This video from the USA says about itself:
18 February 2018
Stunning male Red-Winged Blackbirds in classic singing and displaying mode for Spring! I could watch these guys all day. I have several videos of RWBB‘s, but this is my best sound recording so far. No man-made noise and using an external shotgun microphone for DSLR.
After some 20 years of theorizing, a scientist is publicly renouncing the “beautiful hypothesis” that male birds’ sexy songs could indicate the quality of their brains: here.