Employees of the Pepperell Mill Campus in Biddeford were surprised to find a mallard duck nest on the roof of the sprawling brick mills. The duck may also be surprised to find herself guarding her 10 eggs several stories above the Saco River.

“You might be thinking ‘why would a mother duck lay eggs on a roof when the ducklings can’t fly?’ We’re wondering the same thing, and we’re willing to bet this is a first-time mother duck,” Pepperell mill management wrote in their latest newsletter. “We’re very worried that momma duck is going to lead the ducklings to the river and they’re going to fall off the roof, so we’ve contacted the Maine Warden Service for their help.”

Eight of the 10 duck eggs are grouped in a nest atop the Pepperell Mill Campus in Biddeford.

A mallard duck laid her eggs in a raised rooftop garden planter at a renovated mill in Biddeford.

Mill employees placed a fence around the nest – which sits atop a raised rooftop garden planter – so the ducklings can’t wander away once they hatch. The mother can still fly out and get food, according to the newsletter. The ducklings are expected to hatch at the beginning of June.

“The day they hatch, the game warden will lead them safely to water,” the newsletter says.

Mallards can live in almost any wetland habitat, including lakes, ponds, city and suburban parks and residential backyards, according to the Cornell Lab of Ornithology. They are known to be strong fliers, traveling as fast as 55 mph. Mallards typically nest on dry land close to water, often concealing the nest in overhanging grass or vegetation.