Blackbirds at the Lek...

I have just been watching 3 Blackbirds acting more like Black Grouse at a Lek. They each flew down & did their usual 'Bow & Run' routine, in different directions, but instead of 1 or 2 then being chased away by the 3rd, they turned & faced each other, Bowing with wings pulled away from their Breasts but aimed up. They then moved in & out a few steps forward & backwards. This continued for about 30 seconds, up they jumped flapping their wings & flew off. I have never seen this outside a Lek & with Black Grouse Cocks. A first for me