ARE FLYING FOXES THE MENACE THAT WE THINK THEY ARE?
The year 2001 has been a bad year for flying foxes - especially for the grey-headed flying fox, found from Maryborough to Melbourne, and for the spectacled flying fox, found from Cardwell to Cooktown. Not that the commoner black and little red flying foxes have escaped attention either.
Communities from Mataranka Springs to Mareeba to Mullumbimby to the Melbourne Botanic Gardens have declared war on these animals, drumming them out of their traditional roost sites, as well as shooting them and burning their colonies. A major fruit grower in the Cardwell area is being hailed into court on the grounds that he killed from 12,000 to 20,000 animals in December last year, during the peak of the lychee season. QNPWS are effectively on trial with them him for issuing Damage Control licenses after the event rather than doing their duty to protect a protected species.
Why this sudden upsurge in anti-flying fox activity?
Well - first of all, flying foxes have similar tastes to humans for living space - river views, shady groves of trees, lots of nice nectar and fruit trees nearby. Such real estate near towns and cities is getting scarce, so developers are sub-dividing flying fox habitat that until fairly recently would have been rejected as "swampy". With the growth of the sugar and coastal beef industry, land that would have been considered marginal coastal paperbark swamps that are prime feeding areas for flying foxes, have been cleared - often in an unnoticeable piecemeal fashion, putting pressure on the flying foxes to do their shopping in town.
While these activities are nothing new and have been going on for a long time, the occurrence of human deaths from bat-related viral infections really started the high levels of anti-bat activity that we have seen over the past 5 years.
The first was the death of the horses and trainers from bat-morbilli virus, later re-named bat paramyxovirus. This virus is common in flying foxes, and manifests itself as a flu-like infection, particularly in birthing mothers. It doesn't infect humans - many tens of thousands of birthing flying foxes have been handled by researchers and carers with absolutely no record of cross-infection. However it did infect horses - giving them a very severe form of pneumonia. Their trainers were "super-infected" by the horses and died. Researchers at the Geelong Laboratory for Animal Health have since tried every method of infecting horses (and other animals) from flying foxes, and failed. We can only assume that the virus "sero-converted" and became infective.
After that died down, the popular status of flying foxes was dealt another blow - this time by the tragic death of an animal rescuer in Rockhampton. This time the virus was much worse, it was lyssa-virus, a member of the rabies family.
Never mind that the virus in this case, did not in fact come from a flying fox, but from a microbat, a yellow-bellied sheath-tailed bat, one of the sort that you see at dusk chasing mosquitoes. However, the discovery of the virus completely upset Australia's image of itself as "rabies-free". Needless to say, all newspaper articles featured pictures of flying foxes with banner headlines reading "Killer Bat Kills Mother of 2".
Following closely on that was an attack on a woman in a park by a flying fox, which did have lyssa virus, and the woman died (after being offered and refusing anti-rabies anti-serum). Now this time the virus did come from a flying fox. So the press and the animal health authorities had a field day - offering free rabies inoculations to animal workers and draconian measures for animals that were even faintly suspected of having interacted with un-inoculated members of the public.
Two more recent viral outbreaks also were blamed on flying foxes -both involving pigs - the Menangle virus in NSW and the Nipah virus of Malaysia. Mutterings were heard about the dreaded Ebola (Haemorrhagic fever) virus of central Africa being bat-transmitted. This has not proved to be the case.
The conservation stocks of flying foxes by this time had sank to an all time low, as calls went out to the relevant authorities to remove the animals from towns and other human habitation, for fear "they'd kill us all".
Now time has passed, researchers are starting to accept that lyssa virus has been in the flying fox and microbat populations for thousands of years, and that it rarely transmits to humans. The timing of this particular grouping of new viral infections has been particularly unfortunate, as these viruses are rare in wild flying fox populations - probably in the range of 1 in 10,000 to 25,000 and can be considered similar to being dealt 4 aces in a poker hand. Highly unlikely, but it does happen. However, the general public has not been brought up to speed with this information. In the past, many thousands of flying foxes have been rescued and rehabilitated, and some few have had lyssa virus ("snappy-bats") and have bitten carers - yet no one else has died of lyssa virus - again, because like bat para-myxo virus, it doesn't cross-infect easily.
Over the past 300 years, bats have developed a fearsome reputation in European cultures, and been associated with the powers of darkness and evil. Flying foxes, because of their size and the fact that they fly at dusk, really engender this reaction in some people. Yet Asian cultures regard bats as good luck symbols, and incorporate them into designs - the bird-like figures in rice-grain chinaware, are bats.
The discovery of the world's only blood-lapping microbats (vampire bats) in Mexico by Columbus, coupled with real human rabies outbreaks in Central European Transylvania, giving rise to the Dracula legends (which had nothing to do with bats), undeservedly gave bats a bad name in European culture, and this was brought to Australia with the European settlement.
So, along with the Dingo, the Thylacine, the Wedge-tailed eagle, flying foxes joined the ranks of Australian animals that must be exterminated because of a perceived conflict with our pastoral interests.
In 1932, the Australian Government contracted a British biologist, Francis Ratcliffe, to visit and, among other things, to come up with a permanent solution to the depredations that flying foxes were thought to be making on farmers' orchards. Ratcliffe, after surveying flying fox colonies from NSW to northern Queensland, came to the conclusion that flying foxes did relatively minimal damage to orchards, and that birds were far more damaging. Besides, he concluded that flying foxes were (then) so numerous and so part of the natural system that attempts to exterminate them would be futile. Live and let live. At the time of Ratcliffe's visit, flying fox numbers were in the millions, and camp sizes of an estimated half million (for the big flying foxes, not little reds) were common.
Now, the estimated populations of grey headed flying foxes is about 1/4 million and spectacled flying foxes, half that.
There has been a massive collapse in numbers. Why?
Firstly, loss of habitat - all the sugar cane once was either rainforest, or dry or paper-bark forests, all of it feeding habitat for flying foxes and many other animals as well.
Loss of colonies accounts for another major source of loss - colonies in the not-so-distant past have been gassed with cyanide, burned, shot and plain bulldozed out of existence. In the Cairns area alone, some five major spectacled flying fox colonies were expunged in the last 20 years, and in the northern wet tropics, some 27 colonies have been wiped out, leaving only about twenty. Even the colony in the Cairns central swamp has had numerous attempts made to destroy it, before it was declared protected.
Secondly, they are very slow recruiters - they do not "breed like rats", as popular belief would have us know. Flying foxes are related to us - in fact they are flying lemurs - the early primates (that look a bit like brush-tail possums) found in Madagascar. Being primates, they aren't born pre-programmed with all the behaviours that they need for survival. (Later data showed they are not primates; they are related to the microbats - Editor, 2011.)
They have a 3-year adolescence in which to learn these skills, before they are properly sexually mature, and have their first baby. Baby, singular. Rarely, if ever, twins (and one of the pair always dies).
Pregnancy takes 6 months, weaning occurs 6 months later, after which the juvenile enters the care of the colony for the next 2½ years, - to learn to be a flying fox. In captivity, flying foxes can live to over 20 years. In the wild, we suspect that neither the spectacled nor the grey headed flying fox chalks up too many years past six. Major reductions in population (such as colony burning or use of Fyre Foxes - an electrocution system for protecting orchards) become increasingly difficult for the flying fox colonies to overcome and then suddenly, crash, it's all over and they are extinct. It can happen very fast.
So - why would that matter? Well, firstly, they have a major role in the bush as pollinators of a wide range of trees - not just ordinary pollinators like bees, but long-range pollinators, that is the pollinators that spread the genes around, and prevent the formation of small, isolated populations of trees that succumb to the effects of sustained interbreeding. Flying foxes can travel several tens of kilometres between feed trees each night. Researchers have found that the health of the SE Eucalypt forests in NSW/Victoria are maintained by grey headed flying foxes.
Spectacled flying foxes play a similar role for rainforest trees in the wet tropics, and the black and little red flying foxes for trees in the drier and more northerly environments.
Secondly, for large-seeded trees, they disperse seeds - often disperse seeds - often many hundreds of metres away from the parent tree. Other animals cannot perform this service to the plant. Think of the thump of a mango falling from a bored flying fox's mouth onto the roof.
Remove the flying fox (and there are very few cassowaries available to take over the dispersal role, and then only in the far north), and we'd find the character of our forests changing.
But they eat my lychees and half of my rambutans! They'll put me out of business! What can we do?
I guess, the first thing is to accept that a trade-off has to be made - if one thing the global warming debate, has brought into sharp focus for many who would not have otherwise thought of it, is that "there is no free lunch". ( See "More droughts, more flooding rains"... this issue.) One cannot any longer expect to have pest-free agriculture - we have to expend money and energy to ensure that pest attack is minimised, with minimal side effects to the environment. However, our previous attempts to do this are leading to mounting costs, both for us and for the environment, through use of broad approaches - insecticides being the classical example. (see "Sex sells - pheromones to manage pests" ... this issue.)
We have to become clever. Much cleverer than we have been. We also have to accept the fact that the costs of doing business are rising. Once unthinkable, orchardists are buying expensive grading machines because the Japanese market demands it. Perhaps money expended in ensuring that the fruit is already at its prime when it is picked will bring even more profits. Netting appears to be the most appropriate - having a number of "collateral" advantages. Not only does it reduce flying fox attack, it also reduces bird attack, fruit piercing moth attack, and creates a fairly uniform growing environment. Reports of increased fungal damage in the wet tropics appear to be hearsay. However - while throw-overs may be fine for lychees, they certainly don't work for rambutans - which tend to fruit and leaf through them.
However - it is also evident, that DPI is not going to develop netting systems for farmers, and those mechanically clever farmers are going to have to lead the way with techniques that allow cheap wide area netting, quick and easy furling before windstorms and cyclones, and developing pruning methods that do not entail loss of production (Andre Leu has been pioneering such pruning methods). AND the Rare Fruits Industry is going to have to support them. Don't forget it was Australian Farmers who developed the stumpjump plough and the sugar cane harvester.
Similarly, the development of other techniques of non-lethal deterrent systems needs to be funded (for those farms that cannot be readily netted). At present, nobody in the industry or Government is funding such research, and it is being carried out either by a few committed farmers or poorly funded conservation organisations such as the AUSTROP Foundation.
Techniques such as the Fyre Fox, shooting and poisoning are highly likely to become illegal within the next year, with stringent penalties levied on those caught using them. Not only are they inhumane (only a percentage of animals affected actually die on the site), but they are very effective destroyers of our few remaining flying foxes - and all farmers that I talk to, protest that "they don't want to kill any animals".
Take an opportunity to meet a flying fox - face to face (a LIVE one that is). Visit "Batreach" at Kuranda (on the Jumrum trail behind the Fire Station), visit the Bat House at Cape Tribulation, and the Taiga Bat Hospital in Atherton (they have a bat or two at the Yungabµrra markets). You will be amazed at the real nature of your "enemy" - even sign up to raise a flying fox baby from an injured or tick-paralysed mother.
We can co-exist with the natives - but we are going to have to be prepared to make it easy for them to co-exist with us. We'd hate to have their blood on our heads, yet again.
DATE: November 2000
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