Night birds id

[Gykerthing]

I was in the car park of the Hartlepool Historic Quay last night at about 11.30pm Two birds were flying around the white lights they have there. At first I thought they were owls,  but they looked like small seabirds. Very hard to observe, but they seemed to be dark mottled, about the size of a pigeon, but slimmer. I can't imagine they would be catching insects, and I couldn't see any moths. Any suggestions?

[IanF]

Possibly bats instead of birds? Some are quite large.

[Gykerthing]

Thanks for your reply. I've been looking at bats and haven't found any that match...but it seems more likely. If only I'd been able to take a photo!