Mr. Sterchi first started photographing the squirrels — running along nearby power lines, balancing on the rail — to show their friends. They soon realized that one was male, with a small notch in his ear. They named him Chip. The other had a noticeably short tail. They called her Little Tail.

“They lived with us the whole winter,” Ms. Buczkowski said. The squirrels packed their den with leaves and branches and dug tunnels to come and go. The couple put out food for the squirrels. (Pecans were their favorite; Cheerios less so.) The squirrels were intelligent. Whenever Ms. Buczkowksi lifted the screen, they ran down the power lines to the window, expecting food. The couple began thinking of their wild neighbors and photo subjects as members of the family.