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Breaking up bat colonies doesn’t eliminate health risks

The recent tragic death of a young boy from Australian bat lyssavirus (ABL) produced a predictable chorus of calls to disperse flying fox colonies and kill flying foxes, all in the name of public health…

Heavy-handed strategies won’t reduce the risk of bat-borne diseases and will be detrimental to the environment. Flickr/mdavidford

The recent tragic death of a young boy from Australian bat lyssavirus (ABL) produced a predictable chorus of calls to disperse flying fox colonies and kill flying foxes, all in the name of public health. But does persecuting bats actually make us safer?

Protections for bats are being reduced. In Queensland, anyone who wants to disperse a colony has to obtain a Damage Mitigation Permit. Until recently, rules governing these permits covered all protected animals in Queensland. In the latest version of the regulations, flying foxes are given a separate sub-clause which exempts them from the humaneness test that applies to other animals. This is a significant step, making it much more likely permits for dispersing flying foxes will be granted.

The Queensland Premier has suggested he might go further, raising the possibility of employing state government “bat squads” to remove flying fox colonies from urban areas.

Why culling and dispersal don’t work

Dispersing and culling flying foxes cannot eliminate the risk posed by bat lyssavirus. All public health bodies state that there is no inherent public health risk posed by the presence of flying fox colonies. They recommend that members of the public do not touch bats and that they seek medical advice should they have direct contact with one. These two simple measures virtually eliminate the risk of infection with the virus.

Culling can prevent the transmission of a contact-spread virus such as Australian bat lyssavirus, but only if it reduces the density of a bat population to a level where infected animals die before they can pass the disease to another host. Given the low levels of ABL antibody prevalence in flying foxes, the level of culling required to break the transmission cycle within the bat population is phenomenal.

If flying foxes were static occupants of a defined territory, it might be possible to kill enough of them to achieve this goal. But flying foxes live peripatetic lives, moving from colony to colony over impressive distances. Bats killed in urban colonies are simply replaced by others, yielding no net long-term reduction in the size of urban colonies or the pool of animals potentially exposed to lyssavirus.

Attempts to disperse colonies generally fragment them. The fragments become smaller colonies in adjoining suburbs and private spaces, raising, rather than reducing the possible close contact between residents and flying foxes. Colonies re-form and re-occupy roosts, so dispersal is a process which needs to be repeated time and again.

Frank Beveridge, the Mayor of Charters Towers, has had much experience of brute force colony dispersal and concedes that it does not work. His council is now embarking on a far-sighted experiment intended to sustainably move flying foxes into a new publicly acceptable roost site.

Bats and forest biodiversity

Functioning communities of flying foxes provide economic benefits - do we really want to risk those by culling? Flying foxes are the major pollinators of many timber and honey trees. Loss of pollinators has measurable effects on the vitality of forests which provide tangible economic benefits to society.

Flying foxes perform their roles of pollinators and seed dispersers collectively, their effectiveness being tied strongly to presence of a critical mass of animals in the environment. Killing flying foxes at the scale required to influence the occurrence of lyssavirus would disrupt a critical link in forest biodiversity, health and productivity.

Forests do not collapse over night. They slip away, and will, if loss of flying foxes is added to the other challenges they face.

Beyond health risks

Australian bat lyssavirus has now claimed three human lives. It would trivialise the effect of those deaths to get into arguments about the virus in comparison to other causes of death. But it is important to note that, as measured by antibody occurrence in bats and the experience of bat carers, this is a rare virus and the use of heavy-handed reactive methods to solve a complex problem is poor policy.

If culling and dispersing bat colonies cannot be justified on public health grounds, it is hard to avoid the conclusion that the hysterical reaction to having flying fox colonies in urban areas comes more from residents who dislike the noise, smell and occasional damage to vegetation caused by large flying fox camps.

Our political leaders need to do more than just parrot the concerns of their most vocal constituents. The interconnectedness of human health, wildlife and the environment is being increasingly recognised. Simplistic or populist approaches to human-wildlife conflicts can lead to far reaching consequences for no overall benefit.

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49 Comments sorted by

  1. Evol Fayers

    retired

    When another 800 acres of the foxes feeding chain (trees) are destroyed so the sand ridges can be carted away fo make concrete, expect the colony currently existing out here in Cungulla / Cape Cleveland just 25 minutes from Townsville and in throwing distance from the Australian Institute of Marine Science to take up residence in the City. Probably join their displaced relations in the trees at Dan Gleeson Gardens.

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  2. Geoff Henderson

    Graduate

    I am happy to agree that breaking up bat colonies won't (totally) remove health risks. Limiting cars to 10 kph would doubtless fail to stop all road death/injuries too. But it would reduce the incidence of vehicle incidents.

    Moving bats to another location won't remove their ability to transmit disease, but it will lower the chance of the disease being passed on.

    Of course there is more to the issue than health.

    At at times they are a genuine nuisance. Noisy, messy and sometimes quite daunting…

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    1. Maddy Jones

      logged in via Facebook

      In reply to Geoff Henderson

      Geoff,

      - there are 4 species, only 2 are listed as vulnerable (a class of threatened, not endangered) - Greys and Spectacled.
      - species do not have to be rare to be listed, while they are still comparatively common is the best time to work with them as there is still reasonable genetic diversity and it's a lot cheaper than waiting until you are down to your last 43 animals
      - there are a lot fewer of Greys than there were (millions at the turn of last century down to about 350,000 now)
      - the…

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    2. Daryl Dickson
      Daryl Dickson is a Friend of The Conversation.

      logged in via email @wildcardart.com.au

      In reply to Geoff Henderson

      Geoff...you may find it helpful to google CSIRO Flying Foxes... Dr David Westcott...it links you to not only his current work but many articles that may help you understand more about the populations and why they are important.

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    3. Geoff Henderson

      Graduate

      In reply to Maddy Jones

      Maddy thanks to you and others who have taken the time to explain so much to me. Like many I suppose, I had no idea of the complexities of the bat population.

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    4. Joe Gersh

      Executive Chairman at Gersh Investment Partners Limited

      In reply to Geoff Henderson

      Totally agree Geoff. Bats are a nuisance at the best of times, and they create these colonies that are practically impossible to get rid of. They destroy the trees, create a mess than move onto their next location.

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    5. Mike Swinbourne

      logged in via Facebook

      In reply to Joe Gersh

      Totally disagree Joe.

      It's not bats that are the problem - we are. We destroy their habitat, take away their food sources, then complain when they eat our fruit trees.

      Let's just change one word in your post......

      "....Humans are a nuisance at the best of times, and they create these colonies that are practically impossible to get rid of. They destroy the trees, create a mess than move onto their next location...."

      There. That's more accurate.

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    6. Barbara Brindley

      Wildlife Volunteer

      In reply to Geoff Henderson

      So many questions. We have an amazing internet system nowadays where questions can be answered, you can even read up and educate yourself on scientific research about bats and greater knowledge can be gained in ways other than bemoaning conservationists (or tree huggers)! Get to know the answers and discover why we fight for our bats and flying foxes. Did you know there is one species of bat that eats its own body weight every night in mozzies? Thousands of bats flying above eating millions of mozzies…

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    7. Peter Hindrup

      consultant

      In reply to Maddy Jones

      Maddy:
      thank you. So much I didn't know.

      I shared a house for 11 years with micro bats. Fascinating, opinionated, dominating, and all of just under 10 grams in weight.

      Absolutely beautiful.

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    8. Albert Rogers

      logged in via Facebook

      In reply to Geoff Henderson

      Humans in big towns have lost their cuteness too. In many bat species, the endangerment is a result of their low birth rate. I'm not sure if this applies to fruit bats.

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    9. Albert Rogers

      logged in via Facebook

      In reply to Joe Gersh

      "They destroy the trees, create a mess than move onto their next location"
      How very human of them.

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    10. Jane Rawson

      Editor, Energy & Environment at The Conversation

      In reply to Peter Hindrup

      Peter, I'm jealous.

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    11. Peter Hindrup

      consultant

      In reply to Jane Rawson

      And I miss them!
      You haven't lived until you have on the receiving end of a scolding by a barely 10 gram, 4 cm micro bat because it IS dark and I still had the light on kitchen light on!

      Imagination? No chance. happened too often!

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    12. Martin Male

      Somatic Psychotherapist

      In reply to Mike Swinbourne

      Hi Mike I agree with your point. It is time we really reconsidered our impact on the ecosystem not keep "culling the problem". It is humans who consistently create the "problem" with rampant , inconsiderate development and no foresight for the long term consequences of human actions.
      It always seems to be the conservative side of politics (including the right-wing in the Labor party) that raises the fear of nature, removes or reduces the protections fro other species. There have been exceptions like Malcolm Fraser.
      Humans really need to get the reality that we exist within an ecosystem and very action has a effect.

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  3. Mike Jubow

    forestry nurseryman

    I question the following statements, "Flying foxes are the major pollinators of many timber and honey trees. Loss of pollinators has measurable effects on the vitality of forests which provide tangible economic benefits to society.
    Flying foxes perform their roles of pollinators and seed dispersers collectively, their effectiveness being tied strongly to presence of a critical mass of animals in the environment".

    My property is right in flying fox alley and as a forester and biologist, I seriously…

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    1. Greg North

      Retired Engineer

      In reply to Mike Jubow

      Good stuff Mike and just as the James Cook chaps are developing knowledge, it sounds as though something of collaboration between you and them could be of some benefit.

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    2. Barbara Brindley

      Wildlife Volunteer

      In reply to Mike Jubow

      Just a short answer and that is there are certain rainforest trees, plus many natives, ie. eucalyptus, melaleuca trees as well as corymbia, red bloodwood, small gum, swamp bloodwood, quandong, narrow leafed ronbark, Darwin woollybutt, narrow leaved peppermint, forest red gum, weeping paperbark and others that can only be pollinated between the hours of midnight and 3am when birds and bees are not around.

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    3. Daryl Dickson
      Daryl Dickson is a Friend of The Conversation.

      logged in via email @wildcardart.com.au

      In reply to Mike Jubow

      Hi Mike....if you are looking for real data about pollination and flying foxes that is one of the aspects of research that Dr David Westcott & CSIRO have been looking at for the last few years...remarkable and reliable data to support some of the comments being made about long distance pollination of eucalypts...it's interesting stuff and has been quite a surprise to many ...

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  4. Terry Mills

    lawyer retired

    Last year I was scratched by a spectacled flying fox whilst releasing it from bird netting covering a fruit crop. I have no idea where the colony is based and doubt that removing and telocating the colony would stop them ranging widely over areas of fruit production.
    You cannot cull a colony without killing every member and, in my view, that requires us to compromise our humanity.
    I had a course of treatment to protect from lyssavirus with no adverse effects and I understand that I must be more careful in future.
    We have to learn to live with these creatures , innoculate horses in exposed areas and acknowledge that many of our agricultural practices provide an irresisitible and reliable food source for these creatures.

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    1. Greg North

      Retired Engineer

      In reply to Terry Mills

      I suspect you are right Terry about developing techniques to best live with all that nature has bestowed on our planet and I have noted in various locations many hectares of netting over commercial crops, either to thwart birds or it may be the FF.

      I well remember a house builder near where I once lived in Victoria and little did he or I for that matter realise how yummy a community of either Cockatoos or Parrots found cedar and in no time at all the cedar window frames were nearly non existent.

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  5. Jorge Alvear

    logged in via Facebook

    I don't see how culling a whole colony is compromising humanity. Since when are bats more important than people. If animals are not endangered species and present a genuine risk to humans then there is responsibility to preserve humans first before animals. If the cull will not scientifically achieve anything then they shouldn't be culled. Living in Qld for ten years they were an absolute nuisance and made some people's lives hell as some colonies were based in people's backyards but sometimes when the animals welfare are put before the people's welfare then i have an issue with that.

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    1. Mike Swinbourne

      logged in via Facebook

      In reply to Jorge Alvear

      "....I don't see how culling a whole colony is compromising humanity...."

      You may not, but most people accept that killing thousands of animals is not exactly humane.

      "....Since when are bats more important than people...."

      Some species of bats are endangered or threatened - people are not.

      "....If animals are not endangered species and present a genuine risk to humans then there is responsibility to preserve humans first before animals...."

      They don't present a genuine risk to humans…

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    2. Hugh McColl

      Geographer

      In reply to Mike Swinbourne

      It's a very good point that 'domestic' dogs kill more Australians than fruit bats do. Dogs probably also shit in many more inappropriate public places, take up far more food aisles in our supermarkets and account for so many more hassles of local government. Surely the miniscule problems brought about by bats do not require nationwide eradication campaigns hyped up by attention-seeking politicians and their gun loving sidekicks in suburbia?

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    3. Dianna Arthur
      Dianna Arthur is a Friend of The Conversation.

      Environmentalist

      In reply to Mike Swinbourne

      I recall arguing with a Queenslander complaining the increase in crocodiles were ruining his weekend getaways, I suggested he stay out of their territory.

      Culls remain the easy, temporary option and solve nothing - if anything they further erode our precarious ecosystems. Learning to live with our environment instead of battling with it isn't easy, but we cannot deny any longer that the most invasive, destructive and over populated species on Earth is us.

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    4. Mike Jubow

      forestry nurseryman

      In reply to Dianna Arthur

      G'day Dianna,
      We have crocs active in our creek, particularly when it is in full flow during the wet season. I don't particularly care for them but we live with them and leave them alone. I have often thought that for those that are into extreme sports, there is an opportunity for boosting tourism with a new sport. There is a set of rapids in the creek just near our house and I reckoned if we put a saddle and bridle on a croc, it would make for an exhilarating ride down the rapids. Surely the people who climb cliffs without a harness, bungee jumpers, sky divers and their ilk would be willing to have a go. Should make a motza with this idea.

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    5. Mike Jubow

      forestry nurseryman

      In reply to Mike Swinbourne

      "- and shit everywhere (buy a broom)". If you had a dozen dogs or even people come and crap in your yard every day, you would certainly be entitled to complain to the authorities that it is a health hazard. So why is it suddenly OK to have a thousand flying foxes doing the same thing? Don't flying foxes have pathogenic bacteria in their enteric system like E.coli? A broom is no help in cleaning up bat turds. Not only that, bat shit on the paintwork of your house and car, once dried, is hard to remove and can strip the paint down to the base. Are all the bat protectors going to chip in and buy the affected residents clothes driers and pay for an annual repaint of the house? You can't hang washing on the line in these circumstances. To deny bat droppings is a health hazard just doesn't make sense to me. That would be my main argument in having them moved out of residential areas.

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    6. Dianna Arthur
      Dianna Arthur is a Friend of The Conversation.

      Environmentalist

      In reply to Mike Jubow

      Heh, heh.

      Think I'll suggest that to my "humans-are superior" antagonist.

      Very entrepreneurial of you, plus enhancing evolution of both crocs and humans. What could possibly be wrong with that?

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    7. Dianna Arthur
      Dianna Arthur is a Friend of The Conversation.

      Environmentalist

      In reply to Mike Jubow

      Or plan residential areas away from bushland. We can build in areas we have already screwed up by mining or fracking.

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    8. Barbara Brindley

      Wildlife Volunteer

      In reply to Jorge Alvear

      It has been proven that dispersing bats or culling bats does not work. Bats are most definitely more important than people. They've been doing their vital work on our planet for 50 million years for a start, and they DO NOT pass the Hendra disease to horses. They carry both the Hendra-virus and the Lyssavirus but there has never been one confirmed case of a bat passing Hendra to a horse. Check out Dr Les Hall, and/or The Australian Veterinary website! They cannot confirm it, it is all assumption…

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    9. Barbara Brindley

      Wildlife Volunteer

      In reply to Mike Jubow

      Bird shit is more difficult to remove from cars and less erosive than bat shit. Ecoli is found in kangaroo meat, not in bats. We live in Australia where there are poisonous creatures ie. wildlife, and people realise this, or mostly they do, but over a 30 year period 70 people have died from box jellyfish, 50 from crocodile attacks, 41 from snake attacks, 14 from poisonous spiders, 3 from the stingray and stone fish. ONLY 2 people have died from the Lyssavirus in the same period (confirmed cases…

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    10. Mike Swinbourne

      logged in via Facebook

      In reply to Mike Jubow

      "....Don't flying foxes have pathogenic bacteria in their enteric system like E.coli?..."

      Almost all mammals have E. coli in their gut - we do as well.

      "....A broom is no help in cleaning up bat turds...."

      Then buy a shovel instead.

      ".... bat shit on the paintwork of your house and car, once dried, is hard to remove and can strip the paint down to the base...."

      Then remove it before it dries, repaint if necessary, or keep your car under cover.

      ".... Are all the bat protectors going…

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    11. Mike Jubow

      forestry nurseryman

      In reply to Barbara Brindley

      So, I can take it from the tone of your response that you would have no problem living amongst a flying fox camp? No E. coli in a flying foxes gut? Amazing! Presumably, there no other pathogens in their gut either. And 100 or so trees that only a bat can pollinate? Please name them or give us a reliable reference. " Bird shit is more difficult to remove from cars and less erosive than bat shit." It is unlikely that you have had to clean up bat shit off a house. A high pressure cleaner is needed before…

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    12. Mike Jubow

      forestry nurseryman

      In reply to Mike Swinbourne

      "But then, my advice to you is not to eat bat shit".
      What a stupid and asinine reply.

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    13. Mike Swinbourne

      logged in via Facebook

      In reply to Mike Jubow

      Stupid AND asinine? You do know that's a tautology, right?

      But seriously Mike, in what way is the supposed E coli. in bat shit from your backyard a health hazard if you do not ingest it?

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    14. Barbara Brindley

      Wildlife Volunteer

      In reply to Mike Jubow

      I've had to clean bat shit and bird shit off my car, but I haven't left it to require more than a wet sponge. I would have no problem living amongst a flying fox camp, I rescue them daily and care for them until release stage, I have spent months living amongst them in a caring capacity, as many as 140+ that were recently released. I've touched their urine, poo, been scratched by them, and bitten by them, but I'm vaccinated, which people who are scared can also do if they wish, but as there is a…

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    15. Barbara Brindley

      Wildlife Volunteer

      In reply to Mike Jubow

      I agree with Mike though...."Alternatively, you could learn to accept that you are lucky enough to have a beautiful native animal frequenting your area. Some people live in the centre of cities with no appreciable natural environment around them. If you don't like nature, you could join them." You can’t pick and choose the wildlife in your area, just because you particularly like one and not another. Bats are here forever…. Bats rule.
      Many people have learned to co-exist with bats, it's a losing…

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    16. Mike Jubow

      forestry nurseryman

      In reply to Mike Swinbourne

      If you can't work that out try thinking about inhalation of batshitdust and skin irritation and absorption. Or are you thick as well? The people of North Eaton had terrible health problems while a bat colony was allowed to stay in their little village for five years before they were finally dispersed.
      Would you choose to live in those conditions?
      Being deliberately obtuse doesn't convince anyone of your point of view.

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    17. Mike Jubow

      forestry nurseryman

      In reply to Barbara Brindley

      Big deal, you have lived amongst 140+ bats, which are in confinement, as a wildlife carer. You have not lived amongst thousands of them as you would find in a bat camp. Nor have you had thousands of them pooping all over your roof and yard every day for five years. Really, I don't think you know what it is like.

      Now as to pollination, show me a properly researched paper that verifies your claims. We have bats where I live and I am aware of when they visit the trees in our area. It is seasonal…

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    18. Mike Swinbourne

      logged in via Facebook

      In reply to Mike Jubow

      "....Being deliberately obtuse doesn't convince anyone of your point of view...."

      Neither does being abusive - but if that's the best you can do, go for it!

      Nor does putting forward examples without supporting evidence. How about you describe these 'health problems' that the people of North Eton suffered from. And no - disliking the smell or the noise is not a health problem.

      I can provide you with a link to the Queensland Government report if you are struggling.

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    19. Barbara Brindley

      Wildlife Volunteer

      In reply to Mike Swinbourne

      When we acknowledge that bats have been on the planet 50 million years, before human interference, we can also acknowledge that we are living in their space, forcing them out of their "natural" environment as they go about innocently doing the vital work they were predestined to do. Thankfully there are many bats to cope with the negative anti-bat multitude of people wanting them dispersed, culled or whatever.. I rescue bats mostly from barbed-wire, not so many from fruit tree netting because they…

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    20. Barb Brindley

      logged in via Facebook

      In reply to Mike Jubow

      Someone getting a bit upset .... education is lacking again. Bats are pollinating purely by being close to the flower, it catches on their wings and fur and when they fly 50 kms they scatter the pollen, ie. cross pollinating. They eat and chew because of their very fast digestive system, it's how it works. Peer reviewed research is everywhere if you can be bothered to educate yourself. I can't imagine for one minute that you'd consider ringing and speaking to someone calmly to learn/educate yourself…

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    21. Albert Rogers

      logged in via Facebook

      In reply to Mike Jubow

      Besides which, E.coli is a very variable bacterium. It is a marker for the presence of faeces in water that shouldn't have any, so it is equated with disease, but mammal and bird bodies are evidently well able to tolerate most strains, or they'd all have high rates of sickness.

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  6. Lindsay Davis

    logged in via email @hotmail.com

    Interesting article, in particular the third paragraph where the author states "Bats killed in urban colonies are simply replaced by others, yielding no net long-term reduction". I can't help wondering why our authorities in the Northern Territory don't understand this in regard to crocodiles. They trap crocodiles in Darwin harbour in increasing numbers. Yet they haven't connected this to increase in numbers and animal size in the flood plans.

    It is there that the reduction needs to take place by culling (shooting) by either government employees or allowing the public to do so. They presenting allow Magpie Geese hunting and they harm no one. This would be a wise extension.

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  7. Albert Rogers

    logged in via Facebook

    In "The Screwtape Letters", in the preface C.S.Lewis notes that angels are depicted with bird wings, devils with those of bats. He then says that he likes bats better than bureaucrats, and depicts Hell as a bureaucracy. Note that bureaucracies are as common in the pivate sector as in the public, and in many cases even more intransigent.

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  8. Brad Law

    Wildlife Ecologist

    Mike – you are right that there has not a huge amount of research on flying fox pollination, however, what has been done suggests flying foxes are likely to be very important pollinators. This is because they carry huge pollen loads on their fur and wings and transport pollen over large distances. One shouldn’t get too carried away though, because most Australian trees have a raft of pollinators, including honeyeaters, lorikeets, marsupial gliders and insects as well as flying foxes. But it is quite…

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  9. Pamela H.

    logged in via email @hotmail.com

    An easy way to prevent the risk of being bitten; leave them alone.

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    1. Paul Prociv

      ex medical academic; botanical engineer

      In reply to Pamela H.

      Over 5 years in the early 1980s, while investigating an unexplained disease outbreak in a human population, I personally caught and/or handled many flying foxes (FFs), and dissected about 1,000 of them, without using any protective clothing (not even gloves), but did not pick up any infections. While finding the epidemic to be unrelated to FF parasites, I also discovered just how little we knew about them, and what smart, affectionate and likeable creatures they can be. Maybe they’ve now become…

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