Ross' Goose

Ross' Goose -- Merced National Wildlife Refuge, CA
Canon EOS Rebel T5i, EF 100-400mm f/4.5-5.6L IS II USM, ISO: 320, f/5.6, 1/1600s

Why is it that when geese stand together in a flock almost all of them stand facing the same direction?

Seriously, I want to know.  I see this over and over and I don't know why this is.