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Home , Greater rhea, Rhea (bird)

GREATER RHEIFORMES : : Rhea : americana

Range: Lowlands to 2000 meters in , , , , and ; northeastern Brazil southward to Argentina : grassy plains () and sparse woodlands Niche: Terrestrial, omnivorous, diurnal Wild diet: grass, roots, , with some , nuts, ( and caterpillars) and small such as lizards. Zoo diet: diet Life Span: (Wild) 15 yrs. (Captivity) Sexual dimorphism: males slightly larger and darker than females Location in SF Zoo: Puente al Sur

APPEARANCE & PHYSICAL ADAPTATIONS:

The is a ratite and the largest in the Americas. It has brown or gray upper parts and whitish underparts. They have long powerful legs and can use their feet to kick at a potential predator but prefer to outrun them. Although their large wings are useless for flight, they are used for balance and for changing direction as the bird runs. As rheas run, reaching Weight: 80 lbs speeds of 37 mph, they spread their wings out to act as sails and their long neck is almost horizontal to the ground. When in danger they flee in a zig-zag Height: 3 - 5 ft course, utilizing first one wing then the other, similar to a rudder. They have a strong claw on each wing, which can be used as an effective weapon. They are good swimmers.

Rheas have excellent eyesight and good hearing allowing them to detect predators from far away. Rheas are distinguished from by their three-toed feet, their lack of fine plumes, and their brownish color as well as their head, neck and thighs being feathered.

STATUS & CONSERVATION

The greater Rhea population in Brazil has been severely reduced through hunting and habitat destruction, but because species is still common in parts of Bolivia and Argentina, it is not yet considered threatened.

They have been hunted for years for feathers and . A permit is need for any importation or exportation, because they are on the CITES list, which means they are endangered. Rhea are collected for food along with the meat. Their skins are used in the manufacture of leather, and hunting to supply this trade has thinned their numbers considerably. Today, regulations have limited both hunting and farming rhea for these commercial uses.

COMMUNICATION AND OTHER BEHAVIOR

Tend to be silent with the exception being when they have chicks or when the male is seeking a mate. The male makes a deep resounding “bu-up” or “nan-du” primarily during courtship. Males are solitary in the spring breeding season, but in winter, rheas are social and flock together in groups of 10 to 100 birds. Rheas frequently congregate with deer or guanacos, and form mixed herds. During breeding season these flocks break up with the females separating off into small groups while the males become territorial. When being chased a rhea can out run their predator but has a habit of retracing their steps, suddenly squatting down amongst the bushes and flattening their body against the ground to go unnoticed. They will eat pebbles to help with their digestion.

COURTSHIP AND YOUNG

Greater rheas are polygamous; males have many different mates and do not form lasting pairs. Each male defends a large territory and tries to attract a harem of 2 to 12 females to mate with him. As a nest, he makes a hollow in the ground and he alone is in charge of incubating the eggs. The females can deposit up to 15 eggs in the same nest. The male will utilize a decoy system and place some eggs outside the nest and sacrifice these to predators. Once the females have laid their eggs, they may move on and mate with other males. The male rhea incubates the eggs of all its mates for six weeks and cares for the newly hatched young for an additional 5 mos. Once the first chick hatches and starts calling, this stimulates the other eggs to all hatch within 24 - 28 hours.

Males are often very aggressive, especially during breeding season, and will fiercely defend their territory, eggs, and young. They defend their nest by lowering their heads and hissing, often grasping each other's . They will even charge at a female rhea, which may approach the chicks. During breeding season they have a prominent black ring at the base of their neck that extends downward like a stain.

Incubation: 6 weeks Sexual Maturity: 2 years # of eggs: 13 – 30 eggs Weight at birth:

MISCELLANEOUS

The name Ratite means ‘keel less".

There are 2 species of rhea. The Lesser or Darwin's Rhea, Rhea pennata, is mostly found in the southern part of from southward to . The Darwin's Rhea, which is considered an endangered species is somewhat smaller, its brownish plumage is tipped with white and lays a pale green .

Sources: Created: 1/2012 Handbook of the Birds of the World, Volume 1 © 1992 Lynx Edicions, pgs 84 – 89. The Princeton Encyclopedia of Birds © 2004 Christopher Perrins, Princeton University Press, p 38-49 http://animals.nationalgeographic.com/animals/birds/greater-rhea/