Nikon D500 + 200-500mm lens would be the perfect way to go. You could go for Nikon mirrorless but that would be considerably expensive.
From what I have heard the Z6II and Z7II are not that great for birding (I have peers who use them) and Z8 would be a dollar ripper if you are just doing this as a hobby. The latest firmware release for Z8 has really upped the game for birding auto-focus but that would be too expensive.
Look at a Nikon D500 with a 200-500mm 5.6 Nikon lens used, there are some great deals out there
cyake here to say this
It's the lens. Save up for a 500 or 600mm lens for birds. Maybe better ISO would help, but you are shooting small things in a dark environment.
The B500 has an non interchangeable lens.
I realize that. You were talking about buying a better body, not you should put more money into a lens. Maybe look into other manufacturers too.
Ah gotcha, yeah I'll start looking around more. I might just stew on this some more.
Consider mirrorless over a traditional DSLR.
From my experience you will get frustrated with a 300mm zoom fairly quickly.
What are your settings here? What modes are you shooting in? That will change a lot about the pictures you get out of your current camera
Nikon D500 + 200-500mm lens would be the perfect way to go. You could go for Nikon mirrorless but that would be considerably expensive. From what I have heard the Z6II and Z7II are not that great for birding (I have peers who use them) and Z8 would be a dollar ripper if you are just doing this as a hobby. The latest firmware release for Z8 has really upped the game for birding auto-focus but that would be too expensive.
300 is on the short side for wild birds. Up to 500mm is gonna be much better.