The impact of fire on the quality of drooping sheoak (Allocasuarina verticillata) cones for the endangered Kangaroo Island glossy black-cockatoo (Calyptorhynchus lathami halmaturinus)

The Kangaroo Island glossy black-cockatoo (Calyptorhynchus lathami halmaturinus) is an endangered subspecies that feeds almost entirely on the kernels of drooping sheoak (Allocasuarina verticillata). Hence, it is highly susceptible to changes in the quantity or quality of A. verticillata. Fire has the potential to severely impact glossy black-cockatoo feeding habitat on the island, but since A. verticillata is serotinous, it is partially reliant on fire for regeneration. Here, we quantified the effects of time-since-fire (over a 60-year period) on cone quality for C. lathami halmaturinus. Cone quality in A. verticillata woodlands with a range of fire histories was examined using three measures of cone profitability: the ratio of seed-to-cone mass (Clout’s Index), the ratio of kernel-to-cone mass (Kernel Ratio) and the proportion of seeds containing kernels (Seed Fill). We then mapped the fire history of A. verticillata woodlands on Kangaroo Island before and after the 2019/20 bushfire season. We found that time-since-fire had a significant negative impact on Clout’s Index, as well as a negative but non-significant impact on Seed Fill and Kernel Ratio. This suggests that trees that have not experienced fire in over 60 years may have cones that are of lesser value to C. lathami halmaturinus. This is concerning, because up to 94% of A. verticillata woodlands not impacted by the 2019/20 bushfires are likely of a similar age class, having had no fire in over 60 years. Our findings highlight the need for ongoing assessment and management of critical habitat for this endangered subspecies