― Douglas Adams, Life, the Universe and Everything
I suspect most bird chatter is about sex, not flying.
Like when you're out in the summer evening, and the crickets are chirping and the frogs are croaking, and you realise it's just a whole bunch of males shouting "hey baby, over here!"
All the chirping I had ever heard basically means the same thing as most of what my peers were saying in junior high.
As much as I like Douglas Aadms, this statement is just wrong. A lot of bird chatter is songs to demarcate territory, threat warnings, contact calls to maintain flock awareness, young birds saying 'feed me', and others.
I know when a cat has entered my garden by the clucking warning calls that the blackbirds make. They make a different warning noise when I interrupt them on my bird feeder. Sometimes I'm alerted to a buzzard by the calls of rooks who are ganging up on it.
I'll float around your head for hours just to prove you wrong!
The other case is juvenile magpies. As adults I mostly hear them shouting aggressively at each other. But if the youngsters don't know I'm there, I've sometimes heard them chatting. The sounds they make are complex and quiet. A bit like this https://www.youtube.com/watch?v=8P4ZVgjslVQ but I've always seen them in pairs or groups when doing this.
Third is the Robin (European). They also have a whisper song. Sometimes they do it so quietly that I have to be within a few feet to hear it. And there's no other bird around. I guess it's a male who is just working on new material to impress the ladies with later.
> “The booming [mating call] is deep, very deep, just on the threshold of what you can actually hear and what you can feel. This means that it carries for very great distances, but that you can’t tell where it’s coming from. If you’re familiar with certain types of stereo setups, you’ll know that you can get an additional speaker called a sub-woofer which carries only the bass frequencies and which you can, in theory, stick anywhere in the room, even behind the sofa. The principle is the same: you can’t tell where the bass sound is coming from.
> The female kakapo can’t tell where the booming is coming from either, which is something of a shortcoming in a mating call. “Come and get me!” “Where are you?” “Come and get me!” “Where the hell are you?” “Come and get me!” “Look, do you want me to come or not?” “Come and get me!” “Oh, for heaven’s sake.” “Come and get me!” “Go and stuff yourself” is roughly how it would go in human terms.”
Excerpt From: Douglas Adams & Mark Carwardine. “Last Chance to See.” Apple Books. https://books.apple.com/us/book/last-chance-to-see/id4608191...
(I once emailed Adams asking when this book would be published in paperback, this was back when the Internet was small enough that one could sleuth and guess nearly anything. He responded three years later, saying that Random House had published it with "the worst cover I've seen in my career.")