Reminds me... I procurred a PoE camera to go on an as yet, not manufactured/constructed bird table. This is in an IP rated enclosure. Not only that, but it has IR emitters to in theory capture night visitors too.
I was going to configure it with the NVR that was already running the CCTV cameras on the front of the house - I had
Shinobi running as the NVR and that could handle motion detection etc..
Sadly, the hypervisor running the NVR has not been switched on since energy prices more than doubled - but I imagine a half decent Pi could handle a feed from a single CCTV camera.
The only thing I'd mention is that any type of CCTV that has any persistence is fairly IO intensive and I can't imagine that a micro-SD card in a RasbPi would stand up to it for that long. An external USB HDD or a network share backed by spinning disks would probably be the best place for storing the videos.