ntsthatareknowntoberichinthem.Clearly,theanimalsmustbegettingsomethingelseoutofeatingearth.Thecurrentbeliefisthatsoil-andparticularlytheclayinit-helpstodetoxifythedefensiveposionsthatsomeplantsproduceinanattempttopreventthemselvesfrombeingeaten.Evidenceforthedetoxifyingnatureofclaycamein1999,fromanexperimentcarriedoutonmacawsbyJamesGilardiandhiscolleaguesattheUniversityofCalifornia,Davis,Macawseatseedscontainingalkaloids,agroupofchemicalsthathassomenotoriouslytoxicmemberssuchasstrychnine.Inthewild,thebirdsarefrequentlyseenperchedonerodingriverbankseatingclay.DrGillardifedonegroupofmacawsamixtureofaharmlessalkaloidandclay,andasecondgroupjustthealkaloid.Severalhourslater,themacawsthathadeatentheclayhad60%lessalkaloidintheirbloodstreamsthanthosethathadnot,suggestingthatthehypothesisiscorrect.
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