Merlin is amazing. I heard birds outside my new apartment and thought of them as nice background noise. Within days of installing Merlin, I could tell sparrows, cardinals and robins apart without seeing them. Whenever I heard a new bird, I'd grab my phone and open Merlin.

One day it sounded like a robin and a cardinal were having and argument while both simultaneously having a stroke. Merlin figured out it was a catbird, a relative of the mockingbird that learns the songs of other birds then strings pieces of them together in a disorganized song to impress the ladies. Basically, the male catbird who can sing the weirdest songs using the most species signals that he has "been around" for enough seasons to learn all those songs and therefore must have good genes the females want to pass on. It's mind blowing to learn all this about things that are going on outside your window.