Foreign visitor? A challenge to identify...

Can anyone identify this call? I’ve never heard anything like it in the UK.

It’s a lovely sound, but I’m concerned for its survival if non  native.

Justin, Hampshire

It sounds a bit like a contact call that many birds make at this time of year but I'm afraid it's not one I recognise.
There's also a couple of "tchk, tchk" calls. Not sure whether that's a different bird or not.
Have you got a longer recording as a 3 second clip is not much to go on.

We live in a row home and the house attached to ours is vacant. It's been on the market since before we moved in, and nobody's lived in it for at least 7 years. There was a small cast iron fence between the two yards (on my property line) that went from under the fire escape to the brick garage (which you can see in the image). I removed that fence as it was on my property about a month ago and installed brand new, beautiful sod.