T6s vs 77D autofocus

I haven't tested the M50 MKII with birds in flight or fast action, but the autofocus seems just as good as my Canon T7i (800D) cameras in that regard. For wildlife photography, the mirrorless cameras I have just seem a little bit too small. Other things about the mirrorless cameras are too small, like a person needs a little longer fingernails to operate the pad or buttons on the back or top. But I'm starting to get used to it; It's just quite a bit of a change.

If you really like to take photos of birds in flight I think the Canon 90D or Canon 7D MKII would be best from what I hear. But the Canon T7i (800D) camera that I have (I have three of them) works extremely well with the autofocus with nine center cross-type points. I suppose I should try the 45 autofocus points, but I just don't take enough pictures of birds in flight. I think it's because of where I take pictures, there's just so many trees around that block the view. I know of one reservoir that's good, but there's mostly geese there.

I'm now using the Canon T7i (800D) camera with the Tamron 150-600mm lens for bird photography. I bought three Canon T7i (800D) cameras which may seem excessive (and probably is), but that's because I'm just so happy with them. I got excellent prices for them on-line (body only), much better than I could at retail stores.

Then I had an idea to try mirrorless (bought two of them). That's been good too, but there's a big learning curve for that smaller camera. The last thing I discovered was to disable the camera from automatically changing to MF from AF, during one of my photo sessions (in the menu). There's other quirks too, like if you are planning to use the viewfinder and then chimp with the LCD screen, there's an annoying sensor that shuts off the LCD screen if you get too close (like for near sighted people). The workaround was to pull the LCD screen away from the body so that the forehead would not activate the sensor. The battery life is shorter too.

Rocket13 (who posts his birds-in-flight on the Show Your Snaps thread at times) does a fantastic job of capturing them with a Canon 90D and a Canon EF 100-400mm lens. He was using the Tamron 150-600mm lens but found that combination too heavy or difficult to use.  Rocket also was using a Tamron 100-400mm lens.

I think you would be ecstatic to use something like a Canon 80D, Canon 90D, 7D MK2, T7i (800D) or T8i (850D) camera. The autofocus locks on quite quickly. Check the reviews. Some people like the Canon M6 MKII, but there's no viewfinder, unless you buy a separate one to add on. I don't want to be negative about the M mirrorless systems, but I think they still need refinement until they reach the level of Canon crop DSLR cameras. I know very little about the R systems, except that they generally are more expensive and there's no crop factor for full frame.