dawn chorus

noun2

1. •
   Birdsong by a large number of birds occurring in the early morning.

   • Staying just under a mile from Gillingham station, I was up before the dawn chorus and parked at the station car park (£5.20 all day) in time for that 0456. — 2020
2. •
   Radio interference sometimes experienced at sunrise.

   • The frequency spectrum (Fig. 1) includes micropulsations (Pₜ, P_c, LP_c, PP, SIP, IPDP), gyromagnetic resonances, Schumann resonance, solar whistlers[…], dawn chorus, hiss, whistlers and sferics. — 1964