Birds watching

When I walked around the park after a long while,I noticed something strange.
It was the birds staying at the canal differently as usual as before.
I had often seen a big seagull among the other seagulls. I thought it was a boss of the flock and I named him a pig gull. It was twice as big as the normal ones.

But this time I didn't find that big seagull but the heron instead of the pig gull. I'm worried about the boss if he lost his seat.
I need to admit nature is sometimes severe and cruel.
There seems to be classes between the heron, seagulls and ducks. They stay on classified places to get along each other.