Australasian Gannet
Morus serrator
An adult Australasian gannet is 84–91 cm (33–36 in) long, weighs 2.3 kg (5.1 lb), and has a 170–200 cm (67–79 in) wingspan. The two sexes are generally of a similar size and appearance, though a 2015 field study at Pope's Eye and Point Danger colonies found females to be 3.1% and 7.3% heavier respectively. Females also had a slightly larger ulna and smaller bill. The plumage is white with black flight feathers on the wings, and central rectrices of the tail. Some individuals have more extensive black plumage of their tail feathers. There is a sharp demarcation between light and dark plumage. Voice: The Australasian gannet is generally silent at sea and loud and vocal at the colony in the day and at times overnight during the breeding season. Its typical call is a harsh arrah-arrah or urrah-urrah, which is emitted upon approaching or arriving at the colony or as a threat. The calls can vary between individuals, and the female's call is lower pitched than the male's.
ID text from Wikipedia, CC BY-SA 4.0
Cape Gannet
Morus capensis
When seen in flight the snow-white body with the black tail, primaries and secondaries, and dark bill makes them easy to identify. At closer range the distinctive golden crown and nape, which gradually becomes white on the neck, is noticeable. Juveniles and immatures are dark brown with a pale bill, and can resemble the dark-coloured boobies at first glance. Adults are about 84–94 cm (33–37 in) long and have a 171–185 cm (67–73 in) wingspan and weigh ca. 2.6 kg (5.7 lb).
ID text from Wikipedia, CC BY-SA 4.0
Where you might meet both
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