#rheidae

Lesser Rhea (Rhea pennata)

Darwin's rhea (Rhea pennata), family Rheidae

Also known as the lesser rhea, it is the smaller of the two species of rhea. Together they are the only extant species within their family.

Renowned Rheas

A distant cousin to the ostrich and the emu, rheas or ñandus are a group of birds belonging to the genus Rhea, consisting of the common rhea ( Rhea americana) and the lesser rhea (Rhea pennata). Also included as either a subspecies or a seperate species is the puna rhea ( Rhea tarapacensis). This group is found in the southern half of South America, typically in open grasslands or sparse woodlands.

Like their flightless relatives, rheas are large, flightless birds characterised by a small head, long neck, and long legs. Adults of the common rhea species can reach up to 1.5 m (4 ft 11 in) tall and 27 kg (60 lbs), while the smaller species only reach 1 m (39 in) and 29 kg (63 lbs). All members of the rhea group have dull grey or brown coloration. Males are typically larger than females, although both possess large clawed feet which are used for outrunning or out-kicking predators like cougars (Puma concolor) and pampas cats ((Leopardus colocolo), which often go after nests or chicks.

Rheas are largely herbivorous, and spend most of their days grazing. Their diets consist of grass, cacti, saltbrush, and the occasional small lizard or insect. Outside the breeding season they can be found in flocks of 10-100, with individuals taking turns watching for potential threats while the others graze. During the breeding season, from July to January, males fight each other with their sharp claws and beaks to gain dominance. The victor mates with up to 12 females, each of which produces a clutch of 20-40 eggs each season.

 Once the eggs are laid, the males provide all the care for the offspring. These eggs are laid once every 48 hours, and most are moved to a nest for protection. However, some eggs are left to rot, and the flies they attract serve as food for the brooding males and their chicks. Eggs take about 30 days to hatch, and the young are taken are of for an additional six months. Rhea fathers are extremely territorial, and will become aggressive even towards other females, all while guarding several broods of chicks. Once they reach independence at six months old, chicks join a group of young adults, though they don’t become sexually mature until they’re about two years old. In captivity individuals can live up to 13 years.

Conservation status: The greater rhea is considered Near Threatened by the IUCN, while the lesser rhea is classified as Least Concern. Their main threats are habitat destruction and increased hunting and nest poaching from humans.

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Photos

Dave Curtis via eBird

Konrad Wothe

Lesser Rhea (Rhea pennata)

Lesser rhea (Rhea pennata)