G_N

Here are a couple taken with my new X-T5 (new body) and 100-400 (used lens!). I'm still getting used to the camera, but so far so good. Thanks.

Here's another Robin.

Here are a couple taken with my new X-T5 (new body) and 100-400 (used lens!). I'm still getting used to the camera, but so far so good. Thanks.

Here's another Robin.

Here's another Robin.

Sorry, fat finger.  Meant AF-C - auto focus continuous

Two days old.

Here are a couple taken with my new X-T5 (new body) and 100-400 (used lens!). I'm still getting used to the camera, but so far so good. Thanks.

Here's another Robin.

X-H2S, XF100-400+TC1.4x - Reed Warbler

X-T4; Fujinon XF150-600mmF5.6-8 R LM OIS WR; 1/2000; f7.1; ISO640; 500mm; hand held...
 

Female Belted Kingfisher Waldport, OR. X-H2s, Fuji 150-600.
 

1) I'm no expert at the focus modes but I believe "bird" is just a fine tune to help it track birds.  I would still expect you would need ASPC to track a moving bird.
3) Keep in mind that Image Stabilization is for camera movement only, not subject movement.  I would use to help steady your motions but you still need the appropriate shutter speed to get the motion blur or not that you want.

1) The subject detection options will attempt to detect the shape of the subject (such as bird) - it doesn't matter what the bird is doing - although it finds it easier if there is good light and it can see an obvious bird head or eye.
It will fallback to your AF Mode if it doesn't detect the subject.
You can't select a Photometry option when Subject Detection is set.
2) Some of these are switches (like Subject Detection) which applies the action immediately and some take you to menu (like AF Mode)
3) I tend to leave OIS on in Shooting Only mode all the time but some think you should turn it off for high shutter speeds