Threatened cockatoo adapts foraging strategy to survive habitat loss from fire

Fire regimes are changing across the globe as a result of human‐induced climate change. For granivorous bird species, changes in fire regimes can affect seed availability and the persistence of populations. We investigated the foraging behaviour of Glossy Black Cockatoos Calyptorhynchus lathami halmaturinus , a resource specialist, following large‐scale severe wildfires that occurred during the 2019–20 Australian Black Summer and burnt more than 80% of habitat in some affected flock regions. On Kangaroo Island, endangered Glossy Black Cockatoos feed exclusively on Allocasuarina verticillata (sheoak) seed and are known to have strong preferences, driven by food profitability, when choosing feeding trees. We estimated foraging intensity per feeding patch at 54 natural (remnant) and revegetated foraging habitat sites over three time periods in 2023–24, of which 30 sampling sites were in flock regions with greater than 50% burnt habitat and 24 in less than 50% burnt habitat. We collected cones from 380 foraged trees at 39 of these sites to determine Clout's Index (a measure of food value), and assessed the association between foraging intensity, Clout's Index and a range of environmental variables, including fire impact, habitat age and rainfall. The probability of a tree being foraged was significantly higher in feeding patches in burnt regions (47%), compared to regions less impacted by the fires (27%). Higher foraging intensity did not reflect the cone profitability of foraged trees, with no significant difference in Clout's Index of foraged trees between burnt and unburnt flock regions. Higher values for Clout's Index, a measure of cone profitability, were associated with younger revegetation sites and remnant habitat sites in the highest rainfall areas. The carrying capacity of Glossy Black Cockatoo feeding habitat on Kangaroo Island was estimated at around 600 birds during the post‐fire habitat recovery period. Available feeding habitat post‐fire was well below calculated requirements for long‐term survival and breeding in fire‐impacted flock regions. Protection of remaining foraging habitat from fire and strategic revegetation could help to prevent further reductions to carrying capacity. Given predictions of increasing fire and drought in southeastern Australia, urgent action may be required to manage future impacts on this and other threatened habitat specialists.