Fish vs Birds. Sounds crazy but maybe when various lifeforms emerged from the sea to take to the skies eons ago they could have kept some behavioral traits. They seem to have the same behavior at times. For instance schooling fish appear similar to types of migratory birds, especially where I live in the east, where huge numbers of birds fly close together and change directions suddenly and fluidly in the sky. I've heard that it has something to do with the way they're brain works that causes this.