Maverick Life

Maverick Life

Angels of the night – it’s time to cut bats some slack

Bats. Computer artwork of three bats flying.

In Western mythology, spooky, nocturnal creatures like bats never stood a chance. In China they were once revered, but right now they’re in big trouble and stand convicted for laying us low. They need help, so I hereby appoint myself counsel for their defence.

Look, I know, this isn’t going to be an easy sell. Half the world is in lockdown because a pangolin slurped up some batshit and gave the world Covid-19. As a result, we’re now all cowering in houses, huts and apartments wondering when the hell it will end.

But it’s our fault, not theirs. If we think a solution to coronaviruses is to eliminate bats, it would spark an unmitigated ecological disaster. So I plead their case.

This is not the first time humans have been pissed off with bats. The problem began way back with angels. If God was in heaven and humans were on earth – some monkish Biblical illustrator must have reasoned – then the only way to commute between the two must be to fly. And the only flight he could imagine was the type birds did.

So angels were drawn with light-filled frocks and white avian wings. Sometime later, pink cherubs with deftly concealed privates appeared, doing service around lovers.

However, the trouble came with Lucifer, God’s fallen angel. He had to have wings too, being an angel, but not the nice feathery kind. One can imagine the scribe — probably a sixth-century Benedictine monk — scratching his bald pate and conjuring up an appropriate form for Beelzebub: a black, silent, night-shrouded, leather-winged, goat-horned embodiment of evil. It was to be very bad news for bats.

I was reflecting on this in the forest’s inky darkness because it seemed preferable to the thought of being snapped in half by an enraged hippo which might soon run into our mist net.

There were two other nets out across nearby game paths on Lake St Lucia’s Nibela Peninsula – and hippos are nocturnal grazers. Merlin Tuttle, the head of Bat Conservation International, had his finger on the hair-thin net to monitor bat contact and hippos didn’t seem to worry him.

“Just dive through a gap that a hippo can’t fit through,” he advised. “They’re fat and you’re not.”

A slight jiggle of the net signalled the capture of what turned out to be an extremely irritated Egyptian fruit bat. Merlin disentangled it deftly as I made my way round the net to have a look.

What happened as I peered at the creature in his hand can best be described as an instant collapse of stereotypes: the bat was absolutely beautiful. It looked rather like a tiny, flying Jack Russell, but with delicate radar ears, a long brown snout, puppy nostrils and the most intelligent eyes imaginable.

Merlin lowered it into a soft cloth bag to photograph later and I picked my way to another net, trying to remember what a hippo on the trot sounded like.

Merlin, based in Austin, Texas, is a population biologist turned bat friend. “Do you know that nearly a quarter of all mammal species can fly?” he asked moments after we’d met. “There are nearly a thousand species of bat: it’s the most prolific mammalian order. Think about that.”

I did. And if you ever thought bats were yucky, disease-bearing bloodsuckers hard-wired to tangle in your hair and infect us with viruses, Merlin’s the man to dispel your cherished myths. It will take him a few minutes to have you doing penance for previous attitudes towards the order Chiroptera (that’s bats).

Going bats in China

In Chinese culture bats are still, I hope, symbols of good luck, while in some countries they’re simply a good meal. An Australian cookbook recommends flying-fox stew in spite of the “strong and unpleasant smell which departs with the removal of the skin and wings”. Cooked with onions and herbs and boiled for a couple of hours, “you would hardly know the flesh from pork”.

But apart from obviously half-starved outback types, European peoples have, for thousands of years, associated bats with graveyards, witches, the underworld and the Devil himself. For the brewing of some venal evil, Shakespeare had his witches in Macbeth stir in “eye of a newt and toe of frog, wool of bat and tongue of dog”.

The real wool of bat, however, is the guff which seems to have stuck to these little mammals over the years.

Bats aren’t blind – they wouldn’t be so stupid as to tangle in your hair. Also, there are only three species of vampire bats and they’re all in South America. Bats are about as evil as Labradors, they’ve never been known to attack humans – they’re far less likely to carry rabies than your Pekingese.

However …

Bats do carry zoonic viruses – around 60 at last count – that cause problems for humans. These include Hendra, Marburg, Covid-19 and possibly Ebola and Nipah. That we contract these diseases is entirely due to how we treat wildlife.

When humans started creeping into areas where bats live, especially in the tropics, it led to an increased risk of contact. In Malaysia, for instance, commercial pig farms were installed in bat-inhabited forests, which consequently led to the first human outbreak of Nipah via pigs. As we continue to move into jungles on the planet, we will see more and more outbreaks of zoonotic viruses.

So why don’t bats get sick? There are a few theories. One is that flight raises their temperature to over 40 degrees Celsius, which neutralises any virus. Another, by Peng Zhou and colleagues at the Wuhan Institute of Virology in China, is that their immune system can rapidly mount a robust antiviral response whenever a pathogen is detected by releasing anti-inflammatory cytokines. Bats have been around for 50 million years to perfect this; humans only around three million. Our bodies have yet to learn that trick.

Bat tricks

What bats do is far more interesting. Take the baobab. At a certain time of year, around sunset, baobabs will curl the white petals of their flowers upwards. Before long, straw-coloured or epauletted fruit bats will flutter in and sup delicately from the underside of the petals – clasping, all the while, the pollen-coated reproductive organs which hang as a convenient perch.

After an evening of boozing it up on nectar, the bats will be satiated and the baobabs will be pollinated. Without these pollinators, the baobab would die out, triggering a chain of linked extinctions of many other plants and animals.

Indeed, it has been estimated that up to 90% of Africa’s tropical forest trees and many savanna trees are pollinated by fruit bats. These include the many fig species, wild plums, water berries, wild pears, Cape ash, bitter almonds, cotton trees and sausage trees. They also do service for peaches, bananas, avocados, plantain, mangos, guavas, breadfruit and dates. Really evil little things, bats!

They are also vital forest re-seeders. Take wild figs. A single bat can take in and pass out around 60,000 seeds a night. Over a period of several nights bats may process nearly a ton of fruit from a single fig tree.

Because flying with a tum full of fig consumes energy, bats let go between trees and in clearings (of course this is where termites build mounds which attract pangolins).

Seeding clearings is, of course, the most efficient way imaginable to re-seed cut-back forest areas. Birds, on the other hand, generally sit first before they poop, so their planting is done in much-contested soil below existing trees.

If only 1% of the seeds dispersed by an average-sized tropical bat roost grew, it would mean something like 100,000 new trees a year. Anyone interested in rainforest preservation should be praying to the god of bats to keep them safe, warm and well fed.

A bat snack

Not that it would interest them, but these busy little forest gardeners are causing a bit of a scientific storm among more recent mammals. Fruit bats are classed as megabats and their insect-eating lookalikes are microbats. For scientific reasons too complex to go into, some hypothesise that megabats evolved from primates, while microbats evolved from a shrew-like, tree-living creature. They’re about as related to each other as a tiger to a sea otter.

When Merlin hauled the fruit bat out of its bag it looked, on reflection, more like a lemur than a Jack Russel. He held it gently to prevent it struggling too much and, with a syringe, placed a droplet of apricot baby food on its tiny snout. It slurped it up with a long red tongue and smacked its lips.

After establishing that we were friendly and the apricot mush was in good supply, it settled back in his hand like a puppy on a pillow. It clearly knew how to train humans. I could swear I heard a little sigh of contentment. An Angolan free-tailed bat in the other bag was rather harder to please and frowned at Merlin comically until he produced a mealworm.

Bad eyes, good ears, better radar

The family name for free-tailed bats is Molossidae, which comes from the Greek word molossus, a type of pug-nosed dog used by Greek shepherds in ancient times. Their strange little faces and large ears are part of the remarkable echolocation equipment which microbats use to detect their prey.

The battle between insects and bats has developed some of the world’s finest bio-weaponry. Millions of years ago, before the appearance of bats, the night was safe for insects, many of which developed a nocturnal lifestyle. By using high-pitched clicks and buzzes, microbats developed a system of radar which, today, is millions of times more efficient than anything humans have yet produced.

Some insects were forced to move back to daylight activity, while others developed defence systems. One was the bat ear, found in certain moths, lacewings, praying mantises and perhaps some beetles. They can detect bat clicks and take avoiding action, either veering off, flying in wild loops or, if the bat has locked on to them with its ‘feeding buzz’, folding their wings and dropping to the ground.

Certain tiger moths go one better. At the final moment of the bat’s attack, the moth blasts back streams of high-pitched clicks. It’s rather like saying ‘Boo!’ to the bat, and very often confuses it enough to save the moth. Some bats, with stealth-bomber tactics, have retaliated by pitching their buzz at such a high frequency the moths can’t hear it.

Fish-eating bats have tuned their echolocation to such a high degree that they can pinpoint a single human hair on the surface of a pond. They detect minnows swimming below the water surface, spearing them with a specially developed claw.

Frog-eating bats know their favourite frogs by the songs they sing and lock onto the sound unerringly. Juicy, fat croakers never stand a chance.

A good ear also helps with mothering. Bracken Cave in Texas houses between 20 and 40 million bats – the largest concentration of mammals in the world. Some 270 tonnes of bats roost in densities of about 5,000 a square metre. When the mothers go hunting, they leave their babies hooked to the roof among millions of peers, locating them later by their squeaks.

The real value of microbats though is the sheer volume of insects they eat: without them we’d simply be overrun. One colony of 20 million free-tailed bats can eat more than 100,000 kilograms of insects a night. That’s the equivalent weight of around 20 elephants.

Many bats include mosquitoes in their diet: little brown bats, for example, can catch up to 1,200 mosquito-sized insects a night. On reflection, there may be a direct relationship with the increase in malaria and the decline of bat populations throughout Africa. More bats mean more forests, more fruit and fewer pests.

The really bad news is that bats are among the most vulnerable to extinction of any animal on earth. Some females produce only one baby each year. Others require up to five years to leave just two surviving offspring. In Europe, many bat populations are estimated to have declined by 90% or more in the past 20 years and are now endangered. A crash in bat populations could give us a foretaste of the hell so many people fear that bats represent.

Up, up and away

After our captured bats had been fed and photographed, they looked rather contented. But they had things to do and places to go, so Merlin carried them to the veranda. I shone a beam into the dark night and the bats lifted from his hands. The light set their fur aglow and they seemed to dance into the sky. It was the nearest thing I’d ever seen to a flight of angels. DM/ML

For more on bats, look at this cartoon by First Dog on the Moon published on The Guardian.