This is serious!
Partial defination of “secret”, from m-w:
Is that fly speck on my closet ceiling a secret?
Also, is a pebble at the bottom of the Mariana Trench hidden?
In case the question arises unbidden, the answer to the bear poop query is yes, as is the tree noise one.
And the chicken came first because the bible says so.
Peace,
mangeorge
Key word is “kept”. There must be intent involved in the hiding or making mysterious of whatever is the secret. It’s not secret if it’s merely unknown or undiscovered (although the word is sometimes used in this sense).