Peanuts in the shell. (1 Viewer)

I keep a feeder with peanuts in the shell. Bluejays, grackles and titmouse all like them. One day as I was watching them I thought how do the birds know there is a peanut in the shell. A lady on another forum guessed they go by smell or learned behavior by watching other birds. That leads me to the question, how does the first bird know?

Presumably desperation + evolution. When food is short, any species that has innate curiosity to find peanuts in a shell (or bugs under the tree bark, or worms under the ground, etc.) will be more likely to survive, and the skill is more likely to get passed on.

Nuts are basically nuts, so if they are eating one kind they would probably switch to another in a stride. What I wonder is how a Great Tit can tell a frozen slab of white bacon from the similarly shaped kitchen-sink sponge (or something else inedible) and recognize bacon is edible - in theory it could be some artificial inorganic object, especially if left on someone's balcony where there is always lots of junk.