Neither R6, nor R5...

Wait until the end of this month, when Canon is expected to announce the R7 and get on the list to buy one.

Strong rumors say the R7 will have:

Dual Pixel CMOS AF
32.5mp APS-C
15 fps mechanical, 30 fps electronic shutter
2x SD UHS-II memory card slots
4K @ 60/50fps (NTSC/PAL)
1080p @ 120/100fps (NTSC/PAL)
C-Log 3/HDR PQ
In-Body Image Stabilization

People are guessing at the price... many think it will be between $2000 and $2500. (The 7D Mark II sold for $1800 in 2014 when it was introduced.)

So that's about the price of an R6, but with much higher resolution. In fact, the R7 will have higher resolution than the R5 and your 5D Mark IV. This is because of the APS-C format sensor and will be ideal for wildlife photography... especially smaller subjects. It's like getting a "free 1.6X teleconverter" built right into the camera. Where you have an effective 560mm f/5 with your 100-400mm + 1.4X teleconverter now.... get one of the EF to RF adapters, put that lens/TC combo on the R7 and you'll have equivalent of "896mm f/8" on any of the full frame cameras. Or you can use your 100-400mm lens without the teleconverter and have an effective "640mm f/5.6". That's more "reach" than you have now, fitting a TC to the lens on full frame... It's also one stop more light and stronger background blur effects, f/5.6 instead of the effective f/8 you end up with the TC on the lens.

Alternatively you can crop images from any of the full frame cameras for similar effect.

However...

About 11MP remains after you crop 5D Mark IV's 30MP image down to APS-C size.
Or about 7.6MP remains when you crop an R6's 20MP image down to APS-C size.
Or about 17MP remains if you crop an R5's 45MP image down to APS-C size.

Or you can have 32.5MP images from an R7, already APS-C size (no cropping).

In addition to that, we can expect the R7 to have many of the autofocus features of the R5 and R6, though probably not quite as much as the R3.

Most folks think it will be similar size, weight and control layout as R5 and R6. It might even share the BG-R10 grip those cameras use.

True. Yesterday on a walk in the park I saw Canada geese, mallards, squirrels, pigeons, a turtle and some rather interesting humans lurking about. Someone mentioned the difference between birds in the wild and birds in the city. The honkers will allow you to walk within two or three feet of them here in the city. You could literally snatch one by the neck if you were so inclined. When I go to the wetlands preserves it's hard to get within 100 yards of the geese and ducks if they see you coming. Sometimes just the sound of the car wheels on the gravel is enough to startle them.

A final word: Thanks to you Rick and to Gene for this clinic on wildlife photography. There's a lot of absorb here. Patience, preparation, understanding your "prey". One thing a lot of us could pick up on is how little you guys talk about gear. Of course good equipment and software technique makes a difference but most of what talk about here that's useful to someone like me is the three things I mentioned above. Patience, preparation, and understanding.

I shoot a lot of eagles, and manual exposure setting without auto ISO is probably my most reliable combination. Using too large a spot kinda defeats the purpose. I am accustomed to 1° hand held spotmeters. The 4mm spot corresponds to something a little larger, but easy enough to work with.

_DSC2837 by Gene Lugo, on Flickr

_DSC1307 by Gene Lugo, on Flickr

_DSC2264 by Gene Lugo, on Flickr