This is the second article in the series of Brown Pelican taking advantage of the masts and rigging of shrimp boats. The first article is here and is mainly closer shots of the Pelicans.
Shrimp boats use outriggers on either side to drag their nets. They also have multiple riggings with hanging nets. To a Pelican it just means choices of where to sit.
Not being a shy bird they are fine sharing if needed.
Apparently they read upside down too.