Some riverbanks with exposed clay in the Amazon rainforest are favorite destinations for various parrot species to supplement their sodium intake.
Parrots in the Amazon rainforest have a particular affinity for clay. They gather in large numbers along riverbanks to peck at the clay, creating a vibrant spectacle that attracts thousands of viewers. But why do they exhibit this peculiar behavior?
Red-and-green macaws eating clay in the Amazon rainforest. (Photo: Jorgeluizpsjr).
One of the most widely accepted hypotheses is that parrots are deficient in sodium in their diets. Sodium is essential for various bodily functions, including nerve impulse transmission, maintaining electrolyte balance, heart function, and several metabolic processes. Many herbivorous species that consume a plant-based diet require additional salt (which contains sodium) because plants do not provide sufficient salt. Consequently, animals often obtain sodium from salt licks. Clay and soil serve as excellent sources of sodium and other nutrients such as potassium and magnesium.
Another hypothesis suggests that parrots consume clay to eliminate toxins from plants from their bodies. When birds ingest clay, the clay particles bind with natural toxins such as quinine and tannic acid, preventing them from being absorbed through the digestive tract.
However, research indicates that the sodium hypothesis is more accurate. The Tambopata Research Center (TRC) in Peru studied the clay-eating behavior of parrots at clay licks in Peru and found that the areas of clay chosen by the birds did not exhibit higher toxicity absorption compared to the unselected parts of the clay lick. Instead, the birds preferred clay with higher sodium content.
At a clay lick along a bend in the Manu River, researchers observed that parrots particularly favored a layer of clay that extended hundreds of meters along this bend. They avoided eating the layers above and below. This layer was found to have significantly higher sodium levels than the surrounding areas.
Parrots gathering at a clay lick in the Tambopata National Reserve, Peru. (Photo: Salparadis).
Donald Brightsmith, the leader of the Tambopata Macaw Project, points out that parrots outside the western Amazon region also consume food containing toxins, such as the seeds of the sandbox tree (Hura crepitans). However, only those in the western Amazon visit clay licks. This suggests that parrots might tolerate a small amount of toxins in their stomachs without needing clay for detoxification.
Instead, Brightsmith believes there is a connection between this clay-eating habit and the particular deficiency of salt in the western Amazon region. Research by Alan Lee, a specialist at Manchester Metropolitan University, and colleagues supports this finding. According to their study, the behavior of parrots eating clay is significantly related to the distance from the sea, indicating that nutrient deficiency rather than food toxins is the primary driver of this behavior.
There are dozens of locations where parrots gather to eat clay in Paraguay, Peru, Bolivia, Brazil, and Ecuador within the Amazon rainforest, but the most popular and accessible spots are located in the Tambopata National Reserve in southeastern Peru. Other well-known sites where people can observe this unique phenomenon include the Blanquillo clay lick in Manu National Park, Peru, and Yasuni National Park, Ecuador.
