What is that white stuff on Robberg?

While on our boat trips many people ask me what the white stuff is on Robberg. It kind of looks like someone took white wash to the rocks.
Well there is a very simple answer. It is bird guano. There are many Cape Cormorants that roost on Robberg and they are roosting in a staggered formation and often one above the other. When they leave their dropping, it runs down the side of the mountain leaving the very white look along patches of the mountain.
These birds often nest and feed in flocks and are found in the bay year round. They are very good diving birds often seen by divers eating the fish on the reefs. Because their feathers lack the oils that other birds have to maintain good health for their feather and to repel water, they are often seen waving their wings gently in the wind to dry them.