The Atacama Desert is an expansive plateau along the Pacific coast of South America, primarily within northern Chile. Stretching over a 1,600-kilometer strip, it is widely recognized as the driest non-polar desert on Earth, with some areas receiving less than a few millimeters of rainfall annually. Its extreme aridity is caused by a rain shadow from the Andes Mountains and the cooling effect of the Humboldt Current, which prevents Pacific moisture from reaching the land. This context of intense heat and minimal precipitation sets the stage for a unique ecosystem where only specialized life forms can persist.
Adapting to Hyper-Aridity
Survival requires physiological and behavioral strategies to conserve water. Many small mammals and insects adopt a nocturnal lifestyle, becoming active after sunset to avoid scorching daytime temperatures and reduce evaporative water loss. Burrowing, or fossorial habits, is a common adaptation, as underground microclimates are significantly cooler and more humid than the surface.
Desert mammals have evolved kidneys with an elongated Loop of Henle, which allows for the creation of extremely concentrated, or hyperosmotic, urine. This maximizes the reabsorption of water, minimizing fluid loss when waste is excreted. Other species, particularly small rodents, rely almost entirely on metabolic water, produced internally as a byproduct of breaking down food like dry seeds.
A remarkable local adaptation is the reliance on camanchaca, the dense coastal fog that rolls in from the ocean. While the hyper-arid central desert receives almost no rain, the coastal hills, known as lomas, intercept this fog. Specialized organisms, including certain spiders and insects, are found in these fog zones, obtaining their moisture directly from the condensation. This moisture also sustains the sparse vegetation that serves as a food source for these invertebrates.
Mammals and Reptiles of the Central Desert
The terrestrial fauna of the central, hyper-arid plains and lower mountain slopes consists of species that embody drought resistance. Among the most noticeable mammals are the South American camelids, the Guanaco (Lama guanicoe) and the Vicuña (Vicugna vicugna), both relatives of the llama. Guanacos are found in slightly more arid areas and can survive for longer periods without fresh water.
The Vicuña, prized for its fine wool, typically remains near areas where grass is irrigated by melted snow or steady water sources. The South American grey fox (Lycalopex griseus), or Culpeo fox, is an omnivorous predator. It hunts smaller prey like rodents and lizards, but also supplements its diet with fruit and seeds. The ability to consume a varied diet is a major survival advantage in this resource-scarce environment.
Small rodents like Darwin’s leaf-eared mouse (Phyllotis darwini) acquire all their necessary moisture from the insects and seeds they eat. Reptiles are represented by several species of lava lizards and Liolaemus lizards, which are cold-blooded and can thermoregulate by basking on rocks or retreating into crevices. One species, Liolaemus fabiani, is specifically adapted to the extreme conditions of the Atacama salt flats.
Birds and Amphibians of High-Altitude Wetlands
While the central desert is sparsely populated, localized, water-rich ecosystems exist, particularly in the high-altitude Andes known as the Altiplano. Salt flats (salares) and permanent high Andean lagoons, such as Miscanti and Miñiques, are fed by snowmelt and support a unique, dense concentration of life. These wetlands are internationally recognized for their populations of flamingos.
Three species of flamingos—the Chilean (Phoenicopterus chilensis), Andean (Phoenicoparrus andinus), and James’s (Phoenicoparrus jamesi)—congregate in these mineral-rich waters. They feed on microscopic algae and brine shrimp, which gives their feathers their characteristic pink color. Although the Andean flamingo is the rarest species, it is often the most abundant in specific lagoons like Laguna Chaxa.
Other specialized birds include the Puna Rhea (Rhea pennata tarapacensis), a large, flightless bird, and the Horned Coot, which nests in the Miscanti and Miñiques lagoons. The Atacama toad (Rhinella atacamensis), a rare amphibian, is restricted to the lomas and coastal wetlands. It relies entirely on temporary or permanent pools to lay its eggs, demonstrating the delicate balance of life in these isolated pockets of moisture.