Abstract
The endangered south-eastern Red-tailed Black-Cockatoo (RtBC), an Australian bird, relies largely on habitat on private agricultural land. The remaining population of about 1400 individuals is threatened by the loss of habitat trees, which are removed to allow agricultural intensification, particularly centre-pivot irrigation. We sought to investigate alternative future scenarios of habitat tree availability for the RtBC across its range, focusing on the most depleted resource, mature Buloke trees. We aimed to 1) identify the current extent and condition of RtBC Buloke habitat resources; and 2) model how resource availability might change in the future under different land management scenarios. In particular, we sought to evaluate the likely impact of proposed 'offset' measures, where permits to remove trees are only granted with the condition that either new trees are planted in their place, or that other mature trees are protected. Large old trees were identified as critically important for the RtBC, highlighting the importance of strategies to reduce high tree death rates through changes to land management practices such as burning of crop stubbles. Scenarios based on current trends resulted in a further loss of about 35% of mature Buloke trees within 100 years. Scenarios where the clearing of large mature trees required the protection of several other mature trees as an offset reduced this loss to about 25%, depending on the improvement in survival of 'protected' trees. The conservation of the species will require a joint effort by private land managers and policy makers to reduce rates of loss of mature trees on farmland.