today 

I saw a monitor, a small one on a kithul  tree today. It was sun bathing on a midrib of a leaf close to the leaf base. An unusual place because it was on the top of the tree that is about 20 feet tall. I didn’t know that monitors are arboreal; can climb trees until I saw this. 
Monitors were part of the daily life of rice  farmers those days when we were growing up. That is because monitors eat rice field crabs and rice field crabs are one of the foremost enemies of the rice farmers especially in mountainous region. I remember we were told that monitor is considered a friend of rice farmer because of this eating habits of it and it is sort of protected animal because of that but I am not too sure about that now.
Rice crabs are a menace those days because they used to make tunnels on the weirs between rice fields thereby making it difficult for the farmers to retain water in the fields.
So every morning somebody, mostly the young son of the family, has to walk on each weir to see whether crabs have dug up tunnels and if they have, to block them by stepping on the mouth of the tunnel and push it until it is squarely blocked. If it is big one he has to bring some clay from edge of the field and fill the hole before pushing the clay with the sole until the tunnel is completely sealed. 
I think the crabs saved themselves from Monitors; very active and strong and robust carnivorous , by digging  in to  narrow tunnels where monitors cannot access. And the tunnels were like a maze, the entrance from the upper field to the exit in the lower one would be meters away from one another.
But when we were growing up, in a certain era ,rice crabs were annihilated, within a very short period of time , and I wouldn’t think  a single crab can be found , as the villages used to say ‘even for medicinal purpose’ in where we live, although the extent of rice fields have not diminished in size at all.
The cause for total annihilation was introduction of pesticide and weedicide in the rice farming. It made rice farming much economical and efficient. Crab holes in the weirs became a thing in the past, and with them monitors also disappeared, either because they were also poisoned being on the higher plane of the food chain or because they lost their staple food source.
This is why seeing a monitor on a Kithul tree was unusual today. 
Monitors in other countries have different uses. They are kept as pets by people who like reptiles. In fact Monitors have become a staple in the reptile pet trade. The most commonly kept monitors apparently are the savannah monitor and Ackies monitor; due to their relatively small size,low cost and relatively calm disposition.
Other uses of monitors for people  include medicinal purposes; in some parts of Pakistan their flesh is eaten for the relief of rheumatic pain and abdominal fat is used as salve for skin infection. In South India and Malaysia monitors tongue and liver is eaten as an aphrodisiac it seems. They must be already extinct in their, I suppose. 
Here , other than being formerly of rice growers friend, monitors I have never heard of being of any use to us except for, in this report written by a British civil Officer Mr Morris during British period as included in Teenent’s natural history.
‘The skillfulness of the Singhalese in their preparation of poisons, and their addiction to using them, are unfortunately notorious traits in the character of the rural population. Amongst these preparations, the one which above all others excites the utmost dread, from the number of murders attributed to its agency, is the potent kabara – tel.’
He goes on ‘In the preparation of this mysterious compound, the unfortunate Kabara – goya is forced to take a painfully prominent part. The receipt, as written down by a Kandyan, was sent to me from Kornegalle, by Mr. Morris, the civil officer of that district; and in dramatic arrangement it far outdoes the cauldron of Macbeth’s witches. The ingredients are extracted from venomous snakes, the cobra de capello, the Carawilla, and the Tic – polonga, by making incisions in the head of these reptiles and suspending them over a chattie to collect the poison as it flows. To this, arsenic and other drugs are added, and the whole is “boiled in a human skull, with the aid of the three Kabara – goyas, which are tied on three sides of the fire, with their heads directed towards it, and tormented by whips to make them hiss, so that the fire may blaze. The froth from their lips is then added to the boiling mixture, and so soon as an oily scum rises to the surface, the kabara – tel is complete.”
I don’t think there is a poison as potent as this anywhere in the world!