by Adam Frost
‘Maybe,’ said Terry, ‘but for me the most amazing thing about bats is echolocation. And those bats in there can’t echolocate. Hardly any megabats can.’
‘I’ve read about that,’ Sophie said. ‘It’s something to do with finding your way around using squeaks.’
Terry nodded. ‘As you know, bats are nocturnal, which means they can’t rely on sunlight to help them see. Now, if you’re a fruit bat –’ he nodded at the bats in the enclosure – ‘you’ll mainly use your sense of smell to work out where you are. But microbats, like the ones we saw in the Nightzone, are different. They rely on hearing. When they’re flying, they make a high-pitched squeaking noise. This noise will bounce off anything in the surrounding area. Maybe a tree trunk. Maybe a moth. The bats’ large ears hear the noise bouncing back. From the speed and volume of the echo, they work out where the object is.’
‘That’s amazing!’ said Tom.
‘I know,’ said Terry, ‘but that’s not all. Then they squeak again. The noise rebounds again. Now they have two pieces of information. They can work out whether the object is big or small, whether it’s moving or standing still. They squeak again and get another update. As they get closer and closer to the object, they squeak more and more, continually getting more data. Then finally they catch the moth or dodge the tree or land in the cave.’
‘That’s incredible!’ said Sophie.
‘Exactly,’ said Terry. ‘Pretty amazing. And think about what they’re actually doing. They’re putting together a 3D map of the world around them. Using nothing but sound waves. And changing it every millisecond. While they’re moving.’
Tom and Sophie let this information sink in.
‘Looks like we’ve got a new favourite animal,’ Sophie said.
Tom nodded. ‘Now I understand why Batman wanted to dress up as a bat. Spiderman and Catwoman got it all wrong.’
At that moment, Polly the bat sprang off her perch, fluttered across the enclosure and landed on the feeding station. Terry smiled. ‘She’s OK. All is well,’ he said.
He walked towards the exit, with Tom and Sophie following him. As he opened the door to leave, Mrs Nightingale stepped in through it.
‘Ah, Terry, glad you’re here,’ she said. ‘We need your help at the hospital.’
She peered over Terry’s shoulder.
‘Hello, you two,’ she said. ‘What’s your favourite nocturnal animal so far?’
‘Well, generally speaking, bats,’ said Sophie.
‘But we can’t decide between these fruit bats and the Seba’s Short-tailed Bats,’ said Tom. ‘There are so many differences between microbats and megabats and some of them –’
‘OK, OK, I get it,’ said Mrs Nightingale. ‘You like bats. You can tell me more later. Right now, I need to borrow Terry.’
Terry smiled. ‘See you soon, you two. Maybe next weekend?’
‘Tomorrow,’ Tom and Sophie said in unison.
‘Same time, same place,’ Sophie added.
Chapter 5
That evening, Tom and Sophie walked back to The Ark with their parents. They were talking mostly about bats, but also discussing scorpions, naked mole rats, pottos, lorises and armadillos.
‘Can we go out on the canal bank tonight?’ Sophie asked her mum.
‘Yeah, we want to try to spot more nocturnal animals,’ said Tom.
‘OK, but you stay inside the marina,’ said Mrs Nightingale.
‘If you want to do any bat-spotting further along the canal, you come and get one of us,’ said Mr Nightingale.
‘What do you mean, “bat-spotting”?’ Sophie asked.
‘Well, I thought you said you were going out looking for nocturnal animals?’ Mr Nightingale said.
‘Yeah, but we were thinking foxes, badgers and mice,’ said Sophie.
‘We didn’t realise there were any bats on our part of the canal,’ said Tom.
‘Now you’ve done it,’ sighed Mrs Nightingale.
‘So there are real bats – actually living here near our boat?’ Sophie asked.
‘Loads,’ said Mr Nightingale. ‘Daubenton’s and Common Pipistrelles mainly. But maybe others. They feed on the midges you see hovering above the water, and live in the trees nearby.’
‘Great, we can use the night-vision goggles to watch them in action,’ said Tom.
‘Sorry, Tom,’ said Mr Nightingale, ‘those goggles actually belonged to the zoo and I had to give them back. Tell you what, if you really want to see some bats, ask your grandad. He’s photographed loads of nocturnal animals in his time. He knows all kinds of tricks.’
Tom and Sophie wolfed down their dinner. As they ate, Sophie flicked through The Junior Bat Spotter’s Guide and Tom skim-read The Big Book of British Bats.
They glugged down their water, piled into their coats and ran along the towpath to Grandad’s boat.
Grandad listened to them carefully as they rattled through their plan for the evening.
‘Excellent idea,’ he said. ‘Now, there are all kinds of ways of spotting animals at night, but the best thing is to use a specially adapted torch. Come with me.’
He walked along the narrow corridor that ran the length of his houseboat, stopping at a small cupboard door. Then he opened it and beckoned Tom and Sophie to follow him inside.
‘What’s this, Grandad?’ Tom asked. ‘A secret portal to another world?’
‘Something like that,’ Grandad replied.
They found themselves in a small dark room with no windows, and a shelf of strange-looking liquids in plastic bottles. There was a sink in one corner and two washing lines attached to the ceiling. The washing lines had photographs of animals hanging from them.
‘This is my darkroom,’ Grandad said. I use it to develop my own photos. I use the chemicals you can see in those bottles.’
‘I knew you liked taking photos, but this is crazy,’ said Tom.
‘So why does it need to be dark, Grandad?’ Sophie asked.
‘Because when you develop photos taken on an old-fashioned camera, it must be totally pitch black,’ said Grandad. ‘Any light spoils the film and makes the whole photo completely white. Which is why . . .’
Grandad closed the door.
The room was totally dark. There wasn’t a hint of light from anywhere.
‘Wow,’ whispered Sophie.
Tom held his hand in front of his face but couldn’t even see the outline.
Then a small lamp came on in the corner of the room. It gave off a faint red glow.
‘This is my safe light,’ said Grandad. ‘It has a special red filter over it. It means I can see what I’m doing, but it stops the light from damaging the film.’
He opened a drawer and took out two torches.
‘These torches have the same kind of filter on them. They’ll help you to see in the dark.’
He handed one torch to Tom and the other to Sophie.
‘But why don’t we just use normal torches?’ Tom asked.
‘Because bats are a bit like the film in my camera,’ said Grandad. ‘They don’t like bright light. If you use normal torches, they’ll be frightened away.’
‘Cool,’ said Tom, flicking his torch on and off.
‘Are you coming with us, Grandad?’ Sophie asked.
‘No, no,’ said Grandad, shaking his head. ‘Bat-watching is a young man’s game. Or a young lady’s, of course. But stop by on your way back – I want to hear all about it.’
‘OK, Grandad,’ said Tom, heading towards the door.
‘Thanks,’ said Sophie, following Tom out.
As they ran along the canal, Tom and Sophie chatted about their grandad’s darkroom.
‘Do you think Mum and Dad would get one of those in our houseboat?’ Tom asked.
‘What for?’ Sophie replied. ‘None of us are really into photography.’
‘No, I mean for us,’ Tom said. ‘We love nocturnal animals, right? And we’re going to be spending a lot of time looking for them, right? So we need to get us
ed to the dark.’
Sophie shrugged. ‘Maybe. But I think just being out on the canal is the best training. I can already feel my eyes adjusting.’
Tom said, ‘Me too. I can basically see everything.’
He nearly tripped over a paving stone, but quickly recovered his footing as if it hadn’t happened.
They had reached a quiet section of the towpath, just on the edge of the marina. They crouched down and shone their torches on to the water and up into the trees behind them.
‘If Mum and Dad let me,’ Tom whispered, ‘I’d like to become properly nocturnal. You know – sleep during the day.’
‘Tom,’ Sophie said, ‘they’re not going to let you. What about school?’
‘Didn’t Dad go to night school?’ Tom said. ‘I’ll just do that instead.’
‘Yeah, I suppose,’ Sophie said.
A few seconds later, they heard distant fluttering and squeaking. They shone their torches towards the sound.
‘I can’t believe there are bats right here and we didn’t even know about it,’ Tom said quietly.
‘I know,’ Sophie replied. ‘We spend so much time in the zoo that we forget about all the animals that live right here.’
‘Where are they though?’ Tom said. ‘I can’t pick them out.’
They both shone their torches on to the water and then up into the trees behind them, but they couldn’t see any bats.
There was another series of squeaks.
‘Over there by the bridge,’ said Sophie.
They could see dark black shapes swooping through the air about fifty metres ahead of them. It wasn’t pitch black yet, so the bats were still visible against the deep blue of the evening sky.
‘They look like birds from here,’ said Tom.
‘Let’s get closer,’ said Sophie.
They walked further along the towpath, keeping the red light of their torches trained on the cloud of bats.
‘They must be feeding on the midges that gather under the bridge,’ said Sophie.
‘Look at that one,’ whispered Tom.
He pointed at a bat that was heading in their direction. It was darting up and down, and then hovering in mid-air.
‘It must be hunting a moth,’ said Sophie.
‘So why can’t it just catch the moth and eat it?’ Tom asked.
‘According to that book I was reading, some moths have evolved a defence mechanism,’ said Sophie. ‘They emit a high-pitched sound that confuses bats. Messes with their echolocation.’
‘So what happens?’ Tom asked.
‘Let’s watch. Maybe we’ll find out,’ Sophie said.
The bat was still hovering in mid-air. Tom and Sophie trained their torches on the bat and saw a moth fluttering just in front of it. The bat jerked upward, the moth flapped backwards, the bat darted forward, the moth fluttered sideways, the bat flew in a clockwise circle, the moth flew in an anticlockwise circle. All of this happened in a split second.
‘Wow,’ whispered Tom.
The bat suddenly jutted its legs out and swooped forward.
‘He caught it,’ said Sophie.
The bat darted off, crunching the moth in his jaws.
‘So the bat won that one,’ Tom said. ‘Whoa, look at those ones over there.’ He swept his torch back across to the group of bats by the bridge.
‘It’s like they’re dive-bombing,’ he said.
Two or three of the bats were flying above the water, getting lower and lower, until finally they skimmed the surface of the canal and took off again.
‘I bet they’re catching all those insects that hover just above the water,’ said Sophie.
‘But how come the bats never land in the canal?’
‘Maybe their squeaks bounce off the water,’ said Sophie, ‘so they know when to take off again.’
They shone their torches on a bat that was starting to swoop down towards the water, following it with their beams.
As it skimmed across the surface of the canal, it seemed to catch one insect with its wing and pass it into its mouth, crunching it up with its jaws. But, at the same time, a larger insect disappeared into the bat’s tail.
‘Did you see that?’ Sophie asked.
Tom nodded, puzzled.
Another bat swooped down from the bridge. It caught a midge with its claws and passed it into its mouth. But a second insect seemed to be scooped up by the bat’s tail.
‘What do you think it’s doing?’ Tom asked.
‘Keeping some food for later?’ Sophie suggested. ‘But I can’t see how.’
‘Let’s ask Grandad about it when we get back,’ Tom said.
‘What are you asking Grandad?’ said a voice behind them.
They turned around and saw their grandad standing behind them.
‘I’ve come to round you both up,’ he said. ‘It’s half past eight already.’
‘It can’t be,’ said Sophie. ‘We got here at seven.’
‘You’ve been watching bats for an hour and a half,’ said Grandad.
‘We can’t have been,’ said Tom. ‘That’s impossible.’
‘Time flies when you’re watching bats,’ said Grandad with a smile. ‘You end up getting drawn into their world. They’re great hunters.’
Tom asked Grandad about the bats that had skimmed across the surface of the canal, catching some insects with their wings and seeming to scoop up others with their tails.
‘They’ll be Daubenton’s,’ said Grandad, ‘very clever bats. They have a pouch under their tails. They can use it to sweep up prey. Also to store anything they catch.’
‘So what you’re saying is,’ Tom said, ‘they catch moths with their bottoms.’
‘That’s it,’ said Grandad with a smile.
He led them back along the towpath towards The Ark.
‘The bats we saw looked like adults,’ said Sophie. ‘Are there no baby bats around at the moment?’
‘Well, they won’t be flying anywhere yet,’ said Grandad, ‘but yes, springtime is usually when bats start having their kits. They wake up from hibernation, the females find a maternity roost and then start having babies shortly afterwards.’
‘That’s pretty quick, isn’t it?’ Sophie said.
‘Well, one other thing that some bats do is mate before they hibernate,’ said Grandad, ‘so it’s all out of the way. Then they delay getting pregnant while they’re hibernating. Everything in their body completely stops. When they wake up, things kick off again and the baby bat starts growing inside its mother.’
‘That’s amazing,’ said Sophie.
‘So as well as flying, and echolocating, and sleeping upside down, they can decide when to have a baby,’ said Tom.
Grandad nodded. ‘It must be splendid being a bat!’
Chapter 6
All that week at school, neither Tom nor Sophie could concentrate. Tom spent hours drawing pictures of different kinds of bats in the back of his maths book. Sophie nearly got caught secretly reading her Junior Bat Spotter’s Guide under the table in a history lesson.
Each evening, they couldn’t wait for it to get dark so they could go back to the towpath and pick out bats with their torches, whispering about what they could see. By Friday, they had become experts at spotting bats, even at long distances.
‘Look at that one!’ exclaimed Sophie.
She trained the beam of her torch on a bat that was flapping away from the canal.
‘Can you see it?’ Sophie said. ‘On its back?’
Tom nodded. It was a baby bat, clinging on to its mother’s back with its tiny claws.
They watched the mother and baby as they flew off over the trees.
‘There’s another one,’ said Sophie. ‘Look.’
Another bat with a small black shape on its back sped across the sky. Then another.
‘What do you think they’re doing?’ Tom asked.
‘I don’t know,’ said Sophie. ‘I read in my book that sometimes bats move house. They all decide to leave one r
oost and find another one. Maybe that’s what they’re doing.’
Within seconds, the sky above their head was full of squeaking, flapping, fluttering bats. Tom and Sophie shone their torches straight up and stared.
Soon it was quieter again. A few bats were still hovering under the bridge, but there was no sign of the others.
‘Will they come back?’ Tom asked.
‘I don’t know,’ said Sophie.
‘Do you think there are bats in other parts of the marina?’ asked Tom.
‘Let’s find out,’ said Sophie.
They turned to leave.
‘I know they’ve gone,’ Tom said. ‘but it’s like I can still hear one of them squeaking.’
‘Yeah, I know what you mean,’ Sophie said, ‘but it’s not coming from the sky.’
‘So where is it coming from?’ Tom asked.
They both listened as hard as they could.
‘Let’s close our eyes,’ said Tom. ‘It works for bats.’
They both closed their eyes tight and concentrated on the sounds. The night air was cold on their faces.
They picked out the water lapping the bank in front of them, the trees rustling behind them, the barges creaking further up the canal, the quiet murmur of cars on the street beyond.
‘Wow,’ said Sophie, her eyes still scrunched up. ‘It does actually help.’
‘There it is!’ exclaimed Tom, holding up his finger. He kept his eyes closed and took a step towards the sound. He stopped and listened again. He took another step.
Seconds later, they were crouching down, looking at a small brown creature squirming in a patch of grass. It was stabbing the ground with its wings, trying to propel itself forward.
‘It’s a baby bat,’ Tom said.
‘Maybe it fell off its mum,’ said Sophie.
‘Do you think she’ll come back for it?’
‘Not with us here,’ said Sophie. ‘Come on, we’d better keep an eye on it from a safe distance.’
They waited behind a nearby tree for half an hour, peering out every minute or so. The mother bat did not return.
‘It’s past eight. We have to go home,’ said Tom.