You’re awakened at 3 am by strange sounds. Better still, you’re awakened by your spouse at 3 am, who was wakened a few moments earlier by strange sounds. Now, after trying to make sense of them in the dark, they’ve wakened you. Groggy, you listen to the bumps, scrapes, and thuds emanating from somewhere vaguely above you. Not small pitter-patter noises like a mouse would make. Probably not even like a rat would make. Unless it was a rodent of unusual size.
There is some disagreement between the two of you as to whether the noises are coming from above, the roof, or from outside your door. Your door that happens to open onto a semi-outdoors second floor patio. After a few more minutes of listening you decide the only thing to do is get up and go look. Your spouse is none to keen on this course of action and to be honest you’ve been more enthusiastic than this about courses of action in your life, but there doesn’t seem much else to be done.
There’s nothing amiss outside and you return to bed. The noises stop. Then a few minutes later they begin again.
What does the mental list you build look like, the mental list of all the potential critters native to your particular area that might be cavorting on your roof at 3 am? Once upon a time my list would have included the aforementioned rats and mice. Maybe cats. In some locales possums or raccoons, perhaps even a small wildcat or lynx. Birds of various sorts (unusually nocturnal ones at that). Bats maybe.
But you don’t live in a familiar locale. You’re in a new environment. A tropical, equatorial environment. What the heck do I include in my mental list? Monkeys? Other animals I don’t even know about. Slowly, the noises subside or else sleep overtakes us.
The next day in language class we describe our experience to our instructor. She nods and listens thoughtfully. I ask if there are monkeys in the city. I haven’t seen any, but who knows? She doesn’t directly answer my question, but has a ready line of alternate thought and a word to go with it – biawat.
There are a variety of lizard species native to Sumatra. Biawat is just one of them. One of the bigger ones. This one:

If that looks like a biz lizard, it’s because it is. Or at least can be. Typically they grow to about 6′ long and up to 40 lbs. They can also be much larger. And according to our teacher, it is not at all uncommon for them to end up on rooftops after hunting and killing chickens, which they are quite fond of eating.
How comforting.
We might be less freaked out, but our classmate the next day described an encounter with one of these rather large lizards on a street in the city near a car he was trying to get into. Huge. Intimidating. And our classmate shared a couple of months back how he really likes reptiles in general. But he was still freaked out by seeing this creature.
So, maybe that’s what was on our roof the other night. Comforting in that it doesn’t appear to be an infestation of any kind (this was the first time we’d ever heard such noises in this house). Less comforting in that it may not be as uncommon as we’d like (the people house-sitting for us while we were in the US in July indicated they heard strange noises at least once while we were gone). So long as they stay on the roof proper and don’t get into any sort of attic or crawl space where they might fall through the ceiling into our room, there isn’t much I’m inclined to do about it – or actually can do about it.
But it makes falling asleep these past few nights just a tad less comforting than before!