Something like this happened recently in QLD, I'm thinking it was Mornington Island but can't quite remember, perhaps that was where they diverted?
Due to a large fire nearby there were reportedly "Hundreds" of Birds flocking around the Airport creating quite a hazard and causing a few diversions.
Felt it was a good personal reminder to always allow a bit of extra fuel whenever you can, mother nature has weird ways of trying to catch us out that can't be predicted.