The seriemas are the sole extant members of the small and ancient clade Cariamidae, which is also the sole surviving lineage of the Cariamae group. Once believed to be related to cranes, they have been placed by one recent study near the falcons, parrots and passerines, as well as the extinct terror birds.^[1] The seriemas are large, long-legged terrestrial birds that range from 70 to 90 cm. They live in grasslands, savanna, dry woodland and open forests of Brazil, Bolivia, Argentina, Paraguay and Uruguay. There are two species of seriesmas, the Red-legged Seriema (Cariama cristata) and the Black-legged Seriema (Chunga burmeisteri).^[2] Names for these birds in the Tupian languages are siriema, sariama, çariama, which are explained as meaning "crested" (New Shorter Oxford English Dictionary).

Description

Both species are around 80 cm (31 in) long; the Red-legged Seriema is slightly bigger than the Black-legged. They forage on foot and run from danger rather than fly (though they can fly for short distances, and they roost in trees). They have long legs, necks, and tails, but only short wings, reflecting their way of life. They are brownish birds with short bills and erectile crests, found on fairly dry open country, the Red-legged Seriema preferring grasslands and the Black-legged Seriema preferring scrub and open woodland. They give loud, yelping calls and are often heard before they are seen. The have sharp claws, with an extensible and very curved second toe claw.^[2]

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  The Black-legged Seriema (Chunga burmeisteri) is smaller and have a more restricted distribution.

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  The frontal crest of the Red-legged Seriema (Cariama cristata) is unique among Neotropical birds.

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  The seriemas have short wings and rarely take flight.

Behaviour and ecology

Ecologically they are the South American counterpart of the Secretary Bird. They feed on insects, snakes, lizards, frogs, young birds, and rodents, with small amounts of plant food (including maize and beans). They often associate with grazing livestock, probably to take insects the animals disturb. When seriemas catch small reptiles, they beat the prey on the ground (Redford and Peters 1986) or throw it at a hard surface to break resistance and also the bones. If the prey is too large to swallow whole, it will be ripped into smaller pieces with a sickle claw by holding the prey in the beak and tearing it apart with the claw.

Reproduction

Seriemas build bulky stick nests. They lay two or three white or buff eggs sparsely spotted with brown and purple. The female does most of the incubation, which last from 24 to 30 days. Hatchlings are downy but stay in the nest for about two weeks; then they jump down and follow both parents. They reach full maturity at the age of four to five months.

Taxonomy and systematics

Idiornis tuberculata fossil

There are two species of seriemas, the Red-legged Seriema, or Crested Cariama ( Cariama cristata) that is found from eastern Brazil, to central Argentina. It is bigger and nests on the ground or in bushes or trees up to 3 m (9.8 ft) above the ground. In the other hand, the Black-legged Seriema ( Chunga burmeisteri) is found in northwest Argentina and Paraguay. It nests in trees.

The two extant species of seriema are thought to be the closest living relatives of a group of gigantic (up to 10 ft/3.0 m tall) carnivorous "terror birds", the phorusrhacids, which are known from fossils from South and North America.^[3][4] Several other related groups, such as the idiornithids and bathornithids were part of Palaeogene faunas in North America and Europe and possibly elsewhere too.^[3][4] However, the fossil record of the seriemas themselves is not good, with a single prehistoric species (Chunga incerta) having been described to date. Some of the fossils from the Eocene fauna of the Messel Pit (i.e. Salimia and Idiornis) have also been suggested to be seriemas,^[5] though their status remains uncertain.

References