This may be a long stretch to id, but thought I'd try it out anyway.
I've been refamiliarising myself with a few of the basic more common birds a lot since returning to HK and as I'm staying in Central for just a couple more weeks have been spending a lot of time in the Zoological & Botanical Gardens.
On several occassions I've seen an insect eating (micro) bat flying during the day. Each time I've seen it I've got great views, but haven't had my camera on me to take any shots. From what I've seen it certainly looks like a long-eared variety. It's flying around just above the tree line, over and around a break in the trees and sort of looks to be pale brown, even blonde-ish.
If someone has any clue about what bats may be roosting in Central, then I could maybe have a look at some pictures online. I do have a bat detector on it's way, but that arrives mid-late feb and I doubt this little chap will be day flying for that long.