There are 35 species of seals in the world. Duiker Island is a Cape Fur Seal and bird sanctuary, home to thousands of seals and many birds such as the Cape Cormorant, the Bank Cormorants, Black Back Gulls, Kelp Gulls and Hartlaub Gulls. It is illegal to go onto the island. The majority of the seals on Duiker Island are males waiting out their time until they reach the right breeding age, which is between the ages of 8 to 12 years depending on their size. Duiker Island is not a breeding colony as the sea can get very rough and the pups get swept off.