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Tinamous and Ratites: Struthioniformes

Physical Characteristics

Struthioniformes are divided into two groups: ratites (RAT-ites), which are flightless birds that have a flat breastbone rather than a keeled breastbone (shaped like a wishbone) like birds of flight; and tinamous (TIN-ah-mooz), which have a keeled breastbone and can fly. Ratites have a simplified wing bone structure, strong legs, and no feather vanes, making it unnecessary to oil the feathers. Consequently, they have no preen gland that contains preening oil. This group is composed of ostriches (Struthionidae), rhea (Rheidae), cassowaries (Casuari-idae), emus (Dromaiidae), and kiwis (Apterygidae).

Ratite sizes range from 10 inches (25 centimeters) to 9 feet (2.7 meters) and weight can be from 2.86 pounds (1.3 kilograms) to 345 pounds (155.25 kilograms).

Ostriches are the largest struthioniforms (members of the Struthioniformes order), with long legs and neck. They range in height from 5.7 to 9 feet (1.8 to 2.7 meters) and weigh from 139 to 345 pounds (63 to 157 kilograms). They have loose-feathered wings. Males have black and white feathers while the female has grayish brown feathers.

Emus are about 6.5 feet in height and weigh 51 to 120 pounds (23 to 55 kilograms). They have long, strong legs and can run up to 30 miles per hour (48 kilometers per hour). They have short wings and the adults have brown feathers.

Rheas are 4.5 to 5.6 feet (1.3 to 1.7 meters) and weigh 55 to 88 pounds (24.75 to 40 kilograms). Their feathers are gray or spotted brown and white.

Cassowaries are 3.3 to 5.6 feet (1 to 1.7 meters) in height and weigh 30 to 130 pounds (14 to 59 kilograms). They have tiny wings with black feathers.

Kiwis are the smallest of ratites, ranging in height from 14 to 22 inches (35 to 55 centimeters) and weight 2.6 to 8.6 pounds (1.2 to 3.9 kilograms). They have brown and black hair-like feathers.

The tinamous have a keeled breastbone (shaped like a wishbone) and can fly. They range in size from 8 to 21 inches (20 to 53 centimeters) and weigh 1.4 ounces to 5 pounds (43 grams to 2.3 kilograms).

Additional topics

Animal Life ResourceBirdsTinamous and Ratites: Struthioniformes - Physical Characteristics, Behavior And Reproduction - GEOGRAPHIC RANGE, HABITAT, DIET, RATITES TINAMOUS AND PEOPLE, CONSERVATION STATUS