Our house has many chimneys, installed long before the central heating was. One, lined, is attached to a wood-burning stove. Another is well-capped. The other two are not, but will be soon. One of those, hooded but uncapped, leads to what was originally a coal-burning fireplace in C.'s office, unused for years. That's where the bird was.
So first, we emptied out scads of things from the room until there was little left, draping the computer in a large dropcloth. Then, C. took off the flue-cover and a mountain of dust and dirt tumbled out. We held our breaths, but no bird. Eventually - it seemed the best approach - I went outside to watch the window to the office, to see if and when the bird flew away. (We really, really hoped it was up to flying.)
It took what felt like ages. After a while, I saw a flutter of black wings from a blackbird within, but it then went and hid among the folds of the dropcloth. C - after quite a while more - successfully scared it forth. It flew!
I went upstairs to cheer with C - when there was another squawk. There was another bird trapped in the chimney.
I think this one took even longer. It was really failing to come out. Pest removal places wouldn't deal with birds in chimneys. The internet suggested shining a flashlight up the chimney, so the bird would know which way to go.
And indeed, shortly after a flashlight was deployed, the bird came forth, flying much more promptly out the window.
We're guessing they were trying to nest in the chimney. In any event, it's the first time we've had birds stuck in our chimney. The joys of home ownership? In any event, as a result of the mess, C has as clean an office as he has had in years.
And that is how we now come to have the correct number of birds stuck in our chimney.