dawn chorus 
noun British
The singing of a large number of birds before dawn each day, particularly during the breeding season: the dawn chorus woke Robyn at five...
- Such findings support the idea that singing during the dawn chorus is important to defend the territory against rival males or to adjust social relationships among territorial neighbors.
- The morning burst of birdsong is called the dawn chorus.
- A poet who didn't wake for a dawn chorus like the ones you get here would be a sad fellow indeed.