Researchers in Queensland have made significant progress in understanding the effects of dispersal on flying fox colonies.
Biosecurity Queensland’s principal scientist Dr Hume Field said the 12-month research project by the Queensland Centre for Emerging Infectious Diseases assessed the impact of colony dispersal on stress and Hendra virus infection levels in affected flying foxes.
Hendra is a virus carried by fruit bats in Australia. It is able to be passed to horses and on rare occasions can be passed from horses to human. Four of the seven reported cases in people have proved fatal.
“A key finding of the project found there was no association between the disturbance to a colony from dispersal and an increase in the excretion of Hendra virus,” Field said.
“Researchers measured the stress hormones and virus levels in flying foxes by collecting and testing urine before, during and after the dispersal of a colony.
“Transmitters were also attached to flying foxes to track their movements by satellite, and showed that flying foxes did not stay in the one colony, but regularly moved from colony to colony.
“Of the 13 colonies monitored – 10 in Queensland, three in New South Wales – 10 were dispersed or disturbed as a result of the submission of a Damage Mitigation Permit.”
In Queensland, colony dispersal may occur only after a comprehensive assessment is completed by the Department of Environment and Heritage Protection and under a Damage Mitigation Permit.
Field said the study provided scientific evidence that disturbed colonies typically had measurable, short-lived stress of a similar level to that seen with natural stress events such as mating.
“Research also highlighted that Hendra virus excretion was much less in little red flying foxes and in grey-headed flying foxes,” Field said.
“The level of Hendra virus excretion was found to be higher in black and spectacled flying-foxes, suggesting these species may be a more important source of infection for horses than the little red or grey-headed flying foxes.”
Field said the research was commissioned by National Hendra virus Research Program in 2011 to investigate any association between colony dispersal, stress and Hendra virus excretion.
The National Hendra Virus Research Program is funded by the Commonwealth of Australia, and the states of New South Wales and Queensland.
“Studies will continue to clarify the role of flying fox species, the role of environmental factors, and the role of horse behaviour in the transmission of Hendra virus from flying foxes to horses,” Field said.