Thiamine Deficiency and Winter Mortality in Red Wattlebirds, Anthochaera Carunculata (Aves:Meliphagidae) in Surburban Melbourne.

Abstract

Red wattlebirds are found in convulsions during winter in south-eastern suburbs of Melbourne, and eventually die. We suggest that the birds suffer from a thiamine deficiency. The symptoms of the sick birds-head retraction, convulsions and anorexia-are similar to those described for animals with a thiamine deficiency, and the diet of wattlebirds is likely to be low in thiamine, particularly in winter. Furthermore, thiamine levels in the blood of convulsing birds were significantly lower than those in healthy birds and similar to levels that induce clinical symptoms in humans. Thiamine levels of healthy birds showed a seasonal pattern and were lowest in winter, suggesting a thiamine shortage during winter. However, we were unable to induce the symptoms when caged birds were fed on a thiamine-deficient diet. The high ambient temperatures used during these feeding trials may have prevented clinical symptoms from developing. Further work is needed before firm conclusions can be made about the role of thiamine deficiency in the winter mortality of red wattlebirds.