How to meter white birds/BIF

[ac12]

I shoot full manual, but as you mention... I choose Auto ISO. Is that my downfall?

Yes.
Auto ISO means the camera is adjusting the exposure by adjusting the ISO level.
Therefore, you are NOT in full manual.
To be in full manual, you need to be in control of the 3 sides of the exposure triangle; shutter speed, aperture, ISO level.
You need to turn the mode to M (manual) and turn auto ISO OFF, to be in full manual.

Absolute GARBAGE reply unless you can explain WHY it would benefit him.

Since YOU think it is garbage, why don't YOU explain it.

 

[zombiesniper]

I do think it was a garbage post. It in no way aided the OP in solving their problem.

Why would I explain it? You posted some crap to try and make yourself look superior and got called on it. You're acting like a child.

 

[Derrel]

I shoot full manual, but as you mention... I choose Auto ISO. Is that my downfall?

Yes.
Auto ISO means the camera is adjusting the exposure by adjusting the ISO level.
Therefore, you are NOT in full manual.
To be in full manual, you need to be in control of the 3 sides of the exposure triangle; shutter speed, aperture, ISO level.
You need to turn the mode to M (manual) and turn auto ISO OFF, to be in full manual.

Full manual versus manual with AUTO ISO enabled...two subtly different things.

In the daisy in front of brown background example that zulu42 showed, note that we have a small white-petaled flower, surrounded by about 89 percent of the frame being a dark brown color. The tone curve is important here--the situation has VERY high contrast...white flower, dark background. The most critical thing is not to blow out the highlights, and then to apply the right degree of contrast to make the shadows look good, so we have a need for post processing and careful exposure setting in-camera.

There is the field stage and the computer stage. In you OP, you show a small-in-frame white bird seen against a pretty dark background...I would guess that as much as 1.7 EV of exposure compensation might be needed with this scene, and maybe some computer "tone work" to make the scene read right.