Humans haven't had practice, but birds are veterans of mass extinction

Birds have made it through five.

By Jim Williams Special to the Star Tribune

August 24, 2021 — 10:55am

If this climate business is indeed the beginning of the sixth mass extinction of life on Earth, as some people say, don't worry about birds. Better to worry about us humans, you and me.

There have been five previous mass extinctions. In total, they wiped away 99% of all species that ever existed. But not birds. (Humans weren't here yet.)

Birds survived all five in one form or another, eventually becoming the birds we see today.

The most recent extinction, known as the Cretaceous-Paleogene event, happened 65 million years ago.

The cause of that was either the infamous asteroid, 6.2 miles in diameter, that whistled down onto the Yucatán Peninsula in Mexico, or massive flows of lava in Siberia. The latter theory has fewer proponents.

Both created significant long-term changes to land, air and water.

Many people think we're in a new mass extinction, the sixth, said Robert Zink in an e-mail interview. Zink, presently a faculty member at the University of Nebraska, previously taught ornithology at the University of Minnesota.

"People believe it's being caused by us changing the environment faster than plants and animals can adapt, " he said, adding parenthetically that viruses seem to be doing just fine.

"Whether our planet is changing faster than it ever has is tough to know," he told me.

"Twenty-one thousand years ago there was a mile-thick glacier where your house stands. The glacier isn't there anymore, so global climate change isn't new, but it might be a lot faster now because of us,' " he said.

Modern bird species, like those you see in your yard, stem from that 1% of life that survived all five events. Eventually evolution produced new life forms — dinosaurs, then feathered dinosaurs which led to the 10,000-plus bird species we currently enjoy.

"There is debate about whether most modern birds evolved after the cataclysm or if there were lots of bird species present before the asteroid hit, many of them surviving," Zink said.

We do know that opportunity certainly existed on the outcome side of extinction number five.

It eliminated 80% of the life that had survived or evolved to that point, so opportunities for survivors were massive. Birds would have adapted to fill environmental gaps.

I asked Zink if any extant bird species could be traced back that far.

No one knows, he told me. "It's complicated," he said.

Usually, we expect species with small ranges to go extinct before species with larger ranges, he said. Or, we find that ecological specialists, narrow in food or habitat preferences, are perhaps more vulnerable.

We create vulnerability every time we modify a natural landscape, the landscape to which a bird belongs. We change habitat or eliminate it, leaving birds to do the best they can.

How unreal that we humans on our wristwatch time scale could be agents of change previously measured in geologic terms.

Worry about birds? Birds have survived the previous extinctions. They will survive a sixth if that's what they must do. For birds, it's not their first rodeo. Some species will disappear. Evolution will take advantage.

For us? Well, extinction number six would be our first go-round. Would we do as well as birds? Let's hope we never find out.

Lifelong birder Jim Williams can be reached at woodduck38@gmail.com.