Hemochromatosis, or iron storage disease, is a condition wherein iron absorption is not properly regulated; over time, too much of the mineral is stored in the liver and other organs. Most commonly seen in captive mynas, it also crops up in other fruit-eaters, including toucans, lorikeets and other parrots. During my tenure at the Bronx Zoo, several birds-of-paradise came down with the disease.Oranges and other citrus fruits are often identified as contributing to the disease’s onset. Prompted by a recent blog comment, I’d like to address the matter in this article.
The Citrus Connection
Citrus fruit is a potential concern because ascorbic acid renders the iron in plant foods more biologically available, and hence easier to store. In general, the iron in plants is not readily available to birds, but that in bananas, raisins and grapes is an exception to this rule…these too should be avoided where appropriate.
Research and Theories
Research on the issue has led to somewhat conflicting results. Birds maintained on low iron diets have come down with the disease, while over-supplementation of iron has led to liver lesions indicative of hemochromatosis in some but not all experiments.
One interesting school of thought proposes that populations of birds living on iron poor diets in the wild may develop unusually effective iron storage abilities, leaving them prone to the disease when fed typical captive diets. This might explain why mynas and others vary in their iron tolerances.
In humans, folic acid and choline deficiencies seem to pre-dispose one to iron storage disease…further research is needed here as well.
What to Do
Many generations of mynas, birds of paradise and other species have been bred without incident on diets containing moderate amounts of citrus fruits, so at this point the matter begs more research. Perhaps the iron levels in commercial softbill pellets should be investigated more closely.
Those who are unsure should consult their veterinarians…radiographs and blood tests can disclose liver problems, which may be indicative (but not diagnostic) of hemochromatosis, and can help to point one towards a healthful diet.
Dietary Variety for Frugivores
Frugivorous birds do best when provided with a wide variety of tropical fruits and some vegetables – not an easy task in certain seasons and locations. Please check out our extensive line of freeze-dried fruits and vegetables, including mango, raspberries, papaya, sweet potatoes, peas and others, for some ideas.
For information on growing your own fruits, flowers and other bird foods, please see my article Gardening for Birds.