A guide to the world’s biggest flightless birds

Greater rheas have a similar form to ostriches and emus, with large bodies, long legs and wings that won’t take them anywhere. A rhea recently escaped in England and has been on the loose since.

John Roberts/Flickr (CC BY-NC-SA 2.0)

Residents of Hertfordshire in England may have gotten a glimpse of an unusual site in the last few weeks — a large, flightless bird called a greater rhea that looks somewhat like an ostrich. The female, named Rita (and nicknamed Chris by locals after English singer-songwriter Chris Rea), escaped from captivity last month and has been on the loose ever since. She’s been spotted wandering canola fields and as of last weekend had apparently taken up residence on a golf course. Locals are threatening to shoot the three-year-old big bird, but her owner hopes to lure her back home with her favorite dog food. Her owner thinks Rita may just be looking for a mate.

Locals have been warned not to approach Rita, as rheas have dangerous claws. Actually, many of the rhea’s relatives — called ratites — can be dangerous. They can also be tasty — rheas like Rita for instance, are raised on farms for their meat. What follows is a guide to which of these long-legged, long-necked birds you should be wary of, and which ones you can eat. (Not included on the list are New Zealand’s five species of kiwis, which are all small, threatened with extinction and should be left alone.)

Ostrich (Struthio camelus)
Ostrich Artbandito/Flickr (CC BY-NC-ND 2.0)

Native to: Africa
Height: males 2.1-2.8 meters, females 1.7 to 2 meters
Weight: up to 145 kilograms
Life span: 40-45 years
Eats: Mostly plants, including seeds, fruits and flowers, but also insects.
Can I eat it? Yes. Ostriches are raised for their eggs and meat, which tastes similar to beef. The market for their feathers collapsed in the early 20th century, but the leather made from their skin is still used.
You should know: If you’re going to bake with ostrich eggs, one egg is equivalent to about two dozen chicken eggs.
What should I do if I encounter one? Be careful. Ostriches usually stay away from humans, but they can attack if they feel threatened or their young are in danger. These birds can only kick their legs forward, but their feet have long claws capable of disemboweling a person. Ostriches have been known to kill people.

Emu (Dromaius novaehollandiae)

Native to: Australia
Height: 1.5-1.9 meters
Weight: 18-60 kilograms
Life span: 10-20 years, longer in captivity
Eats: plants, insects, stones (to help digestion)
Can I eat it? Yes. Emus are raised for meat in Australia and other parts of the world, including the United States and China. Their skin is turned into leather and their fat is rendered into oil for cosmetics and dietary supplements.
You should know: An emu has a pouch in its throat that can be inflated to make deep booming sounds. Their “bloodcurdling” hisses scare off dingoes.
What should I do if I encounter one? Be cautious, as you would with any wild animal. Emus have claws but are more likely to run away from you than attack. And at the Australian Reptile Park north of Sydney, you can even pet the emus, which run loose with several kangaroos.

Southern Cassowary (Casuarius casuarius)

Native to: Tropical rainforests of Papua New Guinea, Indonesia and northeastern Australia
Height: 1.5-1.8 meters
Weight: 17-70 kilograms
Life span: About 30 years in the wild, 18-50 years in captivity
Eats: Mostly fruit that has fallen onto the ground, also fungi, snails, small dead mammals
Can I eat it? No. The IUCN classifies them as Vulnerable, and they are listed as Endangered in Australia.
You should know: The males are smaller, incubate the birds’ large green eggs and rear the chicks.
What should I do if I encounter one? Leave it alone. If you’re lucky, the bird will just ruffle its feathers and hiss at you. If not, it will attack. And that could be very bad. Its innermost claw is elongated and very sharp. The last known case of death by southern cassowary was back in 1926, but there have been plenty of instances of broken bones and gashed bodies.

Northern cassowary (Casuarius unappendiculatus)
Northern cassowary sarsifa/Flickr (CC BY-NC-SA 2.0)

Native to: Parts of Indonesia and Papua New Guinea
Height: 1.5-1.8 meters
Weight: males 27-30 kilograms, females 58 kilograms
Life span: 18-20 years in the wild, 40 years in captivity
Eats: Fruit and small animals
Can I eat it? Locals capture young cassowaries and raise them for meat, but you probably shouldn’t eat them. There are only some 2,500 to 10,000 in the world, and the IUCN classifies them as Vulnerable, largely because of the threat of hunting.
You should know: All species of cassowaries play an important role in their ecosystems by distributing the seeds of the fruits they eat.
What should I do if I encounter one? Leave them alone. Like the southern cassowary, these birds are armed with nasty claws.

Dwarf Cassowary (Casuarius bennetti)

Native to: Papua New Guinea
Height: 1-1.5 meters
Weight: 17.6-26 kilograms
Life span: Unknown
Eats: Fallen fruits, insects, small mammals
Can I eat it? Dwarf cassowaries are hunted as food, but the IUCN says their numbers are decreasing. Probably best to leave them be.
You should know: They can swim across rivers.
What should I do if I encounter one? Again, leave it alone. Like the other cassowaries, these birds know how to defend themselves with their powerful, clawed feet.

Greater rhea (Rhea americana)

Native to: Brazil, Argentina, Bolivia, Paraguay and Uruguay
Height: 1.5 meters, though males can stand 1.8 meters tall
Weight: 20-27 kilograms, though large males may be as heavy as 40 kilograms
Life span: 10.5 years
Eats: Foliage, seeds, fruit, insects, rodents, reptiles, small birds
Can I eat it? Yes. They are raised in farms for their meat and leather.
You should know: Cougars and jaguars eat greater rheas.
What should I do if I encounter one? Keep your distance. Like their ratite relatives, rheas are armed with sharp claws. And males are particularly protective of their young, lashing out even against female rheas.

Darwin’s rhea (Rhea pennata)
Darwin’s rhea Kristofor & Rebekah/Flickr (CC BY-NC-SA 2.0)

Native to: Argentina
Height: About 1 meter
Weight: 15-29 kilograms
Life span: Not specified
Eats: Mostly saltbush and cactus fruits. Also grasses and small animals.
Can I eat it? Technically yes, but you probably shouldn’t. Their numbers have been decreasing, in part due to hunting and egg collecting. They are considered uncommon, particularly two northern subspecies whose populations may number in the hundreds.
You should know: The species is named after Charles Darwin, who fruitlessly searched for one of the birds for months after hearing about them from gauchos in Patagonia. He finally found the elusive bird when artist Conrad Martens shot a rhea for a meal. Only then did Darwin realize that the bird was the one he had been searching for, and he managed to preserve parts for scientific study.
What should I do if I encounter one? Leave it alone.

Big Bird (Bigus canarius)
Big Bird Igel B TyMaHe/Wikimedia Commons

Native to: A large nest behind 123 Sesame Street
Height: 2.5 meters
Weight: As “light as a feather,” according to Big Bird himself
Age: About 6 and a half
Eats: His favorite food is birdseed.
Can I eat it? No! How could you even think of such a thing?
You should know: One of his pet peeves is chicken soup.
What should I do if I encounter one? Give him a hug.

Sarah Zielinski is the Editor, Print at Science News Explores. She has a B.A. in biology from Cornell University and an M.A. in journalism from New York University. She writes about ecology, plants and animals.

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