'Strange' Blackbird behavior

Hi all,

So I've been sitting at my computer and looked outside my window and saw a blackbird just sat in my garden like it's looking at something in a bush (as a cat would do scoping something out).
It was laying there for quite some time, I kept looking out for about 20 minutes to see if it was still there.. Still not moved.

I thought it might have been injured so I attempted to go and check on it, when I opened the back door it flew off seemingly absolutely fine.

5 minutes later, it appears again in the exact same position.

Does anybody have an explanation?

Thank you