Habitat loss for black flying foxes and implications for Hendra virus

Abstract

Context: Environmental change impacts natural ecosystems and wildlife populations. In Australia, native forests have been heavily cleared and the local emergence of Hendra virus (HeV) has been linked to land-use change, winter habitat loss, and changing bat behavior.

Objectives: We quantified changes in landscape factors for black flying foxes (Pteropus alecto), a reservoir host of HeV, in sub-tropical Queensland, Australia from 2000-2020. We hypothesized that native winter habitat loss and native remnant forest loss were greatest in areas with the most human population growth.

Methods: We measured the spatiotemporal change in human population size and native 'remnant' woody vegetation extent. We assessed changes in the observed P. alecto population and native winter habitats in bioregions where P. alecto are observed roosting in winter. We assessed changes in the amount of remnant vegetation across bioregions and within 50 km foraging buffers around roosts.

Results: Human populations in these bioregions grew by 1.18 M people, mostly within 50 km foraging areas around roosts. Remnant forest extent decreased overall, but regrowth was observed when policy restricted vegetation clearing. Winter habitats were continuously lost across all spatial scales. Observed roost counts of P. alecto declined.

Conclusion: Native remnant forest loss and winter habitat loss were not directly linked to spatial human population growth. Rather, most remnant vegetation was cleared for indirect human use. We observed forest loss and regrowth in response to state land clearing policies. Expanded flying fox population surveys will help better understand how land-use change has impacted P. alecto distribution and Hendra virus spillover.

Supplementary information: The online version contains supplementary material available at 10.1007/s10980-023-01642-w.

Keywords: Deforestation; Habitat loss; Hendra virus; Pteropus.

Fig. 1

Study area. a Australia, denoting the state of Queensland. b All bioregions of Queensland with bioregions of interest shaded in grey. c Labeled bioregions of interest showing roosts occupied in winter by black flying foxes with green dots and 50 km buffers representing Northern and Southern Foraging areas denoted in purple and blue buffers, respectively

Fig. 2

Areas of Human Population Growth 2000-2020 and Proximity to Roosts used by Black Flying foxes. a Bioregions of interest showing human population growth between 2000 and 2020 in dark purple pixels with Northern and Southern foraging areas outlined in purple and blue, respectively, and three red boxes identifying areas important for Hendra virus spillover are shown in panels (b-d). b Close up of Mackay, QLD, c close up of Rockhampton, QLD, d close up of Brisbane, QLD. For b-d, areas of human population growth are shown in dark purple, roosts occupied by black flying foxes during winter in green dots, and HeV spillovers in yellow triangles

Fig. 3

Change in Extent of Remnant Forests and Woody Vegetation in Bioregions of Interest 2000-2019. a Hectares lost or gained from the previous time point of woody vegetation in the bioregions important for black flying foxes. b Net change in woody vegetation from 2000 to 2019 by bioregion

Fig. 4

Extent Change of Winter Habitats for Black Flying Foxes and Homogenous Patch Loss Dynamics 1999-2019. Hectares lost or gained from the previous time point of VMRE maps colored by bioregion. a Extent change of possible winter habitats in bioregions of interest from 1999-2019. b Extent change of possible winter habitats for Northern and Southern foraging areas in 50 km around roosts from 2011-2019. c Extent loss of possible winter habitat homogenous patches binned by the proportion of the patch that was lost from 1999-2019. d Number of homogenous winter habitat patches that lost area, or were impacted by clearing, binned by the proportion of the patch that was lost from 1999-2019

Fig. 5

Observed Black Flying Fox Populations in the National Flying Fox Monitoring Program by Bioregion and Hendra Virus Spillovers. a Proportion of observed black flying fox roost counts seen in each bioregion from 2007 to 2021 with darker shades of grey representing a greater percentage of the total observed population, hatched cells representing no survey data, and circles denoting year and bioregion of HeV spillover events. b Number of black flying foxes observed in each bioregion by season since 2012. Filled circles represent the year and number of Hendra virus spillover events; size of circles corresponds to the number of confirmed horse cases. c Cumulative number of Hendra virus horse cases in each bioregion and state of New South Wales since detection with the grey box denoting the period shown in (a). d Bioregions of interest with roosts occupied by black flying foxes in winter as yellow dots; inset map of eastern Australia shows Queensland’s bioregions of interest and the state of New South Wales