In some places blackbirds are a sign that cold weather is coming. They come down from the higher altitudes/mountains and avoid freezing/starving. Blackbirds are pretty smart too. As a kid I tried to shoot them however they seemed to 'know' when I was about to fire. I could hit anything with my pops lithgow .22, anything except for crows and currawong that is.
Love Bob

Thanks Bob,, I'm a hunter also... Some critters are smart... lol