I have heard of a few reports of night flying hummingbirds but most of the reports I get are of Sphinx Moths. I get a lot of reports of multiple, very little, brown, hummingbirds that feed just after dark or just before dawn that are always moths. I always advise the reporters to look very closely at the "bird" and make sure it has a straight bill, feathered tail, and no antennae. They appear in very limited light and feed like a hummingbird so they are often mistaken for birds. That said, anything is possible.

I get a number of different species of sphinx moths here in Valrico (20 miles east of Tampa). I've got a link on my Webpage called Spinx Moth - Hummingbirds Wannabes with a couple of pictures.

Here is a link that might be useful: Sphinx Moths - Hummingbird Wannabes