Field marks

The term comes from the printed field guide tradition, where an illustration would carry little arrows pointing at the two or three features that actually settle the identification. They remain the right way to check an app's suggestion, because they are things you can see in your own photograph rather than things you have to take on trust.

When a suggestion looks wrong, go to the marks. Is the bill thin or conical? Is there a wing bar, and how many? Does the eye have a ring or a stripe through it? A photograph that does not show any diagnostic mark is a photograph that cannot be identified with confidence, no matter how certain a model sounds.