Rhea americanagreater rhea

Geographic Range

The common rhea lives in south-eastern part of South America.

Habitat

Rheas live in pampas, campos, cerrado and open chaco woodland of South America. They avoid open grassland. Rheas live in areas with at least some tall vegatation. During the breeding season, they stay near rivers, lakes, or marshes.

Physical Description

Largest South American bird, flightless, unmistakeable due to its great height, massive legs, and terrestrial habits.

  • Average mass
    23 kg
    50.66 lb

Reproduction

Their breeding season is from August to January, depending on the region. Males court two to twelve females. Once mating has occurred, the males build nests, which are shallow holes in the ground with a rim that is surrounded by twigs and vegatation. Each of the females lay one egg in the male's nest every other day for a period of seven to ten days. After the first two or three days of egg laying, the male stays with his nest and eggs and begins incubating them. A male usually incubates ten to sixty eggs. The chicks hatch within thirty-six hours of each other. The male takes care of the chicks by himself. Female rheas move from male to male throughout the breeding season.

Behavior

During the spring, male rheas are solitary, and females form into small groups. Yearlings form a flock until they are two years old, which is when they are ready to breed. At the end of the summer males, females, and chicks come together to form large flocks for the winter months. The flocks formed after the breeding season contain twenty to thirty and sometimes as many as one hundred rheas.

Communication and Perception

Food Habits

Rheas are omnivorous, preferring broad-leaved plants and clover. However, they eat a variety of seeds, roots and fruits. They also eat insects, including grasshoppers; small vertebrates, such as lizards, frogs, small birds and snakes. Rheas continuously move as they feed.

Economic Importance for Humans: Positive

Rhea feathers are used to make feather dusters in South America. Their skins are used for leather, their meat and eggs are consumed by man and dogs.

Economic Importance for Humans: Negative

Rheas are a pest to farmers because they will eat almost any agricultural crop.

Conservation Status

The rhea population has declined considerably and is considered to be near threatened. In 1980, over 50,000 skins were traded; however a permit is now needed for their export and import. Rheas and their eggs are eaten by local people. They are also killed to be used as dog food. Rhea chicks are threatened by many predators. The rhea's habitat has become limited due to agricultural progress. Rheas are eliminated near agricultural areas, because they will eat almost any crop.

Other Comments

Rheas cannot fly. However, they have unusually long wings for flightless birds. They use their wings like an airplane rudder, in order to help them dodge predators. When male rheas are taking care of their young, they will charge at female rheas and humans who come to close to the chicks. Cowboys working near rheas take dogs with them to divert or discourage the male's charge.

Contributors

Maija K. Schommer (author), University of Michigan-Ann Arbor.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chaparral

Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.

chemical

uses smells or other chemicals to communicate

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

scrub forest

scrub forests develop in areas that experience dry seasons.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5? N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

References

Perrins, Dr. Christopher M. & Dr. Alex L.A. Middleton, eds. 1985. The Encyclopedia of Birds. Facts on File Publications, New York. pgs. 21-24.

del Hoyo, J., A. Elliott & J. Sargatal, eds. 1992. Handbook Of The Birds Of The World, Vol 1. Lynx Ediciones, Barcelona. pg. 89.

Grzimek, Dr. Dr. h.c. Bernard, ed. 1972. Grzimek's animal Life Encyclopedia, Vol 7, Birds. Van Nostrand Reinhold Company, New York. pg. 89-91.