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).