They are easily identified by their large size, black and white plumage and distinctive yellow crown and hindneck.

Early Sulidae fossils most resembled the boobies, although they were more aquatic, with the gannets splitting off later, about 16 million years ago.

The most ancient extant species may be the Abbott's booby, possibly the sole survivor of an otherwise extinct separate lineage.

[3] A 2011 genetic study of nuclear and mitochondrial DNA suggests that the ancestor of the gannets arose around 2.5 million years ago before splitting into northern and southern lineages.

[5]When seen in flight the snow-white body with the black tail, primaries and secondaries, and dark bill makes them easy to identify.

Cape gannets are powerful fliers, using mainly a flap-gliding technique, which is more energy consuming than the dynamic-soaring favoured by albatrosses.

Several birds have occasionally been found breeding on offshore Australian islands, together with Australasian gannets, although the Cape species is never represented by more than a few pairs.

Numbers of Cape gannets at the Namibian islands have declined considerably between 1956 and 2000 from 114,600 to 18,200 breeding pairs respectively, an 84% decrease in less than fifty years.

This contrasts with the trends at the South African islands where numbers have increased about 4.3 times during the same period, from 34,400 to 148,000 breeding pairs.

A retransposition of the original latitude and longitude gives a location off the Namibian coast, well within the regular wintering range of the species.