The cache is completely out in the open and can be spotted easily. This is a gadget, where the objective isn't to find it; it is to open it. The bird house style container DOES NOT need to be taken apart or pried open.
Inside the cache you'll find a puzzle, a tool you'll need to solve the puzzle, and a locked compartment containing the log book. If consonants are positive and vowels negative, all you need to open this blue bird love nest is arithmetic. You may be required to do some deep thinking, but it is not rocket science.