Macaws are a group of New World parrots that are long-tailed and often colorful, in the tribe Arini. They are popular in aviculture or as , although there are conservation concerns about several species in the wild.
Proportionately larger beaks, long tails, and relatively bare, light-coloured medial (facial patch) areas distinguish macaws from other parrots. Sometimes the facial patch is smaller in some species and limited to a yellow patch around the eyes and a second patch near the base of the beak in the members of the genus Anodorhynchus. A macaw's facial feather pattern is as unique as a fingerprint.
The largest macaws are the Hyacinth macaw, Buffon's (great green) and green-winged macaws. While still relatively large parrots, mini-macaws of the genera Cyanopsitta, Orthopsittaca and Primolius are significantly smaller than the members of Anodorhynchus and Ara. The smallest macaw species, the red-shouldered macaw, is no larger than some parakeets of the genus Aratinga.
Macaws, like other , and , are zygodactyl, having their first and fourth toes pointing backward.
International trade of all macaw species is regulated by the CITES (CITES). Some species of macaws—the scarlet macaw ( Ara macao) as an example—are listed in the CITES Appendix I and may not be lawfully traded for commercial purposes. Other species, such as the red-shouldered macaw ( Diopsittaca nobilis), are listed in Appendix II and may legally be traded commercially provided that certain controls are in place, including a non-detriment finding, establishment of an export quota, and issuing of export permits.
Aviculturists have reported an over-abundance of female blue-and-yellow macaws in captivity, which differs from the general rule with captive macaws and other parrots, where the males are more abundant. This would explain why the blue and gold is the most commonly hybridised macaw, and why the hybridising trend took hold among macaws. Common macaw hybrids include the harlequin ( Ara ararauna × Ara chloroptera), miligold macaw ( Ara ararauna × Military macaw) and the Catalina macaw (known as the rainbow in Australia, Ara ararauna × Scarlet macaw). In addition, unusual but apparently healthy intergeneric hybrids between the hyacinth macaw and several of the larger Ara macaws have also occasionally been seen in captivity. Macaws, Hybrid Names, and pages on individual hybrids. Another, much rarer, occurrence of a second-generation hybrid (F2) is the miliquin macaw (harlequin and military macaws).
Some foods eaten by macaws in certain regions in the wild are said to contain toxicity 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 Macaw Society, located at the Tambopata Research Center (TRC) in Peru, has studied the clay eating behaviour 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 absorb 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 greater than 100 kilometres from the ocean. The distribution of clay licks across South America further supports this hypothesis – as the largest and most species-rich clay licks 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 behaviour by macaws is not seen outside the western Amazon region, even though macaws in these areas consume some 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 clay licks 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 the breeding season.Brightsmith, D. J. 2006. "The psittacine year: what drives annual cycles in Tambopata's parrots?" Proceedings of the Loro Parque International Parrot Symposium, Tenerife, Spain. 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.
Another theory is that the birds, as well as other herbivorous animals, use the clay licks as a source of cobalamin, otherwise known as vitamin B12.
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