by Adam Frost
Tom looked impressed, but then his face fell. ‘So Pat’s mum isn’t up there?’
Terry shook his head. ‘No, we need to keep looking.’
They walked along the canal and stopped at the next X on Tom’s map.
Terry held up the detector. ‘Want to try?’ he asked.
‘Definitely,’ Tom said, before Sophie had even opened her mouth.
‘OK, turn this dial here slowly until you hear a noise,’ Terry said.
‘There are definitely bats here,’ said Sophie. ‘I can hear them without that.’
Tom and Sophie peered up into the dark trees overhead. Tom kept turning the dial on the detector.
‘I can’t hear anything,’ said Terry, ‘but the fact that you can means they must be a fairly loud species. Maybe noctules.’
Tom twisted the dial on the detector until it emitted a series of loud pinging noises. He grinned in triumph.
‘And there they are,’ said Terry. ‘Noctules. Oh, I love noctules.’
‘It sounds like a laser gun in a science fiction film,’ said Tom.
‘Or someone twanging a rubber band,’ said Sophie.
‘Beautiful, aren’t they?’ said Terry. ‘Let me have the detector a minute.’
Tom handed it back and Terry quickly connected it to his laptop. ‘Noctules are a big, loud bat. Fast too, about fifty kilometres an hour. And tough – they can survive without food for three or four months if necessary.’
He clicked an icon on his laptop and a series of sound waves rippled across the screen.
‘Look, see how the sound waves are getting closer together,’ said Terry, pointing at the screen. ‘That means he’s increasing the frequency of his call. He’s heard an insect. He’s hunting.’
The bat detector was making higher and faster noises and the sound waves on the screen were getting closer and closer together.
‘What’s happening now?’ Sophie asked.
‘He’s closing in,’ said Terry.
The sound waves were almost on top of each other. Then they smoothed out and there was a series of sharp clicking noises.
‘Now what?’ Tom asked.
There was another clicking noise.
‘He’s eating his dinner,’ said Terry.
The sound waves were getting smaller and flattening out.
‘And now he’s flying out of range,’ said Terry.
Tom stared at the screen for a few seconds and then said, ‘So what would Pat’s mum sound like?’
Terry looked at Tom and smiled. ‘Good question.’ He opened a file on his computer and double-clicked it. ‘Like this.’
Tom and Sophie heard a rapid fluttering noise. The sound waves on the screen were bunched together very tightly.
‘It’s like a bird flapping its wings really quickly,’ said Sophie.
‘Or if you hold a plastic ruler over a desk and flick the end,’ said Tom.
‘OK,’ Sophie said. ‘Now we know what we’re listening for. On with the mission.’
Terry nodded. He handed the bat detector to Sophie. ‘Your turn.’
Sophie smiled and took the detector.
For the next hour, they continued to search up and down the towpath, leaving the marina to hunt along the canal at Camden and Islington. Using the bat detector, they picked up more Common Pipistrelles, long-eared bats and noctules. Behind Regent’s Park, they heard a serotine bat, which made a call that was similar to a noctule’s but slower and less metallic.
They were having so much fun, they almost forgot about their mission.
Then at half past eight, Terry said, ‘OK, I’ve got to get you two home now.’
‘But . . . but . . . we haven’t found any Daubenton’s yet!’ protested Tom.
‘And there are loads of places we haven’t looked,’ added Sophie.
‘Look, if I don’t get you back at a decent time, your mum will kill me,’ Terry said. ‘And if she kills me, our mission will be over, won’t it?’
‘She wouldn’t actually kill you,’ Tom said.
‘She’s not that scary once you get to know her,’ Sophie said.
The three of them walked back to The Ark.
‘I’ll just drop in on your grandad, see how Pat’s doing,’ said Terry, ‘but shall we meet at the same time tomorrow?’
Tom and Sophie smiled and nodded.
‘Operation Find Pat’s Mum,’ said Terry. ‘End of Day One.’
Chapter 8
Tom and Sophie went out with Terry for the next six evenings. On the second evening, they accepted that there were no more Daubenton’s living on the canal, and after that Terry took them to search further afield. They explored nearby parks and nature reserves and city farms. They talked to vicars and explored church attics; they spoke with caretakers and searched through school lofts.
Everybody seemed keen to help them once they understood the nature of the mission.
Sometimes Tom and Sophie used the bat detector; sometimes they could identify the bats by their call or their size or the shape they made when they flew.
On the sixth evening, Terry bent over and examined some bat droppings in a graveyard. ‘Want to learn how to analyse bat poo?’ he asked.
Tom looked at Sophie and shrugged. Sophie shrugged back.
‘OK,’ they both said.
‘You can tell a lot about bats from their poo,’ Terry said, moving the droppings around with a long plastic stick, ‘because all bats have slightly different diets. For example, long-eared bats live in woodlands so they tend to eat more beetles and crickets. Daubenton’s like Pat live near water so they eat more moths and midges. You’ll often see the remains of these insects in their poo.’
‘There’s some poo over here,’ Tom said, crouching down and pushing a brown lump with a stick, ‘but I can’t see any insects in it.’
Terry glanced up. ‘That’s because it’s a dog poo, Tom.’
‘Oh, OK, right,’ Tom said, standing up quickly. ‘Thought it looked familiar.’
‘Each bat species also has different-shaped poo,’ said Terry. ‘Pipistrelle poo is just tiny dots. A Daubenton’s is twice as long and sort of curvy.’
‘So we need to look for curvy poo with midges in it,’ Sophie said.
‘Yep,’ agreed Terry.
He got down on his hands and knees and put his face right up against a few greyish streaks on a gravestone. He sniffed and put his little finger in it.
Tom knelt down beside Terry. Then Sophie sighed and knelt down next to Tom.
‘Hey, Soph,’ Tom said. ‘I’ll be in charge of this assignment. But you can be my number two if you like. Geddit? My number two!’
Sophie glared at Tom, and Tom stopped smiling.
At the end of the evening, after they had explored every tree and every poo in the Camley Street Nature Park, Terry sighed and wiped his forehead. ‘We’re running out of places to look.’
‘Are you saying we should give up?’ Sophie asked.
‘Not give up, but we might have to think about a plan B,’ Terry replied.
‘You mean, we look after Pat ourselves?’ Tom asked. ‘Like we originally planned?’
‘Maybe,’ Terry said.
‘But I thought you said she really needed to be with other bats,’ said Sophie.
‘I did,’ said Terry. ‘She does. Look, let’s have a night off tomorrow and see what we think about everything on Sunday.’
When they got back to the marina that night, Tom and Sophie headed for Grandad’s boat. They went into the darkroom and looked at Pat scuttling backwards and forward in her box. They both took turns feeding her milk and mealworms.
‘It’s great looking after her,’ said Sophie, ‘but what happens when she starts flying?’
‘And she might want to get married and have kids,’ said Tom. ‘Who’s she going to marry stuck in here? Grandad?’
Sophie chuckled. ‘We can’t give up yet, can we, Tom?’ she said.
Tom shook his head. ‘Not until we’ve completed our mission.
’
On Saturday Tom and Sophie headed to the zoo with their parents.
‘What are you going to look at today, kids?’ Mr Nightingale asked, as they went through the staff turnstile. ‘Let me guess – bats?’
‘Not just bats,’ said Tom.
They headed for the Nightzone and, after a brief look at the potto and a quick glimpse at the armadillo, they stood in front of the Seba’s Short-tailed Bats.
‘You can tell they’re not meant to live alone, can’t you?’ said Sophie, as she watched the bats flitting from one part of the enclosure to another and huddling together in small groups.
Tom nodded. ‘A bat needs its friends and family.’
They watched the bats for another couple of minutes.
Then Tom noticed two boxes fixed to the back wall of the enclosure.
‘Hey, look, they’ve got a house back there,’ said Tom.
Sophie smiled. ‘I wonder what’s inside.’
‘And I wonder how you make one,’ murmured Tom. His eyes suddenly widened. ‘Soph, that’s it!’
‘What’s it?’ Sophie said.
‘We’ll build Pat’s mum a house. Then she’ll definitely come back.’
‘What? Where?’
‘Exactly where we first saw her. By the bridge near The Ark.’
‘That’s actually a good idea,’ said Sophie. ‘It’ll mean that, if Pat’s mum is flying past, or her colony changes roost again, they might see a bat box and snuggle in there.’
‘Exactly!’ said Tom. ‘Come on.’
‘Where are we going?’ Sophie asked, as Tom dragged her out of the Nightzone.
‘To find Dad of course,’ Tom said. ‘He can build anything.’
They ran to the large-mammal section, where their father worked. They found him walking across the green towards Gorilla Kingdom, carrying a bucket full of chopped-up vegetables.
Tom told him about their plan.
‘A bat box, eh?’ Mr Nightingale said. ‘Well you’re in luck. I built the one in the Nightzone. I think I still remember how I did it.’
He pulled a notepad out of his top pocket and started scribbling on it.
‘This is what we’ll need,’ said Mr Nightingale. ‘Give this list to Grandad. He can take you to the DIY shop.’
Tom, Sophie and Grandad returned from the local DIY shop with armfuls of wood, pencils and nails – plus a small saw and a bottle of special glue.
Mr Nightingale was already at Grandad’s barge. He’d drawn a sketch of the bat box – a rectangular shape, about thirty centimetres high, with a narrow slot in the bottom that the bats could crawl through. There would be a ladder on the back wall of the box. About thirty Daubenton’s bats would be able to fit inside.
Dad put everyone to work. Sophie helped to measure everything, placing the ruler on the wood and drawing marks around the edges with a pencil. Grandad and Tom made the ladder, with Grandad sawing the wood for the rungs and Tom gluing the sides together.
Soon the bat box was complete.
‘Do we need to put varnish or anything on it?’ Sophie asked. ‘To stop the rain getting in?’
‘No, it’s perfect as it is,’ Mr Nightingale said. ‘We won’t treat the wood at all. It needs to be rough and knobbly. So bats can cling on to the outside and the inside.’
Ten minutes later, Terry appeared.
‘Your grandad phoned,’ he said. ‘Apparently you’ve got something to show me. This must be it.’ He nodded at the brand new, home-made bat box on the table. ‘Did you make that?’ he asked, picking it up gently.
Tom and Sophie nodded.
‘That is a masterpiece,’ Terry said, turning it from side to side.
‘I thought we could put it near the bridge,’ Tom said. ‘Maybe Pat’s mum will see it and move in.’
Terry smiled. ‘That’s a great idea. It’s about a week since they shifted roost. The weather’s got much warmer, so they could well return to their original home – down here where it’s cooler.’ He examined the bat box again. ‘This is a palace. What bat wouldn’t want to live in this?’
Tom, Sophie and Terry were soon sprinting along the towpath. Sophie was holding the bat box, Tom had the toolbox and Terry was carrying a stepladder.
When they reached the bridge, Terry said, ‘OK, where shall we put our box?’
‘Up there?’ suggested Tom, pointing to a nearby tree.
‘It’s not very sheltered,’ said Terry. ‘Bats prefer to be out of the way.’
‘Over there?’ suggested Tom, indicating a smaller tree by the bridge wall.
‘It’s quite far from the water,’ said Terry. ‘Let’s try to get closer to the canal.’
‘How about there?’ Sophie suggested, pointing to a tree that arched over the water. ‘It’s near the canal, and look – it’s got flowers growing under it! They’ll attract butterflies and moths.’
‘Well spotted, Sophie,’ said Terry.
‘That’s quite a good idea, I suppose,’ said Tom grudgingly.
Terry leant the ladder against the tree, wedging the top end under a branch. Then he started to climb up. When he got to the top, Sophie climbed up the first couple of rungs and handed him the box.
‘Hammer and nails,’ said Terry.
Tom scrambled halfway up the ladder and passed Terry the tools.
After a minute or two, Terry said, ‘I can’t seem to hold the box still and hammer in a nail at the same time.’
Tom and Sophie looked at each other.
‘Why didn’t you say?’ Sophie said.
Both Tom and Sophie leapt on to the lowest branch of the tree and pulled themselves up to the next branch and then the next and the next. In a few seconds, they were eye to eye with Terry.
‘We’re pretty good at climbing trees,’ Sophie said.
Terry smiled. ‘Very handy. Tom, you hold the bottom of the box. Sophie, you hold the top.’
Tom moved around to the other side of the tree. Then both Tom and Sophie leant forward, each putting one arm around the tree trunk and the other on the bat box, holding it in place while Terry gently tapped nails into the bottom and sides.
‘Done,’ said Terry.
He started to climb down the ladder.
When he reached the ground, he was startled to see Tom and Sophie standing on the towpath, waiting for him.
‘We’re good at climbing down trees too,’ Sophie explained.
Tom glanced up at the bat box. ‘So what happens now?’
‘Well, it depends,’ Terry said. ‘There’s no point us staying here. The bats won’t arrive till it’s dark. Truth is, the best thing we could do is . . . build another box!’
‘Really?’ Tom said.
Terry nodded.
‘Cool!’ Tom exclaimed.
‘Did you have much wood left?’ Terry asked.
‘Loads,’ said Sophie.
‘The more boxes we can put up there,’ Terry said, ‘the more chance we have of attracting Pat’s mum. We should put up maybe three or four, at different heights and facing different directions.’
Tom, Sophie, Terry, Grandad and Mr Nightingale built another two boxes that evening. Terry, Tom and Sophie managed to fix them both to the same tree trunk before it became too dark to see.
‘OK,’ Terry said, climbing down the ladder. ‘Now let’s get out of here. We don’t want to scare any bats off.’
Tom, Sophie and Terry walked down the towpath and stood next to a bush at least thirty metres away.
Terry turned his bat detector on. It was dusk and the outline of the tree with its bat boxes sticking out was visible in the distance.
Tom and Sophie had brought their special torches. They switched them on and two reddish beams shot through the grey evening light.
Half an hour passed. Nothing happened.
Then Terry’s bat detector made a scuffling, shuffling sound.
‘Daubenton’s,’ whispered Tom and Sophie.
A few bats gathered by the bridge. They swooped down towards the canal, s
kimmed across the surface of the water and took off again.
‘I think that one caught three midges at once,’ Tom said, training his beam on the third bat as it vanished into the sky.
More bats gathered. They also tracked across the water, scooping up insects with their claws and pouches.
Sophie shone her torch on the lowest bat box and then on the other two.
‘They’re ignoring the boxes,’ she said with a sigh.
‘Give them a chance,’ said Terry.
‘There! Look!’ Tom whispered. He was holding the beam of his torch on the lowest box.
A bat was scuttling up the ladder and sniffing at the bottom of the box.
‘Go on, go on, go on,’ urged Terry.
But the bat pushed itself off and disappeared into the night.
‘I don’t believe it,’ said Sophie.
Over the course of the evening, a couple more bats inspected the bat boxes but neither ventured inside.
‘We’ll come back tomorrow,’ Terry said. ‘I’ve got a good feeling about tomorrow.’
‘But how much longer do we have,’ Sophie asked, ‘before Pat’s mum forgets who Pat is?’
‘Lots of time,’ said Terry. But his voice sounded flat and he had a worried expression on his face.
Tom and Sophie followed Terry back to The Ark, feeling frustrated.
‘We’ll just have to build more boxes,’ said Tom, ‘and put them on every tree on the canal. Until there’s nowhere else for the bats to land. That’s GOT to work.’
Sophie nodded slowly, trying to hide her gloominess.
‘Let’s go and give Pat her dinner,’ she said.
Chapter 9
The next evening, Tom and Sophie went to Grandad’s houseboat as usual. They were surprised to see that Terry was already there. Pat’s box was also on the kitchen table.
‘What’s Pat doing out of the darkroom?’ Sophie asked. ‘It’s not time for her to go to sleep yet.’
‘It’s only temporary,’ said Grandad. ‘Terry has some exciting news.’
‘Pat’s going to come with us tonight,’ Terry said.