So why hadn’t he seen one yet?

The pigeons he remembered had all been large, noisy and brightly coloured, but he knew there were smaller species too, some of them quite well camouflaged. They hardly needed to be silent and invisible, though, here of all places. And there had to be thousands of them.

He said, ‘Can we stop here for a while? Maybe we’re scaring them with all the noise.’

Grant nodded. ‘That’s worth a try.’

Prabir stood motionless for ten minutes, staring up into the branches. He could hear other birds in the distance, and a constant hum of insects, but nothing like the discordant clacking he remembered.

Grant couldn’t resist needling him. ‘So where are they, eagle-eyes? You have my advantage in both youth and experience; if you can’t see them, we might as well go back to the boat.’

‘Don’t tempt me.’ He had a better idea, though. ‘Have you got a camera on you?’

‘Yeah, of course.’

‘Can I borrow it?’

Grant hesitated, then handed it to him.

He examined it carefully. ‘How much did this cost?’

‘Five hundred euros. Which is well above my personal definition of “disposable”. Why? What are you planning to do with it?’

Prabir commanded her loftily, ‘Be patient.’ Five hundred euros meant that the lens would give a much sharper image than his notepad’s camera, and the stabiliser would be a laserring system, not a trashy micro-mechanical accelerometer.

Grant brushed the debris off a fallen trunk and sat down. Prabir set the camera to the widest possible angle, aimed it at a tree twenty metres away, and recorded sixty seconds of vision.Then he passed the data to his notepad through the infrared link.

The program he needed was three lines in Rembrandt, his favourite image-processing language. As he watched the result on the notepad’s screen, Grant saw the expression of delight on his face and came over to see what he’d found.

Outlined in fluorescent blue by the software, half a dozen small green-and-brown birds moved along the branches. Prabir glanced up from the screen to the tree, but even now that he knew exactly what to look for, he couldn’t see the birds for himself. The software was only identifying them in retrospect by comparing hundreds of consecutive frames, and even then it sometimes lost track of their edges against the pattern of leaves.

Grant complained indignantly, ‘You don’t know how galling this is. I grew up on smug biologists’ jokes about pathetic computerised attempts at vision.’

Prabir smiled. ‘Things change.’ Grant was probably only ten years old than he was, but the idea seemed as quaint to him as jokes about heavier-than-air flight.

‘Can you replay it?’

‘Sure.’

As she watched the scene again, she mused, ‘I’ve seen stick insects with that level of camouflage. And some predatory fish. But this is extraordinary.’ She laughed and swatted something on her neck. Prabir had expected her to be elated by their find, but the birds’ proficiency seemed to unnerve her.

He struggled to recall the images Madhusree had shown him back in Toronto. ‘You think this is the pigeon that turned up in Ambon nine months ago?’

Grant nodded. ‘We’ll need specimens to be sure, but it looks like it.’

‘But how did you know it would be here? I thought no one had traced it back from the bird dealer.’

‘They hadn’t, but this seemed the most likely spot. I can’t think why no one else looked here. Maybe it was just prejudice: the Bandas aren’t wild, they aren’t pristine, they aren’t havens of biodiversity. How could a new species possibly be born in a place that was so “barren”?’

‘You tell me.’

‘I will, when I know.’

Grant had brought a tranquilliser gun. Prabir improvised software to display the outlines with the minimum possible time lag, but it still took them three hours to hit their first target. As he picked the sleeping bird out of the undergrowth, he reflected uneasily on the possible source of its mutations. He still believed it was more than likely that he was looking at a recent descendant of a Teranesian migrant, but if it had brought along a mutagenic virus that could cross between species, tens of thousands of people were potentially at risk. The virus might have taken eighteen years to leap the biochemical gulf between butterflies and birds, but birds were notorious for harbouring potential human diseases. He wished he could get some straight answers out of Grant; it was one thing to avoid starting groundless rumours, but she owed him an informed opinion on whatever it was she thought they were dealing with.

They returned to the boat at dusk, grimy and exhausted, with blood from four pigeons. Prabir looked on as Grant prepared the samples for analysis; the preservative that had kept them stable in the heat had transformed them into blobs of puce jelly.

He said, ‘Do you know anything about the species that used to be here? I don’t mean prior to the Dutch; just ten or twenty years ago.’

‘There’s a 2018 report that mentions half a dozen sympatric species of Treron, Ptilinopus and Ducula.’

‘ “ Ducula”You’re making that up.’

‘No, they’re the big ones. Imperial pigeons.’

‘So what does “sympatric” mean?’

‘Sorry. Co-existing, sharing territory.’

Prabir nodded, ashamed at his laziness; the child who’d named Teranesia wouldn’t have needed to ask. He’d never studied European classical languages, but everyday English had inherited all the clues: just hybridise ‘symmetry’ and ‘repatriate’.

Grant said, ‘Treronare green, but the others are usually brightly coloured, presumably for the sake of mate recognition. The theory is, that’s how they formed separate species in the first place: runaway sexual selection based on plumage, overriding any need for camouflage in the absence of predators.’

‘So where have they all gone?’

She shrugged. ‘Maybe the bird trade wiped them out. The prettiest fetch the highest prices, and they’re also the easiest to catch.’

Prabir wasn’t so sure; fruit pigeons weren’t exactly birds of paradise. Still, times must have been hard after the war, and maybe there’d been enough of a market to make it worth hunting them down.

Grant pulled open a panel on the rack of analytic equipment, and pushed one of the tubes of blood on to a spike. ‘Now we wait.’

Prabir went for a swim in the deserted harbour, staying in the water until it was so dark that he began to wonder what he might be sharing it with. He’d forgotten to bring a towel out with him, so he sat on the deck for a while to avoid dripping all over the cabin. When he walked back in, Grant glanced up from her workbench, taken unaware. He went over to his bunk to put on a T-shirt.

He called out, ‘Any news?’

‘I’ve got all the sequences.’

‘And?’ He approached her. ‘Is it the same species as the one they found in Ambon?’

Grant replied hesitantly, ‘One of our sequences is almost identical to the Ambon data. And all four have the same novel blood proteins as the Ambon bird.’

Prabir cheered. ‘So you were right: you found it in the wild. Congratulations!’ Grant didn’t look particularly pleased, though. He said, ‘What else?’

She glanced down at her notepad. Prabir could see strings of base-pair codes and a cladogram. ‘They also have genetic markers in common with some of the uncamouflaged species we assumed were gone.’

Prabir tried to make sense of this. ‘You mean, they weren’t wiped out, they started breeding with each other?’

‘No, there’s no evidence of that. Each individual specimen we collected shows signs of a distinct recent ancestry. I’m not even sure that they’re not still separate species.’

‘Now I’m confused.’ He laughed. ‘They look identical, they share exotic blood proteins, but you think they have completely different lineages?’

Grant spread her hands on the bench. ‘I can’t be certain, but it looks to me as if they’ve all converged on the same set of traits, within a couple of generations, without interbreeding. Something has given rise to the same genes for the blood proteins and the camouflage, independently, in at least four different species.’