The foliage here was strange. Vines made convoluted turns, as if trying to find a way out of their thick mats. Small, unseen animals clattered and called in the canopy. Birds gave fluttery songs, not like Earthly chirps. Then they heard ahead a low, ominous hum and circled it. A dense clump of webbed brown plants teemed with brightly turning leaves that sounded like bees. Cliff could see no role for this in plant dynamics, unless—“Maybe they’re windmills generating power,” he whispered to Irma.

“For what?”

“Dunno.”

They skirted the humming network, which was a hundred meters wide. He wondered if this artificial ecology used directly generated electrical power somehow, reactors and plants, and not just solar energy. The whole structure could be a giant electrical grid. Only a few meters away lay the high vacuum of space, and the understructure of metal could conduct electricity to distant points. For the usual question—why?—he had no answer.

“There’s some odd noise that way,” Terry said, pointing left. A clatter, some yips and snorts. They followed his lead.

After a few minutes Irma said, “Over there, a hill. Let’s get up in those trees to survey.”

They found a slight rise of a few meters and shimmied up the zigzag trees at the top. Howard stopped halfway up and whispered, “The birds.”

Cliff worked his way out on a limb that kept jabbing him with tiny spikes, the big tree’s defense against some sort of predator. He got a view of a distant meadow where odd things hovered. Four aircars, holding a meter or two above the emerald green. Inside their open tops were two or three of the Bird Folk. The aircars moved in a circling path, and Cliff saw their prey—a large thing that dodged across the meadow, hemmed in by the aircars. It had three legs and danced away from the encircling hunters, its big hairy head jerking around, seeking an escape.

A lance arced out from one of the aircars and hit the big animal in the haunch. It yipped, a high insulted cry, and dashed away. A big Bird stood up in its aircar and threw another lance at it, missed. The aircars rushed around in some kind of pattern, weaving in and out as if this was a game, or some ritual. The animal yipped again and screamed when a lance caught it in the middle.

It collapsed, gasping so loud, Cliff could hear the plaintive cries. Another lance ended that. The thing slumped.

The Bird Folk landed and Cliff wondered at the vehicles’ soundless grace. Were they magnetically suspended? That made sense if they carried powerful electromagnets in their thick undercarriage. The Bowl’s conducting frame a few meters below the meadow would provide the surface that opposed the magnetic fields, allowing the aircars to ride on the magnetic pressure.

“That thing’s a carnivore,” Irma whispered. “Mostly bone and muscle. The birdies are hunting for sport.”

She was right, Cliff saw. Nine of the Birds had formed a circle around the dead creature and did an odd dance, strutting in, whirling, dancing out with spindly arms raised, making quick leg movements. Then came a honking shout. They circled the beast, raised the lances they had pulled out of the carcass, and hooted again.

It looked primitive and yet understandable. Terry said, “They’re like primordial hunters!”

Howard said, “They’re not using impact weapons, like high-caliber guns. I saw some with long spears, arrows, a flung garrote.”

Irma said, “Maybe low impact because they don’t want to damage the underpinning of the Bowl? It’s only a few meters down in spots.”

They nodded and climbed down, moving away from the Bird Folk. Cliff realized that this immense world was a park, in a way. For the Bird Folk.

They spent hours working through the dense vegetation, returning to pick up their gear, then moving on to explore further. It was too risky to leave anything behind—except for the sailcraft, their escape route into the desert lands.

Cliff and Irma took note of the many life-forms they saw, including a long thing like an armadillo. It crawled without legs, using its sliding plates of armor to inch forward. “An armored snake,” Irma said. Terry wanted to kill it for meat, but Cliff was unsure it would be edible. And he hated to kill creatures on spec, even when they were hungry.

They found enough of the nasty lizards lurking near streams and shot them. They were aggressive but stupid; it was simple to kill them. Aybe gathered dry wood to keep their smoke down. As they ate the greasy lizard meat over a low fire, they tossed around ideas about the Bird Folk, and what they had seen. Not reassuring, no.

They napped, got up with the usual aches from sleeping in the open, and after a breakfast of more lizard, moved on into denser woods. This was a search-and-understand mission, and Cliff moved carefully, not letting the uncertainties get to him.

A distant high noise came rolling through the tall trees as they moved forward. A skreee came from their left and they cautiously moved that way, faces puzzled. Some bass rumblings, then more skreee. They saw a broad clear area and circled it, Terry gesturing to keep low.

A chattering alarm burst out in the branches high above them. Cliff felt his pulse rate rise as he duck-walked forward through low brush. The whole forest was alive with excitement and arcing above the din came the shattering calls he recognized as those of primates they had seen before. Monkeys, though larger and stranger. But the skreee sounds had structure, chopped notes floating on the underlying base line, like sung words. These were different primates, riffing up in the high canopy.

He peered through the ropy strands of a vine plant. Much movement. He brought up his binoculars and studied the moving figures.

The Bird Folk. On foot this time.

About two hundred meters away, moving right to left across a broad, rocky plain. They ran in long loping strides, eight of them, carrying instruments in their long arms. Their feathers rippled with flowing patterns of yellow and magenta. Their heads were tilted back, which pointed their long, broad noses forward, their two large eyes glittering. Knobbed legs articulated gracefully, eating up the ground between them and their prey.

Bunches of running figures were nearer to Cliff. Primates, running with their own loping grace. The primates were tall with long arms and even longer legs, running it seemed from a stand of zigzag trees several hundred meters to his right. Their angular heads jerked around, looking back at the birds, who were angling toward them from farther away. Cries spilled from the primates—harsh, barked shrieks. They ran faster and broke into groups of threes.

At first Cliff had thought the ragged, fleeing band were, somehow, humans. But these were primates nearly as tall as the Bird Folk, and had four arms. They ran in clumps of three, the one behind turning to fire something that looked like a crossbow at the Bird Folk. The shots were inaccurate and the Bird Folk dodged them anyway. The primate that fired then ran ahead while a companion in the group of three stopped, aimed, fired. The one in the middle was reloading.

Arrows flew everywhere. Primates and Birds shrieked and howled and chattered—a din.

An arrow hit one of the birds, but it simply lodged in the thick feathers. The Bird plucked it out and tossed it away. Then the primate ran on and the next one stopped to fire, a classic delaying tactic. This shot hit home. A Bird went down in a tangle of legs.

A long, hooting cry came from the Bird Folk. Angry rumbles came from the surging Birds. They sped up, long legs taking great bounds. They closed in on the primates and swept to both sides, a flanking pincer movement.

Something bright flashed from the huge running Birds, and a loud boom rolled across the open plain. Several fired at the same time, and primates burst into flame. Shrieks, bodies falling, limbs jerking.