I have enjoyed this forum for about a year now and value the experience and advice shared by its contributors.
I shoot in RAW and mostly in Manual mode to capture wildlife images but my first impulse is to shoot in Automatic mode so I don't miss the shot.
My concern is that the Elk might run or the Eagle might fly before a get a shot of it. Once I get a shot, I switch to Manual mode to refine my shutter speed, aperture or ISO knowing that, since I shoot in RAW, I can fine tune it in post.
Many of my final "keepers" are shots I took in Auto.
Does anyone else use this practice or am I just being an insecure "rookie"?

Jerry, you might try the (P)rofessional mode that is nothing other than the camera's Auto with the ability to adjust the exposure settings and have the camera maintain the same exposure. You might find Pro-mode is even more efficient than your Auto to Manual changeover.

Digital cameras (all of them) are biased toward the lowest ISO. They'll shoot at slower shutter speeds and / or wider apertures to maintain the low(er) ISO. That lowest ISO is many times to the detriment of the best image, being too slow in low light or too wide for a lens that should be stepped down for sharpness.

Cameras also have to be 'told' to expose to the right (or left) of the 0-mark in the meter. In Pro-mode, especially when shooting RAW, you can use Exposure Compensation (EC) to 'tell' the camera to expose at a default +0.7 to +1 over / to the right of the 0-mark. That EC works in Aperture and Shutter Priorities too.

So, are you learning in Manual or just fiddling with all the dials? When you consider your lenses, do you know the best apertures for each lens? Do you know the max / highest ISO to limit your camera? Do you have a internal 'feel' for the minimum speed needed to freeze motion for different situations, such as resting animals, swimming ducks, flying eagles? Are you seeking to develop an intuitive sense of your equipment, the light, and the subject such that you dial in the manual parameters, position the AF point, and raise the camera and start delivering 'keepers' from frame 1?

That paragraph and questions above define the situation where you are one with your camera. That's when the magic begins. You can be just as successful in Aperture or Shutter Priority, shooting modes I use on my film and mirrorless cameras respectively. Manual can be more work with less success unless every aspect of exposure and the equipment is intuitive. And of course, it takes lots of practice and time. Consider your true destination and the best path that leads you there.