It's nuts

Actually they're not nuts, because peanuts are a legume, rather like peas and beans. 
I had some peanuts in shells, so put them out for the birds just as my Mum used to when I was a child - they didn't want to know. We have feeders that hold seeds, so the birds are well used to coming into the garden. I then shelled half of the peanuts and put them into one bag, and left the remaining half in another bag. The birds still haven't touched the ones in the shells, but they are now eating the ones that I shelled.
That's rather like MacDonald's for birds - the ultimate fast food. Obviously their tastes have changed over the years, or they have become lazier.