136 AUSTRALIAN FIELD ORNITHOLOGY 2008, 25 , 136–139 Little and Long-billed Corellas Learning to Use a New Food Source, the Seeds of Marri ALLAN H. BURBIDGE Department of Environment and Conservation, P.O. Box 51, Wanneroo, Western Australia 6946 (Email:
[email protected]) Summary . It has been shown that corellas Cacatua spp. are not capable of breaking open the larger, woody capsules of eucalypts to feed on the enclosed seeds. However, since being introduced to south-western Australia, both Long-billed C. tenuirostris and Little Corellas C. sanguinea have learnt to extract the large seeds of Marri Corymbia calophylla by modifying their feeding behaviour to tip out the seeds of the open capsules into the bill. Few birds eat eucalypt seeds, with some obvious exceptions being the Red- capped Parrot Purpureicephalus spurius and the black-cockatoos Calyptorhynchus spp. of south-western Australia (Woinarski et al . 1997). In particular, it is well known that these species feed on the seeds of Marri Corymbia calophylla , formerly Eucalyptus calophylla . (Both Eucalyptus and Corymbia species are hereinafter referred to as ‘eucalypts’, for ease of reference and because much of the literature on eucalypts refers to all of the previously recognised subgenera of Eucalyptus as ‘eucalypts’). Marri, which is common and widespread in south-western Australia, has hard, woody capsules (locally called ‘honky nuts’), measuring up to ~5 cm long and up to ~3.5 cm in diameter. Baudin’s Black-Cockatoo Calyptorhynchus baudinii extracts the seeds with its long upper mandible, causing little damage to the seed-capsules, Carnaby’s Black-Cockatoo C.