Where she goes, they follow. All 76 of them.

A female duck in Minnesota has about six dozen ducklings in her care, a remarkable image that an amateur wildlife photographer captured on a recent trip to Lake Bemidji, about 150 miles northwest of Duluth, Minn.

“It was mind blowing,” the photographer, Brent Cizek, said in an interview. “I didn’t know that a duck could care for that many chicks.”

It’s not unusual to see many ducklings gathered together. Some 20 or 30 have been reported with a single hen. But 70-plus?

“It’s an extraordinary sighting,” said Richard O. Prum, an ornithologist at Yale University.

Experts say the photo, which has been shared among bird conservationists and featured on the National Audubon Society’s website, offers an extreme example of a somewhat common phenomenon in nature. Here’s a look at the story — and the science — behind the striking image.