This was true enough. The normal fighting formation of sphexes was line abreast, which automatically surrounded anything which offered to flee and outflanked anything which offered fight. But here they ascended the mountain in long lines, one after the other, following apparently long established trails. The wind blew along the slopes and carried scent only sidewise. But the sphexes were not diverted from their chosen paths. The long processions of hideous blue-and-tawny creatures—it was hard to think of them as natural beasts, male and female and laying eggs like reptiles on other planets—simply climbed.
"There've been other thousands of beasts before them," said Huyghens. "They must have been crowding this way for days or even weeks. We've seen tens of thousands in Semper's camera. They must be uncountable, altogether. The first-comers ate all the game there was, and the last-comers have something else on whatever they use for minds."
Roane protested: "But so many carnivores in one place is impossible! I know they are here, but they can't be!"
"They're cold-blooded," Huyghens pointed out. "They don't burn food to sustain body-temperature. After all, lots of creatures go for long periods without eating. Even bears hibernate. But this isn't hibernation—or estivation, either."
He was setting up the radiation-wave receiver in the darkness. There was no point in attempting a fix here. The transmitter was on the other side of the Sere Plateau, which inexplicably swarmed with the most ferocious and deadly of all the creatures of Loren Two. The men and bears would commit suicide by crossing here.
But Huyghens turned on the receiver. There came the whispering, scratchy sound of background-noise. Then the signal. Three dots, three dashes, three dots. Three dots, three dashes, three dots. It went on and on and on. Huyghens turned it off. Roane said:
"Shouldn't we have answered that signal before we left the station? To encourage them?"
"I doubt they have a receiver," said Huyghens. "They won't expect an answer for months, anyhow. They'd hardly listen all the time, and if they're living in a mine-tunnel and trying to sneak out for food to stretch their supplies—why, they'll be too busy to try to make complicated recorders or relays."
Roane was silent for a moment or two.
"We've got to get food for the bears," he said presently. "Nugget's weaned, and he's hungry."
"We will," Huyghens promised. "I may be wrong, but it seems to me that the number of sphexes climbing the mountain is less than yesterday and the day before. We may have just about crossed the path of their migration. They're thinning out. When we're past their trail, we'll have to look out for night-walkers and the like again. But I think they wiped out all animal life on their migration-route."
He was not quite right. He was waked in darkness by the sound of slappings and the grunting of bears. Feather-light puffs of breeze beat upon his face. He struck his belt-lamp sharply and the world was hidden by a whitish film which snatched itself away. Something flapped. Then he saw the stars and the emptiness on the edge of which they camped. Then big white things flapped toward him.
Sitka Pete whuffed mightily and swatted. Faro Nell grunted and swung. She caught something in her claws. She crunched. The light went off as Huyghens realized. Then he said:
"Don't shoot, Roane!" He listened, and heard the sounds of feeding in the dark. It ended. "Watch this!" said Huyghens.
The belt-light came on again. Something strangely-shaped and pallid like human skin reeled and flapped crazily toward him. Something else. Four. Five—ten—twenty—more…
A huge hairy paw reached up into the light-beam and snatched a flying thing out of it. Another great paw. Huyghens shifted the light and the three great Kodiaks were on their hind legs, swatting at creatures which flittered insanely, unable to resist the fascination of the glaring lamp. Because of their wild gyrations it was impossible to see them in detail, but they were those unpleasant night-creatures which looked like plucked flying monkeys but were actually something quite different.
The bears did not snarl or snap. They swatted, with a remarkable air of businesslike competence and purpose. Small mounds of broken things built up about their feet.
Suddenly there were no more. Huyghens snapped off the light. The bears crunched and fed busily in the darkness.
"Those things are carnivores and blood-suckers, Roane," said Huyghens calmly. "They drain their victims of blood like vampire bats—they've some trick of not waking them—and when they're dead the whole tribe eats. But bears have thick furs, and they wake when they're touched. And they're omnivorous—they'll eat anything but sphexes, and like it. You might say that those night-creatures came to lunch. But they stayed. They are it—for the bears, who are living off the country as usual."
Roane uttered a sudden exclamation. He made a tiny light, and blood flowed down his hand. Huyghens passed over his pocket kit of antiseptic and bandages. Roane stanched the bleeding and bound up his hand. Then he realized that Nugget chewed on something. When he turned the light, Nugget swallowed convulsively. It appeared that he had caught and devoured the creature which had drawn blood from Roane. But Roane had lost none to speak of, at that.
In the morning they started along the sloping scarp of the plateau once more. During the morning, Roane said painfully:
"Robots wouldn't have handled those vampire-things, Huyghens."
"Oh, they could be built to watch for them," said Huyghens, tolerantly. "But you'd have to swat for yourself. I prefer the bears."
He led the way on. Here their jungle-formation could not apply. On a steep slope the bears ambled comfortably, the tough pads of their feet holding fast on the slanting rock, but the men struggled painfully. Twice Huyghens halted to examine the ground about the mountains' bases through binoculars. He looked encouraged as they went on. The monstrous peak which was like the bow of a ship at the end of the Sere Plateau was visibly nearer. Toward midday, indeed, it looked high above the horizon, no more than fifteen miles away. And at midday Huyghens called a final halt.
"No more congregations of sphexes down below," he said cheerfully, "and we haven't seen a climbing line of them in miles." The crossing of a sphex-trail meant simply waiting until one party had passed, and then crossing before another came in view. "I've a hunch we've crossed their migration-route. Let's see what Semper tells us!"
He waved the eagle aloft. And Semper, like all creatures other than men, normally functioned only for the satisfaction of his appetite, and then tended to loaf or sleep. He had ridden the last few miles perched on Sitka Pete's pack. Now he soared upward and Huyghens watched in the small vision-plate.
Semper went soaring—and the image on the plate swayed and turned and turned—and in minutes was above the plateau's edge. And here there was some vegetation and the ground rolled somewhat, and there were even patches of brush. But as Semper towered higher still, the inner desert appeared. But nearby it was clear of beasts. Only once, when the eagle banked sharply and the camera looked along the long dimension of the plateau, did Huyghens see any sign of the blue-and-tan beasts. There he saw what looked like masses amounting to herds. But, of course, carnivores do not gather in herds.
"We go straight up," said Huyghens in satisfaction. "We cross the plateau here—and we can edge downwind a bit, even. I think we'll find something interesting on our way to your robot colony."
He waved to the bears to go ahead uphill.
They reached the top hours later—barely before sunset. And they saw game. Not much, but game at the grassy, brushy border of the desert. Huyghens brought down a shaggy ruminant which surely would not live on a desert. When night fell there was an abrupt chill in the air. It was much colder than night-temperatures on the slopes. The air was thin. Roane thought confusedly and presently guessed at the cause. In the lee of the prow—mountain the air was calm. There were no clouds. The ground radiated its heat to empty space. It could be bitterly cold in the nighttime, here.