a strange sound?

Ok, i'm up at 5 something in the morning right now.

That is NOT my usual time regarding waking up in the morning. I was up because i gotta pee. After that i couldn't go back to sleep so i decided to just stay up.

I went down to surf the internet instead.

And something weird happened.

Suddenly, i heard this unusual sounds of a bird imitation from some kind of a machine, only faster in speed and definitely louder coming from outside. You can tell it was NOT a sound of a bird, and it was more towards a sound of a machine or a bird machine instead. It was a strange sound.

I bend over to the window and when i'd moved the curtains to see where the sound come from, the sound abruptly stops.

ABRUPTLY. a real bird doesn't stop singing that way. a machine does, when it was suddenly turned off.

Ok, then i continued surfing the net. a few minutes later i heard the same sound again. this time i manage to look out through the window but i couldn't find anything that could relate to the sound in logical sense.

Ans again, the sound would suddenly stopped abruptly.

This continued for about an hour.

And in my mind, my first impression towards the strange sound was "aliens."

p/s: i watched & read too many sci-fi stuff. but i didnt lie about the strange sound.