Boston’s airport has the highest known concentration of snowy owls in New England. Raptor researcher Norman Smith has removed more than 900 of the Arctic birds.

From helping them find mates to bettering their ability to camouflage, marks on animals and birds serve various purposes.

Through binoculars, I could see it was a male snowy owl. His body was covered in thick, white down, offset by a black beak, black talons and a few black dots on his feathers. His head swiveled ...