Multi-decadal habitat and fire effects on a threatened bird species

Abstract

Quantifying factors influencing the occurrence of species is a core component of ecology and conservation biology. A key part of understanding occurrence patterns is identifying suitable habitat and how suitability may change over time, including in response to perturbations like wildfires. Such understanding requires long-term studies that track species occurrence over prolonged periods in response to multiple disturbances. In this study we combined: (1) 19-years of Eastern Bristlebird (Dasyornis brachypterus) site occupancy data from 109 sites at Booderee National Park, with (2) long-term data on fire history, and (3) detailed spatial information on vegetation cover. Our data showed an increase in site occupancy by the Eastern Bristlebird since 2002, indicating efforts to conserve the species should be regarded as a conservation success. However, it remains possible that the persistence of the species is conservation dependent and a function, in part, of ongoing feral predator control. We found heathlands were the preferred habitat, with bristlebirds occupying most heathland sites. Woodlands and sedgelands were moderately suitable habitat, with forests and rainforests rarely occupied. There was evidence of a strong spatial effect of heathland, with woodland and sedgeland sites near heathland more likely to be occupied. This suggests an influence of landscape mosaics, with birds possibly spilling over from preferred habitats to less preferred places. The Eastern Bristlebird appears to respond differently to fire than other bird taxa in our study region and park management practices like prescribed burning may need to consider the needs of a range of species. The results of our investigation highlight the importance of long-term studies to underpin evidence-based biodiversity conservation in fire-prone vegetation types and landscape mosaics.