Ratites
What is a ratite?
Ratities are a group of birds which are grouped together based on their smooth sternum or breastbone. This is due to it lacking a keel where the flight muscles can be anchored. This means that all birds in this group are flightless.
Four groups of these birds are alive today with 12 species included in them. These include the kiwis of New Zealand, the cassowaries of Australia and New Guinea, the emu of Australia, the Ostrich from Africa and the rheas of South America.
A number of extinct species are also included in this family such as the moa of New Zealand and the elephant bird of Madagascar.
The largest extant (currently living) member of the ratite family is the ostrich with males reaching heights of up to 2.8m (9.25ft). The smallest member is the kiwi which averages 50-65cm (20-26in).
In recent times members of this group such as the emu, rhea and ostrich have increased in popularity for farming.
Ratites are found on the continents which previously made up Gondwana, the former supercontinent which included South America, Australia, Madagascar, Africa and New Zealand.
The name ratite comes from the Latin word 'ratis' meaning raft and referring to a boat without a keel.
Originally it was thought that these birds shared a common flightless ancestor and spread across the world but more recent research has suggested these animals are the result of convergent evolution and developed their flightlessness independent of one another.
In four of the families (rheas, cassowaries, emu and ostrich) the male is the primary carer for the young.
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Types of Ratite
Ratities are birds which are flightless. Meet the 5 main types of bird in this group below and learn more about the individual species by visiting our fact file pages using the buttons.
Ostrich
Ostriches are the largest member of the ratite group and the largest bird currently alive generally. The may stand up to 2.8m (9.25ft) tall.
Males have darker black feathers compared to the brown feathers of the female.
They are unique as the only bird which has two toes on each of its feet.
Learn more about the ostriches appearance, diet, habitat, breeding and behavior with our fact file by clicking the button below.
Emu
Emus are the second largest member of the ratite group and the largest bird to live in Australia.
They live across the Australian mainland and were previously found in Tasmania but are now extinct there.
Learn more about the emus appearance, diet, habitat, breeding and behavior with our fact file by clicking the button below.
Cassowaries
The cassowaries are a group of three extant species. The southern cassowary is found in Australia and New Guinea while the dwarf cassowary and northern cassowary can be found New Guinea and other nearby islands.
A fourth species the pygmy cassowary is known from fossils but is now extinct.
They share a feature in the hard casque which sits on top of their head. The purpose of this growth is still being debated among scientists. Females tend to be larger than males in this species.
Learn more about the southern cassowaries appearance, diet, habitat, breeding and behavior with our fact file by clicking the button below.
Rheas
Rheas are a group of two species which live in South America. Their is the greater rhea and the lesser or Darwin's rhea.
They appear similar to a female ostrich but are much smaller and have three toes as opposed to two for the ostrich.
Rheas tend to live in groups. Males will tend the eggs of up to twelve females which they have mated with.
Learn more about the greater rheas appearance, diet, habitat, breeding and behavior with our fact file by clicking the button below.
Kiwis
The kiwis are a group of 5 species which includes the North Island brown kiwi, southern kiwi, Okarito kiwi, great spotted kiwi and little spotted kiwi. The largest is the great spotted kiwi while the little spotted kiwi is the smallest.
These birds are the smallest of the ratites and feature a long bill which is used to obtain their diet of insects from the ground. They are covered by hair-like feathers and are primarily active at night.
Their eggs are very large in relation to the size of their body.
Learn more about the North Island Brown Kiwis appearance, diet, habitat, breeding and behavior with our fact file by clicking the button below.
References
Sciencedirect.com. 2020. Ratites - An Overview | Sciencedirect Topics. [online] Available at: <https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/ratites> [Accessed 29 December 2020].
Veterinary Manual. 2020. Overview Of Ratites - Exotic And Laboratory Animals - Veterinary Manual. [online] Available at: <https://www.msdvetmanual.com/exotic-and-laboratory-animals/ratites/overview-of-ratites> [Accessed 29 December 2020].
Sciencewise.anu.edu.au. 2020. The Mystery Of The Ratites - Sciencewise - ANU. [online] Available at: <http://sciencewise.anu.edu.au/articles/Ratites> [Accessed 29 December 2020].
Burnie, D., 2011. Animal. 3rd ed. London: DK
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