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About This GigapanToggle
- Taken by
- Jeff Cremer
- Explore score
- 0.51 Gigapixels
- Date added
- Dec 28, 2010
- Date taken
- Dec 28, 2010
Nikon D80 + Nikon 200-400mm f/...
Macaws eat a variety of foods including fruits, palm fruits, nuts, seeds, leaves, flowers, and stems. Wild species may forage widely, over 100 km (62 mi) for some of the larger species such as Ara araurana (blue & yellow macaw) and Ara ambigua (great green macaw), in search of seasonally available foods. Some foods eaten by macaws in the wild contain toxic or caustic substances which they are able to digest. It has been suggested that parrots and macaws in the Amazon basin eat clay from exposed river banks to neutralize these toxins. In the western Amazon hundreds of macaws and other parrots descend to exposed river banks to consume clay on an almost daily basis - except on rainy days.
Donald Brightsmith, the principal investigator of the Tambopata Macaw Project, located at the Tambopata Research Center (TRC) in Peru, has studied the clay eating behavior of parrots at clay licks in Peru. He and fellow investigators found that the soils macaws choose to consume at the clay licks do not have higher levels of cation exchange capacity (ability to adsorb toxins) than that of unused areas of the clay licks and thus the parrots could not be using the clay to neutralize ingested food toxins. Rather, the macaws and other bird and animal species prefer clays with higher levels of sodium. Sodium is a vital element that is scarce in environments >100 kilometers from the ocean. The distribution of claylicks across South America further supports this hypothesis - as the largest and most species rich claylicks are found on the western side of the Amazon basin far from oceanic influences. Salt-enriched (NaCl) oceanic aerosols are the main source of environmental sodium near coasts and this decreases drastically farther inland.
Clay-eating behavior by macaws is not seen outside the western Amazon region even though macaws in these areas consume toxic foods such as the seeds of Hura crepitans, or sandbox tree, which have toxic sap. Species of parrot that consume more seeds, which potentially have more toxins, do not use claylicks more than species that eat a greater proportion of flowers or fruit in their diets.
Studies at TRC have shown a correlation between clay lick use and breeding season. Contents of nestling crop samples show a high percentage of clay fed to them by their parents. Calcium for egg development - another hypothesis - does not appear to be a reason for geophagy during this period as peak usage is after the hatching of eggs.