Movement Ecology of the Black Flying Fox (Pteropus alecto) in a Changing Landscape: Implications for Hendra Virus Spillover in Eastern Australia
Historically nomadic, black flying foxes (Pteropus alecto) traveled hundreds of kilometers across the landscape in search of seasonally ephemeral plant food resources. Land clearing has decreased native habitat of P. alecto in coastal eastern Australia and increased seasonal variability in native food sources, driving flying foxes into continuously-occupied roosts in and around urban areas. As a natural host for Hendra virus, understanding P. alecto movement is critical to understanding Hendra virus and its transmission and spillover dynamics. High densities of smaller roosts, along with consistent resources temporally, led us to hypothesize that bats in urban roosts would forage closer to the roost sites than previously recorded for bats at non-urban roosts. However, we expected that bats would exhibit seasonally variable movements, especially as native resources are increasingly unavailable in winter months. We investigated foraging distances, track tortuosity, and foraging ranges, by tracking 76 adult P. alecto from two continuously occupied roosts using GPS-GSM trackers. One roost is in a highly urbanized area, and the other is in a peri-urban area, adjacent to native habitat. We collected 883 bat-nights of tracking data (722 foraging nights and 161 roost-switching nights) throughout 2019–2021. Although we observed occasional extreme nightly movements (up to 218.27 km), most nightly foraging distances and maximum displacement calculations from the roost were comparatively short (mean 7.0 ± 5.0 km). Bats travelled longer distances when foraging from the peri-urban roost, with individual mean track lengths ranging from 8.7 – 51.6 km compared to 3.7 – 44.4 km at the urban roost. Bats from the urban roost predominantly foraged locally in developed areas, whereas bats from the peri-urban roost displayed a mixed foraging strategy, exploring developed, agricultural, and native landscapes. Understanding foraging movements of urban resident flying foxes can help prevent human-wildlife conflicts and promote coexistence in and around increasingly urban environments. Insight into how the movement ecology and foraging behaviors of P. alecto could affect Hendra virus spillover and dynamics in this system could also further help us understand other zoonotic diseases globally.
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