Males of the species Struthio camelus can reach a whopping 2.75 tall. These flightless birds are incredible runners.

Once believed to be a subspecies of the common ostrich, Struthio molybdophanes was confirmed as a separate species in 2014.

The southern cassowary (Casuarius Casuarius) is only slightly larger than its cousin, the northern cassowary.

Like other species of cassowary, Casuarius unappendiculatus is a flightless bird. After being laid by a female.

Of the four surviving members of the family Casuariidae, three are cassowaries, and the fourth is the emu.

This iconic species can stand as tall as 115cm and weigh up to 46kg. Aptenodytes forsteri will trek up to 120km.

This grassland-dwelling species, Rhea americana, is omnivorous. As well as plants, it likes to eat grasshoppers, lizards, and frogs.

Rhea pennata is also known as Darwin's rhea after the naturalist studied the species on his second voyage on the Beagle.

Despite its name, the mute swan (Cygnus olor) is a vocal bird, though its voice is quieter than other species.