What South American bird is similar to an ostrich?

There are several large, flightless birds native to South America that bear some resemblance to the ostrich, which is found in Africa. The two main candidates are the rhea and the Darwin’s rhea. Like ostriches, these birds have long legs and necks, small wings unfit for flight, and feathers that lack the complex structure seen in most flying birds. They inhabit open grasslands and scrublands, where they can run swiftly to escape predators. Their diets consist mainly of plant material like leaves, seeds, and fruits. In this article, we’ll take a closer look at the characteristics and habits of the rhea and Darwin’s rhea to understand how they compare to their distant relative, the ostrich.

Rhea

The rhea is a large, flightless bird that lives in open grassland habitats in South America. There are two different species of rhea:

• Greater Rhea (Rhea americana) – Lives in east-central South America
• Lesser Rhea (Rhea pennata) – Lives in southeastern South America

Some key facts about the rhea:

• Can grow up to 5 feet (1.5 m) tall
• Weighs 55-100 lbs (25-45 kg)
• Long legs with scaled, featherless lower legs and feet adapted for running
• Long neck with small head
• Small wings unfit for flight
• Grey-brown plumage with fluffy “bustle” feathers on back
• Omnivorous; diet includes leaves, seeds, fruits, insects, and small vertebrates
• Lays eggs in a nest in a shallow depression on the ground
• Males incubate and raise the young

In many respects, the rhea is quite similar to the ostrich found in Africa. Like the ostrich, the rhea is a large, fast-running bird with long legs, a long neck, small non-functional wings, and a diet suited for living in open grassland habitats. The rhea differs in having feathers over its whole body including the legs and lower thighs. It also has a more omnivorous diet compared to the primarily plant-eating ostrich. Overall, the rhea fills an ecological niche in South America similar to the ostrich’s niche in Africa.

Greater Rhea

The greater rhea is the larger of the two rhea species. It stands about 4.2-5 feet (1.3-1.5 m) tall and weighs 55-100 lbs (25-45 kg). Greater rheas inhabit open grasslands, scrublands, savannas, and pampas up to 5,250 feet (1600 m) elevation. They are found in east-central South America in southeast Bolivia, Paraguay, southern Brazil, Uruguay, and northeastern Argentina.

Lesser Rhea

The lesser rhea is slightly smaller at 3.3-4.2 feet (1-1.3 m) tall and weighing only 22-44 lbs (10-20 kg). It has lighter gray-brown plumage compared to the greater rhea. Lesser rheas are found further south in open habitats in southeastern South America. Their range extends across eastern Argentina into southern Brazil, Uruguay, and Paraguay.

Darwin’s Rhea

Darwin’s rhea (Rhea pennata pennata), also known as Darwin’s lesser rhea, is a subspecies of the lesser rhea native to South America. Here are some key facts about this large flightless bird:

• Endemic to central and southern Argentina and southern Chile
• Inhabits shrublands, grasslands, savanna, and scrub forest
• Grows up to 1.1 m (3.6 ft) tall, weighs 15-27 kg (33-60 lbs)
• Mainly grey-brown plumage with white tips on wing feathers
• Long legs, long neck, small head, reduced wings
• Primarily herbivorous; eats leaves, seeds, fruits, shoots, flowers
• Lays eggs in ground nest; males incubate and raise chicks
• Classified as Near Threatened; population decreasing

Darwin’s rhea is smaller and lighter in weight compared to other rheas. It is distinguishable by the white tips on its wing feathers. Darwin’s rhea was named by Charles Darwin who noticed differences from southern lesser rheas while on his voyage aboard the HMS Beagle. Habitat loss and hunting have caused the Darwin’s rhea population to decline.

Comparison to Ostrich

In many ways, Darwin’s rhea resembles the ostrich:

• Large flightless bird adapted for running
• Long bare legs with scaled skin
• Long neck with small head
• Reduced, non-functional wings
• Herbivorous diet
• Ground nesting and rearing of young

Key differences from the ostrich include:

• Darwin’s rhea has feathers on thighs and legs
• More adapted to scrubland compared to open plains
• Smaller size and weight than ostrich
• Eats a wider variety of plant foods like shoots and flowers

So while not exactly the same, Darwin’s rhea fills an ecological role similar to the ostrich, making it the most ostrich-like bird in South America.

Habits and Behavior

Diet

The rhea and Darwin’s rhea are omnivorous, feeding on a variety of plant and animal material. Their diets include:

• Leaves
• Seeds and grains
• Fruits
• Flowers
• Shoots and stems
• Insects
• Small lizards
• Rodents

They use their long necks to reach leaves and fruits in trees and bushes. Rheas swallow pebbles and grit to help grind up food in their gizzards. During droughts, they can go extended periods without water.

Movement

Rheas and Darwin’s rheas are fast runners, reaching speeds up to 40 mph. Their long legs with scaled skin and three-toed feet are specialized for running. They use a fast, efficient running style where both legs strike the ground simultaneously. Their wings are small and not functional for flight. Rheas can swim rivers up to 150 feet (50 m) wide.

Social Behavior

• Outside breeding season, rheas and Darwin’s rheas live in flocks of 5 to 30 individuals.
• Flocks often combine into larger groups up to 100 birds while feeding and moving.
• The flock is led by a dominant breeding male.
• Younger males stay separate or form “bachelor” flocks.
• Rheas dust bathe frequently, fluffing dirt through their feathers to clean them.

Reproduction

• Females breed at age 2-3 years, males at age 3-5 years.
• Breeding starts in spring (September to December in Southern Hemisphere).
• Males perform elaborate mating displays, jumping and spinning to impress females.
• Females lay clutches of 10-60 eggs in a ground nest or shallow depression.
• In rheas, male incubates eggs and raises chicks alone.
• Chicks can run within a day of hatching.

Rheas exhibit polyandry – females mate with multiple males and leave eggs for the males to incubate and raise. This behavior is unique among birds.

Population and Conservation

Both rhea species remain widespread and face low risk of extinction:

Darwin’s rhea has a much smaller population estimated at 1,000-10,000 mature individuals. Habitat loss and hunting have caused it to be classified as Near Threatened. Conservation measures like habitat preservation and reductions in hunting are needed to protect the Darwin’s rhea.

Conclusion

The rhea and Darwin’s rhea are the South American equivalents of the ostrich in Africa. These large, flightless birds fill a similar ecological role with their fast running abilities and adaptation to open habitats. While they share many similarities with ostriches in terms of anatomy, movement, and behavior, rheas also exhibit some unique characteristics like feathered legs and polyandrous breeding. The rhea remains widespread while Darwin’s rhea requires more conservation attention due to declining numbers. Both birds provide a fascinating example of convergent evolution between distant regions of the world.