 A yellow @-@ tailed black cockatoo was observed stripping 4 cm × 2 cm ( 1 @.@ 57 in × 0 @.@ 79 in ) pieces of bark off the trunk of a dead Leptospermum tree in Acacia <unk> swamp near <unk> in northwestern Tasmania . It then scraped a layer of white material about 0 @.@ 5 mm thick from the inner surface with its beak . This white layer turned out to be <unk> fungi and slime mould that grew in the cambium of the bark . 
