The unusual sight of a mother duck followed by 76 ducklings has recently made waves, after amateur wildlife photographer Brent Cizek posted photos of the birds on Instagram. Now, new video of the ducks makes it clear just how impressive a feat it is for this mama duck to lead a giant supergroup of waddling babies.

This sighting, on Lake Bemidji in Minnesota, has raised some questions: How did the bird acquire all these ducklings? How is she able to remain in charge of so many? What will become of the ducklings when they grow up?

The dozens of ducklings trailing this merganser hen follow her lead to find food, and she is responsible for keeping them well away from predators, explains Steve Cordts, a waterfowl staff specialist with Minnesota’s Department of Natural Resources. But they are not all hers. She has acquired the ducklings from many broods on the lake to form the group, called a crèche. This phenomenon occurs in several other types of birds as well.

Of a Feather

Many factors contributed to this crèche’s size, say Dave Rave, a wildlife manager and Cordts’ colleague. A late thaw on the lake forced all of the nesting hens to wait until the same time to lay eggs, and mild weather increased the odds that the eggs hatched successfully.

“One thing that struck me about this particular crèche was that all the ducklings were young, and they were all about the same age,” says Rave. “I’ve seen some crèches where the ducklings are of several different ages,” which is more likely after an earlier thaw. (Read about the ducklings on National Geographic’s doorstep.)

But while this crèche is impressive—the average size is around 40 ducklings—about four years ago, Cordts saw an even larger group on the same lake. “It was over one hundred,” Cordts says. “Although they get very hard to count when there’s that many of them.”

The lead hen is probably an older duck that has raised ducklings successfully in the past. At about ten years old, she knows the best spots to forage and how to avoid predators. It’s not known, though, exactly how this Merganser hen acquired so many ducklings in her crèche.

While some theorize that younger hens may voluntarily give their ducklings to such a “grandmother” figure, others suggest that aggressive hens may kidnap and then defend other hens’ broods. It may also be that she picked up ducklings orphaned by inexperienced, first-time nesters, or that confused ducklings started following the wrong hen. (Read about how ducks compete for mates.)

The crèche will stay together for about two months, until the ducklings—already over a month old—start to fledge. At that point the lead hen, recently given the nickname “Mom of the Year,” will no longer need to lead them around.

Fledging Together

When the ducklings start to grow their flight feathers and the crèche mother leaves them behind, the 76 ducklings will most likely stay together in a loose group to forage for fish. Other, and likely smaller, crèches of fledgling ducks on Lake Bemidji may join them.

As fall progresses, Rave says, “they start to build up into really big groups of several hundred birds, and those groups tend to migrate together.”

Common mergansers migrate from throughout North America to as far south as the Gulf Coast. And when they’re about four years old, the female ducklings from this crèche will find mates at their wintering grounds and bring them home to the place where they hatched—Lake Bemidji. For this reason, the Merganser hens on Lake Bemidji are probably related, and the “mama merganser” may actually be the ducklings’ great-grandmother. (Read about the world’s colorful migrations.)

As the ducks grow up, they won’t need to worry too much about Minnesota’s hunting season—they’re legal to hunt, but as fish-eating ducks, they don’t taste very good. There are, however, natural predators such eagles, otters, and northern pike that they’ll need to look out for.

For now, Cizek returns to watch the crèche almost every day. “I originally wasn’t super interested in photographing birds; I was really trying to go out and find bear or moose,” Cizek says.