Why isn’t AF picking up these birds?

Texchappy wrote:

Got my R6 today and tried to get it set up. First with the 24-105l and this one with the RF100-400, the AF just isn’t finding these birds. What am I doing wrong?

It kept locking on the fence. Earlier when I was using the shorter lens, it kept locking on a lawn chair in the corner.

Those birds are very small in frame and are viewed at the dimmest part of your lens' focal length... however, the R6 has a very sensitive -6.5EV which can isolate and track a bird's eye - It usually does this by locating movement as well since the R6 uses an A.I. program to seek out your targets... but there's ways to prompt your camera into looking harder for the eyes. The issue with some species of birds is that the heads look like tail feathers to the camera (especially IBIS)... and the camera actually looks for eyeball reflections, something I have observed when photographing scale models with people in them. You can test the AF on your television if there are people or animals on the screen or your home computer by bringing up subjects that you might otherwise photograph, and the camera will identify those as if they were live subjects in front of you.
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Low contrast (overcast) weather and also the reduced contrast of a lens that is at a high focal length will combine to make it harder for your camera to spot the eyes of birds.  The two sparrows appear to be male and female and the one on the left has its eye hidden inside a dark stripe... and the other has a visible eye (on the right) but it's very small in frame.  If you program your camera to actively hunt for an eye with the press of a button you should have much more success (see videos).
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Take a look at these TWO videos and you'll see how to set up your camera. My own R6 is set up in a similar way. You can also switch the Expanded AF Area and then make sure that Animal Eye Detect AF is selected. I've set this up on my C1 setting on my Control Dial. I've set C2 to Human and C3 to Vehicle tracking for convenience and it works.
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Watch the videos in the order I've posted them. I programmed my own R6 before these showed up online so I've used a slight variation of these options. But if you haven't done this you may struggle to have any of the camera perform as well as it can. Let me know if it helps.
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