Once you have fed several hundred baby birds for several years, as I have, you get to know the calls of most of the common birds in this area. When I go for a walk, I can hear the babies calling to the parents for food.
This year, we've had several species of birds nesting on our property. A couple of weeks ago, the cardinals fledged. This morning, while I was in the kitchen fixing breakfast, I heard the unmistakable "fingernails-on-a-chalkboard" call of two baby mockingbirds. The parents may have a beautiful song, but the babies just have a one-note, high-pitched call that just grates on my nerves. Sure enough, I looked out the window over the sink and two fledged mockers were nagging mom and dad for breakfast. As this point they are out of the nest and can flutter short distances. They were following their parents, just so they wouldn't forget they were hungry. Like they could forget!
Soon the babies will be self-sufficient and on their own, and my ears will get a rest.