Birds are a diverse group of vertebrates that are characterized by their feathers, toothless beaked jaws, laying hard-shelled eggs, and high metabolic rate. While all living birds have wings, not all species are capable of flight. There are over 10,000 species of birds alive today, occupying ecosystems across the globe from the Arctic to the Antarctic. When it comes to legged birds, ostriches and emus stand out as unique.
What makes ostriches and emus special?
Ostriches and emus are large, flightless birds that belong to a group called ratites. Ratites are distinguished by their flat breastbones and inability to fly. Other ratites include rheas, cassowaries, and kiwis. Ostriches are native to Africa, while emus hail from Australia. These big birds share some key traits:
- Powerful legs for running – Ostriches and emus have long, muscular legs suited for running. Ostriches can sprint up to 43 mph, making them the fastest land bird. Emus clock in at 31 mph.
- Long necks and legs – They have elongate necks and legs compared to their bodies. This gives them a height advantage to spot predators and reach high vegetation.
- Sharp eyesight and hearing – Their large eyes and ears also help detect threats in their open environments.
- Shaggy plumage – Both species have shaggy, two-toned feathers. Ostriches have black and white plumes, while emus have brown and cream feathers.
- No keel on breastbone – Their flat breastbones are unlike other birds, allowing for large muscle attachments to power their strong legs.
- Powerful kicks – Using their clawed feet, they can deliver dangerous kicks to predators. Ostriches use kicks as their main defense.
These adaptations allow ostriches and emus to thrive as highly successful cursors. A cursor is an animal specialized for running. Despite their hefty sizes, ostriches and emus are nimble runners able to cover great distances. Their speed and kicks help them avoid predators in the open landscapes they inhabit.
Ostrich Facts
Here are some key facts about ostriches:
- Height: 6-9 feet
- Weight: 220-350 pounds
- Lifespan: 30-40 years
- Habitat: Savannas and deserts of Africa
- Diet: Plants, seeds, insects, small mammals, reptiles
- Unique traits:
- Largest living bird species
- Can go weeks without drinking water
- Males incubate and raise young
- Have just two toes on each foot
Some key behaviors of ostriches include:
- Living in nomadic flocks of 5-50 birds
- Sprinting away from threats; using kicks as last defense
- Males establish breeding territories; mate with several females
- Females lay 6-15 eggs in communal nest; males incubate eggs
- Adults raise young together for 6 months until independent
Ostriches are farmed around the world for their meat, feathers, eggs, and leather. Their speed and kicking power make them difficult to confine. Ostriches also have inspired many myths and legends throughout Africa.
Emu Facts
Here are some key facts about emus:
- Height: 5-6 feet
- Weight: 90-120 pounds
- Lifespan: 10-20 years
- Habitat: Woodlands and grasslands of Australia
- Diet: Plants, seeds, flowers, insects, small vertebrates
- Unique traits:
- Second largest living bird after ostrich
- Make loud booming and grunting sounds
- Males incubate eggs and raise young
- Have three toes on each foot
Some key behaviors of emus include:
- Living in flocks of up to 50 birds
- Traveling great distances for food and water
- Males build nests and incubate eggs for 50-60 days
- Chicks stay with father for 18 months until independent
- Can go months without drinking water
Emus are farmed for their meat, oil, and leather. They are also cultural icons of Australia, even appearing on the country’s coat of arms. Wild emus face threats from hunting and habitat loss.
Ostrich vs Emu: How Do They Compare?
Ostriches and emus have similarities reflecting their membership in ancient bird groups. But they have some notable differences stemming from their evolution in separate environments.
Trait | Ostrich | Emu |
---|---|---|
Height | 6-9 feet | 5-6 feet |
Weight | 220-350 pounds | 90-120 pounds |
Range | Africa | Australia |
Habitat | Savannas, deserts | Woodlands, grasslands |
Diet | Omnivorous | Herbivorous |
Top speed | 43 mph | 31 mph |
Toes per foot | 2 | 3 |
In summary, ostriches are taller, heavier, faster and found in Africa, while emus are smaller, herbivorous, slower and native to Australia. But they share key ratite features like flightlessness, running prowess, and parenting by males.
Flightless Bird Evolution
Ostriches, emus and other ratites lost the ability to fly due to separate evolutionary paths. Here is an overview of their evolution:
- Ratite ancestors were flying birds related to waterfowl and gamebirds.
- As continents drifted apart, ratite forebears were isolated from each other.
- With fewer ground predators, they adapted for cursorial lifestyle over flight.
- They lost flight muscles and breastbone keel; gained running traits.
- Today ratites are found across former supercontinent Gondwana.
- Ostriches evolved in Africa, rheas in South America, emus and cassowaries in Australasia.
- Some think early human activity caused ostrich, emu extinctions elsewhere.
While genetic analyses show ratites like ostriches and emus descended from a flying ancestor, their wings and flight ability were lost over millions of years as they specialized for running.
Threats Facing Ostriches and Emus
As predominantly ground-dwelling birds unable to fly from danger, ostriches and emus face a range of threats to their survival:
- Habitat loss – Conversion of wild grasslands and savannas for agriculture reduces habitat for ostrich and emu populations.
- Hunting – Ostriches and emus are hunted, sometimes illegally, for meat, skins and feathers. Their eggs may also be taken.
- Vehicle collisions – Their ground habitats make ostriches and emus vulnerable to being struck by vehicles.
- Predation – Large African predators like lions, cheetahs, hyenas, leopards prey on ostriches. Dingoes hunt emus.
- Climate change – Shifting temperatures and precipitation patterns may alter habitat ecology critical for ostriches and emus.
Further research and conservation measures are needed to protect ostriches, emus and other flightless ratites into the future.
Conclusion
Ostriches and emus are remarkable legged birds adapted for running and life on the ground. As the largest living ratites, they share traits like flightlessness, speed, and male parenting but have evolved differences suited to Africa and Australia. Though ecological changes pose challenges, learning more about these unique birds can help conserve them for generations to come.