Somerville resident James O'Keefe photographed what appears to be a snowy owl perched on the roof of the Healey School in the Ten Hills neighborhood of Somerville.

Dubbing the owl Hedwig in a Twitter message, O'Keefe has shared his photo with Somerville Patch. Hedwig is Harry Potter's messenger owl from the book series that became a movie series. Like the Healy School bird, Hedwig is a snowy owl.

According to National Geographic, snowy owls like to eat lemmings, and a male owl can eat three to five lemmings every day. When not eating lemmings, the owls will supplement their diets with rabbits, rodents, fish and birds.

Unlike most owls, which are nocturnal, snowy owls are diurnal, according to National Geographic, which means they're active during the day.

Male snowy owls get whiter as they grow older, and female snowy owls get darker, the scientific publication says.

According to the website owlpages.com, the snowy owl's main habitat is the arctic tundra, but their territory sometimes moves south into the northern part of the United States. The website says that, "[d]uring southward movements they appear along lakeshores, marine coastlines, marshes, and even roost on buildings in cities and towns."