Can Ai Servo cause blurry perched bird shots?

I shoot a lot of Birds in Flight, but I also try and use it for perched birds as well with varying results. Yesterday I was shooting some perched Red belly and Downy Woodpeckers and most of the shots came out just slightly out of focus.
I was using a 1DMKIV and 100-400V2. Granted I was shooting at 800 ISO and 1/800 shutter speed at 6.3 aperture so I thought maybe too slow a shutter speed, but I think its more the AI Servo setting.
Is my thinking wrong here ?

I have had issues in the past when i've gone from shooting race cars in motion (panning) w/ai servo then off to stationary subjects with ai servo. I typically switch to One Shot for still things. Works better for me.

Bsmooth wrote in post #18546540
Can Ai Servo cause blurry perched bird shots?

I don't know if it can ..... but I do know that in all of my experience it hasn't.

I have my cameras set to AI Servo at all times, and never change to another mode for any reason.

And I have my lenses set to I.S. Mode 1 at all times, and never change it for any reason.

When I focus on a perched bird - or any other stationary subject - focus is always spot-on. . I mean, the camera/lens always focuses where I tell it to. . Now, I don't always tell it to focus on precisely the right spot, because of the "imperfect human factor". . But that is another matter altogether.

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