Two years in a row, I have seen this in Juanita Bay Park. There are some trees that have some red berries on them in the fall and the crows seem to love them. They can flock to the trees in large numbers sometimes. I assume the fruity casing of the berries is appealing as they do like them. However, when I get closer, the crows seem to get nervous. A little video to add to show one of the crows having a good chomp.