Now hear this! Now hear this!

"Did you hear that?"
"What?"
"A Goldcrest calling."
"No."
"There's an influx of Yellow-browed Warblers. Well worth listening out for."
"Sure, if you can hear their high-pitched calls."
"Listen! Isn't that a Treecreeper calling?"
"Isn't WHAT a Treecreeper calling?"
We call our sport (or used to call it) "birdwatching", but any aficionado will tell you that 7 times out of 10, or so, you identify birds on CALL or SONG well before you see them, if you in fact ever see them. It ought to be called "birdlistening".
So, when you start to lose the higher frequencies, it's in a way worse than losing your visual acuity. I am slowly saying farewell to the sopranos, but still have a sporting chance with the altos.
"Bullfinch!"
Ah, good karma. I can say:
"Yes, I heard it too."
And I can still hear Long-tailed Tits and Willow Warblers and Chiffchaffs and........
Seems there's a dance or two in the old dame yet, as Mehitabel was wont to say.
Envoi:
The diagram at the top of this post is a sonagram, a faithful graphical representation of the sounds made by............well, can you identify the species?! I sure as hell can't.