One of the chicks is flapping its wings vigorously. This is the first time we have caught this happening this year.
Another month has come and gone. Before long, Fay's chicks will have fledged and our story will be finished for another year.
A few minutes later Fay comes in with food and all thoughts of exercise are forgotten.
Here's something odd. A bluetit arrives on the nest box hole.
It lands and has a good look inside.
The chicks think it's another feed.
But it's not. It's clearly an adult (from its white face) but also pretty clearly not Fay.
It doesn't have a marked face either so it does not appear to be Bill back for another look.
Another of life's little mysteries!