Environmental drivers of spatiotemporal foraging intensity in fruit bats and implications for Hendra virus ecology

John R Giles,Raina K Plowright,Hamish Mccallum,Hazel Parry,Peggy Eby,David A Westcott,Alison J Peel

doi:10.1038/s41598-018-27859-3

Abstract

In the Australian subtropics, flying-foxes (family Pteropididae) play a fundamental ecological role as forest pollinators. Flying-foxes are also reservoirs of the fatal zoonosis, Hendra virus. Understanding flying fox foraging ecology, particularly in agricultural areas during winter, is critical to determine their role in transmitting Hendra virus to horses and humans. We developed a spatiotemporal model of flying-fox foraging intensity based on foraging patterns of 37 grey-headed flying-foxes (Pteropus poliocephalus) using GPS tracking devices and boosted regression trees. We validated the model with independent population counts and summarized temporal patterns in terms of spatial resource concentration. We found that spatial resource concentration was highest in late-summer and lowest in winter, with lowest values in winter 2011, the same year an unprecedented cluster of spillover events occurred in Queensland and New South Wales. Spatial resource concentration was positively correlated with El Niño Southern Oscillation at 3–8 month time lags. Based on shared foraging traits with the primary reservoir of Hendra virus (Pteropus alecto), we used our results to develop hypotheses on how regional climatic history, eucalypt phenology, and foraging behaviour may contribute to the predominance of winter spillovers, and how these phenomena connote foraging habitat conservation as a public health intervention.

Highlights

In 1930, frustration with the depredations of flying-foxes on commercial orchards led the Australian Government to commission an English researcher, Francis Ratcliffe, to undertake the first systematic investigation into the biology and ecology of pteropod bats [colloquially known as ‘flying-foxes’1]
GHFF foraging ecology is important because it plays a central ecological role in the health of eucalypt forests and in patterns of bat-borne disease dynamics, which are both major concerns for conservation strategies
Model selection criteria based on performance within the 5-fold spatial cross validation structure returned 27 models giving the mean Poisson deviance and Mean Squared Error (MSE) (Table 1)

Summary

Introduction

In 1930, frustration with the depredations of flying-foxes on commercial orchards led the Australian Government to commission an English researcher, Francis Ratcliffe, to undertake the first systematic investigation into the biology and ecology of pteropod bats [colloquially known as ‘flying-foxes’1]. Management typically included destroying bats and roosts[2] Motivated by these antagonistic interactions, Ratcliffe sought to understand flying-fox ecology in order to direct better-informed management strategies at that time. Pteropids throughout the Old World pollinate numerous species of hardwood trees[11] This role is especially crucial in Australia because eucalypt forests have considerable economic value as timber and they are primarily animal pollinated [i.e. mammals, birds, and insects12]. In contrast to this important ecosystem service, Australian flying-foxes are known reservoirs of Hendra virus. Eucalypt forests within the range of GHFF can exhibit variable spatiotemporal patterns in phenology depending on local species richness, climate, and environment

Methods

Results

Conclusion