Lesser Rhea

The Lesser Rhea, also known as Darwin's Rhea, is a flightless ratite adapted to the cold, open steppe and high-altitude grasslands of southern South America, including Patagonia and the high Andean puna. Smaller and hardier in cold climates than its relative the Greater Rhea, it is well suited to some of the continent's harshest open habitats.

Like other rheas, it lives in flocks, runs at considerable speed to escape predators, and follows a breeding system in which males incubate a shared clutch of eggs from multiple females and raise the chicks alone.

• Body plumage is soft and loose in structure, similar to other rheas, lacking interlocking flight-feather barbules
• Overall color is mottled grayish-brown, with many feathers tipped in white or pale buff, creating a speckled or frosted appearance
• Underparts are paler than the back, with the speckled pattern extending across the flanks
• Wings are reduced and non-functional for flight, as in the Greater Rhea, used for balance and display
• Distinguished from the Greater Rhea by smaller overall size and the presence of fine pale speckling across the plumage, versus the more uniform grayish-brown of the larger species

Adults of both sexes show similar mottled, pale-speckled grayish-brown plumage, without the strong sexual dimorphism seen in some other rheas. Chicks are downy with a striped gray-and-buff pattern for camouflage on open ground, gradually developing the mottled adult plumage over their first year. There is no pronounced seasonal plumage change in this species.

The Lesser Rhea inhabits open steppe, arid grassland, and high-altitude puna habitats across Patagonia and the high Andes of Argentina, Chile, Bolivia, and Peru. It is a resident species well adapted to cold, wind-swept, and high-elevation open country, generally remaining within its home range year-round.

This species feeds on grasses, seeds, and small invertebrates, foraging by walking steadily across open terrain. As with the Greater Rhea, males build a ground nest, incubate eggs contributed by several females, and raise the resulting chicks alone. Lesser Rheas rely on strong running speed and vigilance to avoid predators in open habitat, and vocalizations are generally limited to booming calls given by males during the breeding season.