Is ‘proclaim’ in the sense of ‘indicate (something)’ informal?

Question

Example

The blue and yellow plumage proclaims the Cyanistes caeruleus species.

OED defines the term ‘proclaim’ as

a. trans. fig. Of a thing: to make known or manifest; to be evidence or an indication of, demonstrate; to reveal as; to show or prove to be.

The ‘fig.’ abbreviation denotes figurative, so the usage is supposedly informal. The word is also listed as an updated entry. However, every other dictionary does not list the above definition as informal, so is it formal? The audience would be professors (not specific to a subject).

Answer 1

That guilty creatures sitting at a play
Have by the very cunning of the scene
Been struck so to the soul that presently
They have proclaim'd their malefactions;
— Hamlet (act II, scene ii)

The usage is not so much informal as poetic. It may strike a serious audience as oddly high-flown, perhaps to the point of sarcasm.

Costly thy habit as thy purse can buy,
But not expressed in fancy—rich, not gaudy,
For the apparel oft proclaims the man
— Hamlet (act I, scene iii)

Answer 2

I like your sentence. Proclaim gives this bird majesty. If your audience were MacDonalds servers I'd suggest an alternative. The professors will be fine and will just enjoy it.