By spiders. The frigging spiders are driving me crazy. I guess the IR lights attracts them at night and they decide it is gonna be cool to weave web in front of the camera. The good news is that the camera does not see the web, the bad news is that the camera does see the frigging bug pottering all over the damn place and that trigger alerts.
I have covered the lens and sprayed repellant on the camera, but it seems not to affect them.