Darwin’s Rhea
Taxonomy
■ Phylum: Chordata – chordates
■ Class: Aves – birds
■ Clade: Palaeognathae – ratites
■ Order: Struthioniformes – ostriches and relatives
■ Family: Rheidae – rheas
■ Species: Rhea pennata – Darwin’s Rhea
Conservation
Distribution and habitat
Lesser rhea inhabits South American open shrubland and steppe of Patagonia and on the Andean plateau.
Adaptions
Lesser rhea on average is 120 cm tall and a weight about 30 kg.
Rhea has powerful legs and can reach a running speed of 60 km/h. During the run it stretches its neck horizontally and keeps its wings close to its body. Like ostriches and emus, the knee joint is forward oriented – that is opposite to humans.
Rhea’s subtle colours are used to hide from predators. Unlike most birds the males and females are very difficult to tell apart. Adults are brownish grey to chestnut, but chicks have yellowish-white colour and acquire the mottling of the adults at the age of one.
Rheas’ thick and soft feathers protect them from elements. Rhea is a flightless bird, but it uses its wings to court females and incubate eggs.
Rhea is a social species, that out of breeding season forms groups of around 30 birds.
Diet
Lesser rhea is herbivorous, feeding mainly on salt bushes and cactus fruits, as well as grasses, roots, seeds and leaves. But, if given the chance, rhea will occasionally eat small animals like lizards, beetles, grasshoppers.
Breeding
During breeding season, the male makes a simple nest on the ground and multiple females lay their eggs near it. The male is responsible for collecting and incubating them.
A single nest can have around 18-20 eggs and incubation lasts 40 days. During this time males are very aggressive, even defending the nest against females.
Soon after hatching chicks are ready to follow the male that takes care of them for for 6-9 months until they become independent. Occasionally rhea males will also adopt abandoned chicks and take care of them.
The young rheas are ready to mate at the age of 3.
Conservation and threats
The main threats to rheas are hunting and egg collection for food and traditional medicine. Additionally, their habitats are suffering from fragmentation and conversion to farmlands.
References:
Baldi, R., Pirronitto, A., Burgi, M. V., & Antún, M. (2015). Abundance estimates of the lesser rhea Rhea pennata pennata in the Argentine Patagonia: conservation implications. Frontiers in Ecology and Evolution, 3, 135.
Del Hoyo, J., Del Hoyo, J., Elliott, A., & Sargatal, J. (1992). Handbook of the birds of the world (Vol. 1, No. 8). Barcelona: Lynx edicions.
Pedrana, J., Bustamante, J., Travaini, A., Rodriguez, A., Zapata, S., Martínez, J. I. Z., & Procopio, D. (2011). Environmental factors influencing the distribution of the Lesser Rhea (Rhea pennata pennata) in southern Patagonia. Emu-Austral Ornithology, 111(4), 350-359.
IUCN https://www.iucnredlist.org/species/22678081/217016710
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