What bird would be active at night?

Hello, 

Probably the most bizarre thing just occurred to me tonight, I was so surprised. 

I walked to my back door and what I thought was a massive moth flew from my backdoor onto my shed about a meter away. Only until I saw it properly did it realise it was a dunnock/small brown bird. I didn’t realise birds would be active at this time (except for the obvious nocturnal birds), so it surprised me.

Is this more likely to be a bird or a bat?

It looked very similar to the juvenile dunnocks present in my garden, would this be? 

Thanks