Time since fire influences food resources for an endangered species, Carnaby’s cockatoo, in a fire-prone landscape

Abstract

Where threatened species persist in multiple use landscapes, management activities, such as prescribed burning, may influence the availability of resources for those species. We examined how time since fire can influence food resources for the endangered Carnaby’s cockatoo (Calyptorhynchus latirostris) in banksia woodlands of southwestern Australia. Tree density and cone productivity of dominant plant species, Banksia attenuata and Banksia menziesii, were compared across 44 sites of varying post-fire aged vegetation. The number of Carnaby’s cockatoos that could be supported in banksia woodlands was estimated using the bird’s energetic requirements and seed energy content. Banksia attenuata produced more cones at sites aged 10–30years since fire in both survey years, while cone productivity for B. menziesii was highest in very old sites (>35years since fire) in one year only. Higher numbers of Carnaby’s cockatoos were predicted to be supported in vegetation aged between 14–30years since fire, peaking in vegetation aged 20–25years. The current distribution of post-fire aged vegetation within this area (>60% burnt within the last 7years) is predicted to support ∼2725 Carnaby’s cockatoos, representing 25–35% of the estimated birds reliant on the area. Our results indicate that food resources are influenced by time since fire and, consequently, if optimising food resources was an objective, may be manipulated by altering burning patterns. While human and asset protection is a priority for prescribed burning, management of landscapes for improved persistence of threatened species is also important and complex trade-offs will have to be considered.