saiga antelope mother calf usfws USFWS/Flickr (CC BY 2.0)

You're a gazelle.

You're a gazelle who's about to have a very bad day.

That's because as you and your herd are going along your business on the Ustyart Plateau of northern Uzbekistan, you come across a ridge in the ground. You keep running alongside it, then it disappears. So you think nothing of it.

Then you find another ridge in your path. You don't like having things in your way, so you veer a little to follow it, figuring it will disappear soon too.

Then you find yourself — and the rest of your herd — at the bottom of a ditch.

That's how scientists think real structures called desert kites worked. They were built over a huge span of time, from 8,000 to 2,500 years ago across a swath of land from the Middle East to Central Asia.

They're basically gigantic traps. We heard about them in a National Geographic story, but they were first noticed during World War I. Desert kites are hard to see from the ground — they just seem like random ditches and ridges.

But from the air, the patterns they make begin to pop out. They look a bit like a grade-schooler's drawing of a tulip with the middle petal missing. In this satellite image, the outer edges of two desert kites are highlighted.

two trapsGoogle Maps

People have speculated they were used for everything from religious ceremonies to camel fences. But the current theory is that they were elaborate funnels for trapping herds of wild gazelle and similar animals — as many as a hundred at a time.

For the last few years, scientists from a range of fields have begun to study them in earnest. They've worked on mapping them, figuring out how they may have been used, and even estimating the impact the technique may have had on the animals it caught.

You can see how desert kites worked in this video beginning at 4:35.

Desert kites are pretty widespread: more than 5,000 have been spotted. But scientists have been able to identify some local differences in precisely how they're designed.

The desert kites were still used by locals as recently as early in the 20th century, but they aren't much of a risk to wildlife now. That's because there aren't huge herds roaming the plateaus these days.

For example, saigas, a type of lumpy-nosed antelope, died at incredibly high rates last year due to a mysterious disease. Even over the past three decades, residents have noticed sharp declines in the animals around them.

But at the peak of their use, scientists say, the desert kites could have helped push some species to extinction.

The problem with slaughtering huge portions of the population en masse isn't just the number of animals you lose. It also changes what the population looks like.

Instead of picking off the oldest or the slowest or the sickest or the injured — the ones who can't outrun an arrow or a bullet — this type of hunting kills off more adults and young adults. That means there are fewer animals reproducing and makes the population more fragile.

When scientists looked at the skeletons of animals buried near desert kites, they found exactly this pattern: lots of healthy animals, some just a few months old. They believe the kites contributed to the extinction of the Persian gazelle, which hunters may have been targeting.

But we use now a surprisingly similar technique to harvest the oceans. A purse seine is a giant net — as much as a mile long — that can catch a whole school of fish in one go. It's great for efficiency, but helps contribute to a global problem of overfishing. Global fish populations have been declining since 1988.

No matter what happens to the oceans' fish, archaeologists will never study purse seines the way they've been able to study desert kites. But there's still more to learn from these giant arrows pointing to nowhere — and perhaps how to live within the planet's resources is one of those lessons.
