The Tap and the Hollow

The clip had been paused for almost a minute, and the animal on the screen was staring back at them with two enormous orange eyes.

"It looks like three different animals got into an argument and lost," Maya said.

"That's an aye-aye," Soren said. "Madagascar. It's a primate. Like us, sort of."

"That is not like us."

He pressed play. The aye-aye reached out one finger, a long thin finger, much longer than the others, and began tapping the bark of a branch. Tap tap tap. It moved a little. Tap tap tap again. Its ears swiveled forward, huge and bare, like two satellite dishes made of skin.

"What's it doing," Maya said. It was not really a question. She leaned in close to the screen.

"Looking for grubs, the narrator said."

"But it's not looking. Its eyes aren't even on the branch." She rewound it ten seconds and watched again. "Look. The eyes go anywhere. The ears stay locked on the tapping. It's not looking, Soren. It's listening to its own knocking."

Soren had his notebook open on his knee. He wrote down tapping and ears not eyes. "Listening to what, though. It's just tapping wood."

"Knock on the table," Maya said.

"What?"

"Knock on the table. Where it's solid."

He knocked. A dull flat thock.

"Now knock on the part over the drawer. Where it's empty underneath."

He slid over and knocked again. The sound came back higher, looser, with a little room in it. A hollow sound.

They both went quiet. On the screen, the aye-aye had stopped over one spot and was tapping it over and over, faster now.

"It can hear the hollow part," Maya said. "Inside the wood. Where the grubs chewed tunnels."

Soren rewound again, because he needed to see it more than once before he would say it out loud. The aye-aye tapped, moved, tapped, moved, then stopped. Stopped exactly. Then it leaned in and gnawed through the bark right at that spot, and it stuck the same long finger into the hole and came out with something pale and wriggling.

"It found the tunnel by sound," Soren said. "It knocked along the branch until the knock changed, and the change told it where the empty part was. Then it dug there."

"It's seeing inside the tree," Maya said. "With knocking."

"With knocking and those ears."

They looked at the screen together. The narrator's voice was saying something about it being the only primate known to hunt this way, Maya stood up so fast the laptop wobbled. "I want to try it."

"Try what."

"The trees. Outside. There's the old apple tree with the dead branch. Come on."

So they went out into the backyard, which at night was bigger than it was in the daytime and quieter, and the porch light only reached so far. Soren brought his notebook, and a pencil, and tucked them under his arm.

The apple tree had two big branches they could reach. One was live, thick, full of spring. The other had been dead two years and nobody had cut it down.

"Knock on the live one first," Soren said. "So we know what solid sounds like."

Maya rapped it with one knuckle. Thock. Tight. Close. The sound went into the wood and stayed there.

She moved to the dead branch and knocked. The sound was wrong, in the interesting way. Looser. A little hollow in it, the table-over-the-drawer sound.

"Dead wood dries out," Soren said. "It cracks. There could be space in there. Or bugs." He was writing in the dark, not looking at the page.

"Don't tell me where," Maya said suddenly.

"What?"

"Close your eyes. Don't look at the branch. Just knock along it and listen. Find the hollow part with your ears, not your eyes. Like it did."

Soren closed his eyes. It felt strange, standing in his own backyard with his eyes shut, knocking on a dead branch like he was asking it to let him in. Thock. Move a hand-width. Thock. The same. Move again. Thock.

And then his knuckle came down and the sound opened up under it, round and empty, a little drum, a little room in the wood where the solid sound had been.

He stopped. He didn't open his eyes.

"Here," he said. "It's hollow right here."

"Mark it. Keep your eyes shut."

He pressed his thumb flat on the spot. Then he opened his eyes and looked.

Under his thumb, where the bark had peeled a little, there was a hole. A tunnel, the width of a pencil lead, bored clean into the dead wood. Something had lived there. Something had eaten a road through the inside of the branch, and the road had a shape, and the shape had a sound, and he had heard it with his eyes closed.

"You found it," Maya said. She was grinning so wide he could see her teeth in the dark. "You found the inside of the tree by knocking. You just echolocated."

"It's not that good. The aye-aye does it way faster, in the dark, on a branch full of tunnels."

"But it's the same thing. It's the exact same thing your finger just did." She put her own hand on the branch beside his. "There's a whole map in here we can't see. The grub made it. And the only way in is sound."

Soren knocked again, two inches over, eyes open this time. Solid. Then back to the spot. Hollow. Solid. Hollow. He could do it on purpose now. He could read the branch like a page he was learning the alphabet of.

He moved his thumb off the tunnel and knocked once more, somewhere new, somewhere he hadn't tried, and the sound came back loose and round and full of room.

"There's another one," he said, and reached for it.