Editing Macaw (section)

== Diet and clay licks ==
[[File:Parrots at a clay lick -Tambopata National Reserve, Peru-8c.jpg|thumb|right|upright|Macaws and [[Southern mealy amazon]]s at a clay lick in Tambopata National Reserve, Peru]]

Macaws eat a variety of foods including seeds, nuts, fruits, palm fruits, leaves, flowers, and stems. Safe vegetables include asparagus, beets, bell peppers, broccoli, butternut, carrots, corn on the cob, dandelion greens, collard greens, hot peppers, spinach, sweet potatoes, tomatoes and zucchini. Wild species may forage widely, over {{convert|100|km|0|abbr=on}} for some of the larger species such as ''Ara araurana'' (blue and yellow macaw) and ''Ara ambigua'' (great green macaw), in search of seasonally available foods.

Some foods eaten by macaws in certain regions in the wild are said to contain [[toxicity|toxic]] or [[corrosive substance|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.<ref>{{cite thesis|title=Ecology of Parrots in the Peruvian Amazon: Habitat Use, Nutrition, and Geophagy|last1=Gilardi|first1=James D.|year=1996|type=Ph.D.|publisher=University of California at Davis|location=Davis, California}}</ref> In the western Amazon hundreds of macaws and other parrots descend to exposed river banks to consume clay on an almost daily basis<ref>{{Cite journal|last=Munn|first= C. A. |date=January 1994|title= Macaws: winged rainbows|journal= National Geographic|volume=185|issue=1|pages=118–140}}</ref> – except on rainy days.<ref>{{cite journal|last=Brightsmith|first= D. J.|year= 2004|title=Effects of Weather on Parrot Geophagy in Tambopata, Peru|issue=2 |volume= 116|journal=The Wilson Bulletin|pages= 134–145|jstor=4164648|doi=10.1676/03-087b|s2cid= 83509448|url= https://www.biodiversitylibrary.org/part/209843}}</ref> 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<ref>{{cite journal|last1=Brightsmith |first1= Donald J.|last2= Muñoz-Najar|first2= Romina Aramburu|title= Avian Geophagy and Soil Characteristics in Southeastern Peru|journal= Biotropica |volume=36 |issue=4 |pages= 534–543|doi=10.1111/j.1744-7429.2004.tb00348.x|year= 2004|bibcode= 2004Biotr..36..534B}}</ref> 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.<ref>{{cite journal|doi=10.1111/j.1744-7429.2009.00514.x| volume=41|issue=3|pages=279–282| title=Parrots Take it with a Grain of Salt: Available Sodium Content May Drive ''Collpa''(Clay Lick) Selection in Southeastern Peru| journal=Biotropica| year=2009| last1=Powell| first1=Luke L.| last2=Powell| first2=Thomas U.| last3=Powell| first3=George V. N.| last4=Brightsmith| first4=Donald J.| s2cid=86506489| doi-access=free| bibcode=2009Biotr..41..279P}}</ref> Sodium is a vital element that is scarce in environments greater than 100 kilometres from the ocean.<ref>{{cite journal|doi=10.1073/pnas.0804528105|title=On the biogeography of salt limitation: A study of ant communities |journal=Proceedings of the National Academy of Sciences |volume=105 |issue=46 |pages=17848–17851 |year=2008 |last1=Kaspari |first1=M. |last2=Yanoviak |first2=S. P. |last3=Dudley |first3=R. |bibcode=2008PNAS..10517848K |pmid=19004798 |pmc=2584704|doi-access=free }}</ref> 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.<ref>{{cite journal|doi=10.1111/j.1600-0587.2009.05878.x|pages= 503–513|title= Parrot claylick distribution in South America: Do patterns of 'where' help answer the question 'why'?|journal= Ecography|year= 2009|last1= Lee|first1= Alan T. K.|last2= Kumar|first2= Sunil|last3= Brightsmith|first3= Donald J.|last4= Marsden|first4= Stuart J.|volume=33|issue= 3}}</ref> Salt-enriched ([[NaCl]]) oceanic aerosols are the main source of environmental sodium near coasts and this decreases drastically farther inland.<ref name=Lee>{{cite thesis|last=Lee|first= A. T. K.|year= 2010|url=http://macawproject.org/index.php/reports-theses-and-conference-papers/viewdownload/10-reports-theses-and-conference-papers/62-parrot-claylicks-distribution-patterns-of-use-and-ecological-correlates-from-a-parrot-assemblage-in-southeastern-peru |title=Parrot Claylicks: Distribution, Patterns of Use and Ecological Correlates from a Parrot Assemblage in Southeastern Peru|type= Ph.D. |publisher=Manchester Metropolitan University}}</ref>

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.<ref name=Lee />

Studies at TRC have shown a correlation between clay-lick use and the breeding season.<ref>Brightsmith, D. J. 2006. [http://site.perunature.com/Research2/Brightsmith_Parrot_annual_patterns_in_Tambopata_2006.pdf "The psittacine year: what drives annual cycles in Tambopata's parrots?"] {{Webarchive|url=https://web.archive.org/web/20150906220132/http://site.perunature.com/Research2/Brightsmith_Parrot_annual_patterns_in_Tambopata_2006.pdf |date=2015-09-06 }} Proceedings of the Loro Parque International Parrot Symposium, Tenerife, Spain.</ref> Contents of nestling [[Crop (anatomy)|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 B<sub>12</sub>.