Rainbow Lorikeets stripping bark off trees.

[scouler <>]

On 21st August, 2004, I was with a group of other birdwatchers in wet sclerophyll forest in Excelsior Park  Nature Reserve in Baulkham Hills, a north-western suburb of Sydney. We were intrigued by the behaviour of two Rainbow Lorikeets. They were perching vertically on the trunk of a very large eucalypt ( a blackbutt, as I recall), and using their beaks to pull off small pieces of bark from the trunk. They were quite persistent in this behaviour, keeping it up for minutes at a time and returning to it, after flying off a short way.

Opinions varied amongst the group as to what the RLs were up to. As far as we could tell, they were not swallowing the bits of bark, but were dropping them after passing them through their beaks.  Nor they did seem to be carrying any of the bark away. Some of the group suggested that they were after insects under the bark (though we did not see them extract anything from under the bark). Somebody else suggested that the RLs might have been gathering the bark to line a nest hollow, and would return later to collect the bark which they had dropped to the ground.

I consulted HANZAB later, but did not come up with a definitive explanation. HANZAB says that RLs feed mainly on nectar and pollen from flowers, and also fruit, seeds and occasionally insects. I'd hazard a guess that most of the insects would be "bycatch", ingested incidentally in the course of feeding on flowers and fruit. I doubt if RLs would go after insects under the bark of trees, a quest for which they are singularly ill-equipped.  HANZAB does mention a detailed study by observation of the feeding habits of Rls in ne NSW and se Qld, which recorded that they obtained about 4% of their food from "bark, insects and bread and honey" The bark was apparently from a species of paperbark, Melaleuca quinquenerva.

I couldn't find any support in HANZAB for the suggestion that the RLs  might have been collecting nesting material.

Can any birdwatchers and/or aviculturalists shed any light on the RLs' behaviour?

Regards,
Colin Scouler.