This is an online definition of the dawn chorus.
The dawn chorus occurs when birds sing at the start of a new day. In temperate countries this is most noticeable in spring when the birds are either defending a breeding territory, trying to attract a mate, or calling in the flock. In a given location, it is common for different species to do their dawn singing at different times
The reality for me in Beetley is that for the last ten days or so, the birds in the garden have started this while it is still dark. The noise increases in intensity as different birds join in, then comes the cooing of the pigeons, and the squawking of the crows to cap it off.
It goes on for at least an hour until they calm down, by which time I am wide awake, far too early for my liking. On a good day, I might be able to get back to sleep for a couple of hours, but most days I am left awake, knowing it is too early to get up.
No point complaining. It is a delightful thing to have, especially as it is the only sound, and not accompanied by sirens, traffic, trains, or helicopters.
I just wish those birds would have a lie-in occasionally.