NVR is Network Video Recorder. It's similar to a DVR (Digital Video Recorder) camera system which is what you typically see at a 7-eleven or some other stop-n-rob type joint. Both record video for later viewing. DVR transmits an analog signal, over coax cable, directly to a DVR unit which in turn does the H.264 compression/conversion and stores the video. OTOH, IP cameras run over your standard Cat5 ethernet cable, are fully compatible with your LAN and do the H.264 conversion right at the camera sending the feed either directly to an NVR unit, or through your LAN/WAN whatever. They seem more versatile to me. I won't even consider a DVR unit if someone gave me one for free. I'm sure there are good uses for them I'm just hell bent on an IP camera so no DVR for me.
Based on what you wrote, the only camera that I can think of that fits what you want is the Arlo camera. They are wireless - completely - running on batteries. I tried some out in my outdoor aviary and I could not make out my Jardines and Caique from the surroundings half the time. But it sounds like you are more wanting a perimeter surveillance? Not something to watch the birds? If you use something that gives motion alerts inside the aviary I can imagine it would be going off non-stop. I can't recall if the Arlo required a subscription for alerts or if you got a certain amount of cloud storage and alert for free.
I'm highly adverse to any kind of subscription service for my cameras. I'm probably going to setup a BlueIris system and run my own server. I'm ordering my cameras this weekend once I crawl up in the roof and see how the heck Im' going to run cabling to the soffits.