The danger of grapes - a rumination

[BeatriceC]

Hot damn! ,can't wait to see what MrC finds. Fascinating discussion even if likely started under incorrect assumptions

Being a scientist and all, he's thorough and will take his time. Give him a couple hours. Though he's currently digging looking for relevant information.

 

[Kentuckienne]

I've read the same as Loko concerning mycotoxin. It was in regards to meerkats at a zoo rolling their grapes in clay before eating them. Clay is used in naturopathy to make poisons and toxins inert. The purpose of ingestion of soil and minerals in wild parrots is believed by many researchers to nullify the many toxins in the seeds and nuts which comprise the majority of a parrot's diet. Plants try to deter predation of their unripe seeds and nuts by using some sort of physical deterrent (hard shell, spikes) or chemical deterrent (caustic, toxic, or bitterness). When their seeds or nuts are ripe, many plants encourage animals to eat their seeds so they'll spread them in their feces by offering fragrant, sweet, colourful fruit, or by losing or weakening the physical or chemical defences that they were using to protect the unripe seeds. Parrots feed on unripe seeds and nuts, using their powerful beaks to crush the hardest of shells (i.e., macaws, cockatoos), and are able to withstand the toxins in the unripe seeds/protective outer flesh that would cause other animals to become violently ill or leave them with chemical burns. Obviously I'm not suggesting to give captive birds such foods, as they don't have access to the same nullifying compounds that wild parrots have access to.

Same as Dinosrawr was saying. Plus, you've gotta remember that parrots can eat the hottest of peppers without getting gut rot, further supporting not just the use of detoxifying and nullifying compounds, but also physiology.

Hey, Billdore, as far as pesticide concerns go, I'd start buying from health food stores. At my local one at least, all their produce is certified organic, so you don't have to worry about transference.

While looking up a plant described as good for birds, unearthed a passel of scholarly articles, for some the accepted belief that birds eat clay to neutralize poisons is not correct, no correlation - some birds eat poisons and no clay, some eat clay but no poisons, consensus forming that it has more to do with the salt content of the clays. More salt, more eat.

 

[Teddscau]

My info comes from "Parrots of the Wild", https://www.highlightskids.com/science-stories/parrots-eat-dirt, and http://www.10000birds.com/the-macaws-of-tambopata-peru.htm. Salt may be a factor in some cases, but the neutralization of poisons through geophagy is often leaned towards. Also, just because not all parrots consume clay does not mean those who do eat clay don't do so for dealing with toxins. Some birds roll around in ant hills, while others don't, but just because some birds don't doesn't mean bathing in ant hills...okay I'm trying to say that some birds roll in ant hills to deal with lice and other parasites. The fact that not all birds do this doesn't mean that...you know what I mean.

I'm not knocking what you're saying about salt, though.

 

[Kentuckienne]

The problem with collecting information online is that I get more confused. The anecdotal facts - things everyone knows are true - far outnumber the evidence-based studies. I found a "scholar" option in Google that cost me so many hours of wading through nerdy stuff, which I confess I enjoy, being pretty nerdy stuff myself. Here are some of the references I thought especially interesting, concerning macaws and the clay licks:

Smithsonian Why Do Hundreds of Macaws Gather at These Peruvian Clay Banks? | Travel | Smithsonian

(Argues for the sodium hypothesis)

Also, from the Wikipedia entry for macaws:
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Some foods eaten by macaws in certain regions in the wild are said to 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.[11] In the western Amazon hundreds of macaws and other parrots descend to exposed river banks to consume clay on an almost daily basis[12] – except on rainy days.[13] Donald Brightsmith, the principal investigator of the Tambopata Macaw Project, 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[14] 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.[15] Sodium is a vital element that is scarce in environments greater than 100 kilometres from the ocean.[16] 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.[17] Salt-enriched (NaCl) oceanic aerosols are the main source of environmental sodium near coasts and this decreases drastically farther inland.[18]

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.[18]

Studies at TRC have shown a correlation between clay-lick use and the breeding season.[19] 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.

 

[DRB]

IIRC the deal with grapes is kidney failure.