Transcript of Module 32 – Australian Bats

So, I thought, today, we’ll talk about Australian bats.

So, bats are the only mammals capable of sustained flight (1) and are believed to have first flapped their way all the way to Australian shores through Southeast Asia some 23 to 34 million years ago during the Oligocene.

Since their arrival, or perhaps series of arrivals, they’ve diversified (2) into 77 species that now call Australia home. Australian bats have since become an important part of the Australian ecosystem as they act as important pollinators of native plants, they disperse (3) seeds over wide areas, and they also vacuum up (4) insects by the millions on a nightly basis (5).

So, there are two types of bats in Australia. You’ve got your microbats (6) and you’ve got your megabats (7).

As the name suggests, microbats are relatively small. Right? ‘Micro’, ‘microscopic’, ‘microbat’, small bat, and they’ve got a wingspan of up to 25 centimetres and feed primarily on insects such as mosquitoes.

They use echolocation (8) to navigate in complete darkness (9) as well as to track down (10) their unsuspecting prey victims whilst flying at night. That said, they still have eyes and they can still see. So, that expression ‘blind as a bat’ (11), meaning you can’t see, is actually somewhat biologically inaccurate (12).

Some species of microbats spend their days deep within caves, whilst others rest below tree bark or in man-made structures (13) like houses and buildings, before coming out at night to hunt.

The other type of bat is the megabat. Megabats (14), or fruit bats (15) or flying foxes as they’re also known, because of the diet that they eat or the fact that they look like foxes, on the other hand, have a wingspan of up to a metre, right, maybe a little bit less than a full-grown adult, you know, with their arms spread out.

So, unlike their micro cousins, they don’t use echolocation, they don’t have echolocation as an ability, nor do they feed on insects. Instead, they opt for (16) a vegetarian lifestyle eating things like fruit, blossoms, and nectar. Right? Fruit bats.

Due to their lack of echolocation, they have really well-developed eyes and a strong sense of smell, which enables them to locate food in the dark. They live in large social groups in trees called ‘camps’ (17) or ‘colonies’ (18).

Now, are bats dangerous? In and of themselves, bats aren’t really dangerous. You know, you might get scratched or bitten if you were to come into contact with a bat.

However, they do harbour (19) many dangerous parasites and diseases which have proven lethal to (20) humans in the past. Three examples include:

Paralysis ticks (21). One of the 70 or so tick species in Australia, which can inject a potent neurotoxin (22) into its host, whether it be an unfortunate bat, horse, dog, cat, or human. And there have been at least 20 deaths from these ticks in the past. And every year, 500 dogs are killed by them.

Australian Bat Lyssa virus (23) is number two. This is a virus that belongs to the group of viruses that includes rabies, although, we don’t have rabies in Australia. However, Lyssa virus is carried by bats in Australia and anyone working with bats or likely to come into contact with them usually has the vaccination for this virus.

I remember my mum getting three of these vaccinations when I was a kid because she was a biologist working with bats, and it was like a bright pink (24) fluid that they were injecting.

So, the virus can be spread through bites and scratches from bats, and the early symptoms are flu-like symptoms (25), including headaches, fevers, and fatigue. The illness progresses rapidly, leading to paralysis, delirium, convulsions, and death, usually within a week or two.

Although, the vaccine will prevent death if you receive it before or shortly after a bite or scratch from a bat, by the time symptoms arise, it’s usually too late to be cured and you are certain to die, unfortunately, and there have been three human deaths since 1996 in Australia.

The last one is the Hendra virus (26). Now, the Hendra virus is a virus that infects large fruit bats or flying foxes. Sometimes the virus can spread from flying foxes to horses, which can then pass on, in turn, to human beings. Usually, they’re trainers, the trainers of horses, or the vets.

The virus was only discovered following an outbreak in 1994 in a large racing stable in the suburb of Hendra in Brisbane, hence the name.

Symptoms usually arise within the first three weeks after infection, including fever, cough, sore throat, headache, tiredness—all are common initial symptoms—and it leads to meningitis (27) or encephalitis (28) (inflammation of the brain), which can develop causing headaches, high fevers, drowsiness, and sometimes convulsions and coma. And the Hendra virus infection can thus be fatal (29).

Since 1994, 81 horses have died from the infection, and four human beings have lost their lives to it. The most recent occurring in 2009. There is no cure to the virus. You just have to get treatment in hospital until it passes, or it gets the best of you.

So, bat die-offs (30), culls (31), and their danger to humans.

Because of the health risks that bats can pose to humans and pets as well, and the fact that flying foxes tend to live in large numbers and within close proximity (32) to humans, bat culls are often carried out (33) when numbers reach plague proportions (34), when there are way too many bats.

So, hundreds of thousands of bats can be killed by councils around Australia when they become a serious danger or are causing damage to trees in botanical gardens.

When they’re not being killed by humans, they can suffer mass die-offs because of extreme weather events (35) in Australia such as heatwaves. For instance, as mentioned in the video at the start of this episode, in 2018 the heatwave in Sydney killed 100,000 bats in a single weekend.

This is because they can’t sweat. They can’t really regulate their body temperature without flapping their wings or just finding shade. So, if the temperatures rise too much and for too long, bats can die.

So, what should you do if you see a bat? Don’t touch it. Okay? Seriously. Don’t touch bats, unless you’ve been vaccinated. Call your local wildlife hotline (36) if you find one that’s in distress or in need of help. You can usually find those via a quick Google search.

And if for whatever reason you must handle the bat or move the bat, cover the bat with a towel or clothing and make sure you avoid skin contact with the bat. If you’re scratched or bitten or even come into skin-to-skin contact (37) with the bat, see a doctor immediately. Seriously. See a doctor.