Like their close relatives the gannets, boobies belong to the Pelecaniformes order and are strictly marine birds, only coming ashore to breed and nest. But unlike gannets, they are birds of the tropics and subtropics. Only one species, the masked booby (Sula dactylatra), breeds in New Zealand, but brown boobies (Sula leucogaster) regularly occur as vagrants, as far south as Nelson.
Around 200 pairs of masked boobies breed on the Kermadec Islands, New Zealand’s northernmost offshore group, 700 kilometres north-east of North Cape. Masked boobies are also found breeding on islands belonging to Australia – Lord Howe, Norfolk, Nepean and Phillip islands.
Once numerous, masked boobies were nearly hunted to extinction on Lord Howe Island and Norfolk Island. Today, longline fishing poses a threat to birds at sea.
It is believed that the word booby comes from the Spanish ‘bobo’, meaning a dolt, or stupid person. The term was used for large seabirds that were easy to kill.
At a distance, masked boobies resemble white-headed gannets. Named for their mask-like facial skin, which is blue-grey, they are the largest of the boobies – nearly 1 metre long and with a wing span of 1.5 metres. The sexes are similar in size and appearance, although males typically have a brighter yellow bill than females. Adults have white bodies and dark brown-black flight and tail feathers. Juveniles have greyish-brown upper bodies and a grey bill.