Loud bird at night?

Question

I was visiting a friend in the west San Fernando valley about 20 miles NW of downtown LA. I noticed a bird chirping loudly in the tree in his yard as I was leaving around 10:30 p.m. I commented to him and he told me that the bird was doing the same thing last night all night, but it wasn't there the night before. Also, neither of us can remember ever hearing a bird chirping like that in the middle of the night in our area. It was a high pitched chirp (sounded like a small bird). I'm sure it was just a single bird.

What might that have been? A specific exotic kind of bird? I've heard that we have many different kinds of feral parrots and such around here now and I've heard they can be active at night, but I've never seen one here yet. Or could it have been a more ordinary bird in our area trying to mate or something?

It's been unusually hot at night here the last week or so as well (lows in the 70s and 80s), so perhaps that provides a clue?

Answer 1

Mocking birds commonly call at night especially where there is artificial lighting (parking lots, etc).

Answer 2

....?

Answer 3

Northern Mockingbird is correct.

Answer 4

I live in SoCal and have heard Northern Mockingbirds chirping late into the night.  They can sound like any other bird or car alarms and other things and they are really loud for a small bird.