Fire-mediated tree cavity reduction needs to be considered in reintroduction strategies for a critically endangered bird

Abstract

Fire is an important agent of tree cavity creation and loss in some forest ecosystems. Even though cavity-bearing trees may be replaced over decades post fire, cavity-nesting animals depend on uninterrupted access to suitable nesting sites. Balancing the impacts of fire on the availability and recruitment of suitable tree cavities for wildlife is important. We studied fire effects on trees with suitable nests for Critically Endangered Orange-bellied Parrots Neophema chrysogaster to evaluate how to optimize suitable cavity availability both now and into the future. We used field surveys to quantify the age-class distribution of trees across the species' historical range, and climbed them to reveal that only 16% of Smithton peppermints Eucalyptus nitida supported a potentially suitable nest cavity. We incorporated this information into a simulation that explored the impacts of fire on the occurrence of nest trees over a century under different fire regimes. We predicted that more frequent and severe fires resulted in lower probabilities of persistence of nesting sites for Orange-bellied Parrots. Management of the foraging habitat of Orange-bellied Parrots requires regular burning of moorlands adjacent to the forests where they nest. Our simulations show that preventing regular burning of these forests is important to maximize the probability of persistence of nesting habitat for Orange-bellied Parrots. We show that by incorporating field data on the true availability of habitat, it is possible to simulate the uncertain impacts of fire on future perpetuation of suitable nesting cavities for wildlife.