A shimmery blue butterfly called Xerces once fluttered among San Francisco’s sand dunes. Then people started building . . .

Grand homes.

Posh museums.

City parks.

Soon the butterfly’s habitat was gone. And so was the butterfly. The species, called Xerces blue, died out in the early 1940s.

The only Xerces blues left are dead specimens. Preserved examples display the butterfly’s blue wings with white spots.

But that gave scientists something to go on. Some who work with San Francisco’s California Academy of Sciences wanted to bring back the blue. They studied genes from dead butterflies. Some of these were 100 and even 150 years old. Genes helped them solve a puzzle.

A silvery blue butterfly lives south of San Francisco. Scientists learned that butterfly could live well in the place Xerces blue left behind. It isn’t quite Xerces blue . . . but it’s close!

But there was more work to be done. The substitute blues needed a suitable habitat. People worked to restore dunes in Presidio National Park. They planted deerweed, a blue butterfly’s favorite food.

Meanwhile, wildlife experts collected dozens of silvery blues. They marked them for identification. Then they carefully transported them to San Francisco. Along the way to their new home, the butterflies slurped drops of fruit punch-flavored Gatorade.

In April, scientists released the silvery blues into the park.

It doesn’t count as reversing extinction. But silvery blues will pollinate what Xerces blues once did. They’ll eat what Xerces blues once ate. And they’ll be eaten by what once ate their long-lost cousins.

Why? People care for God’s creation by providing habitats for displaced species.