Why are monkeys here?

Two monkey was spotted hanging around Toa Payoh Lor 1.

One afternoon last month I was walking home with my wife to our block on Montreal Drive in Sembawang when we were surprised to see two monkeys. One of them was eating a banana.

My wife was worried that the monkeys may climb into the flats, especially those on the lower floors, through open windows.

I have never seen a monkey in the estate before in the 12 years that I have lived here, though I had heard of an earlier sighting.

Why are monkeys appearing in our estate?

Is it because we are building too many housing blocks in what used to be their natural habitat?