Pied shag (cormorant) drying wings
This rather damp pied shag is drying his wings - shags don't have an oil gland like other water birds, so don't oil their wings
This helps with diving as they are less buoyant, but does mean that if they get too wet they could drown, so after a fishing session they must find somewhere to stand and dry their wings.
They often get into small groups, and often also go to the same roosting spot. sometimes they roost in trees near the water and over time may kill the tree.
this bird has been fishing in the Avon-Heathcote estuary which at the moment is very muddy, which explains the dull feathers.