By Don Lyman
The Boston Globe, February 1, 2019
Adult: An adult great horned owl was photographed in Mount Auburn Cemetery by John Harrison, who named him “Alexander The Great (Horned Owl).JOHN HARRISON
Valentine’s Day, which is right around the corner, is a time for people to celebrate love. But this is also a time of year when another creature is pursuing love. It’s great horned owl mating season in Massachusetts. “Great horned owls are the earliest nesting birds in Massachusetts,” said Wayne Petersen, director of Massachusetts Important Bird Areas for the Massachusetts Audubon Society. “It’s not unusual to see snow on their nests.” Local great horned owls start hooting in December and January. “Hooting can be to attract a mate or to firm up a pair bond,” Petersen said. “The male calls first, and has a deeper call. The female has a softer, more mellow call.”
Males also hoot to let other males know that it’s their territory, he said.
Why do great horned owls breed in winter? Petersen explained their prey is mostly mammals. The time when great horned owls are incubating their eggs coincides with a time when there’s not much food around, as some mammals, such as chipmunks, are hibernating, so it might be hard to feed a family of growing owlets. But by the time the young hatch — in March or April and the snow is off the ground — lots of prey animals are becoming active, so the winter breeding season seems timed to coincide with prey activity. Great horned owls can live 25 to 30 years, and mate for life, but don’t build their own nests, said Petersen. Instead, they use previously built nests, primarily those of red-tailed hawks, but also nests from ospreys, crows, and great blue herons. Red-tailed hawks and great horned owls don’t use the nest in the same season — they swap back and forth. “Some years hawks use the nest, and some years owls use it,” said Petersen.
Asked if a red-tailed hawk would ever try to kick the owls out of their nest, Petersen said, “Nothing tries to kick a great horned owl out of a nest. They are big predators.” Great horned owls grow to about 22 inches tall, with a wingspan of 44 inches, and have sharp inch-long talons. Petersen said they are the largest of seven owl species that regularly occur in Massachusetts, along with short-eared owls, screech owls, saw-whet owls, barn owls, long-eared owls, and barred owls. Great grey owls and snowy owls are bigger, but they are transient visitors to the state. Wildlife biologists who work with great horned owls, such as banding chicks, have to wear thick gloves and hard hats to protect themselves from attacks by the adult birds, he said. Great horned owls usually lay two eggs, which take about a month to incubate. The eggs hatch in March or April. The young usually leave the nest and learn to fly — a process called fledging — by late May, about five weeks after hatching, and master flying nine to 10 weeks after hatching. Between the time the juvenile owls leave the nest and the time they learn to fly, they hang out in branches in the forest canopy, Petersen said. But these young “branchers,” as they’re called, can get into trouble and fall from the tree. The parents usually continue to feed and care for the chicks even while they’re on the ground. John Harrison, an author and birder/photographer from Medford, said that last April a juvenile great horned owl fell out of a tree in the Fresh Pond Reservation in Cambridge. Harrison was one of several people who monitored and photographed the juvenile. The parents continued to feed the baby owl and eventually it was able to climb safely back into the trees. Harrison and his friend, Kim Nagy, wrote a children’s book about the experience: “Skylar’s Great Adventure.”
Like most owls, great horned owls are active primarily at night, and are efficient hunters. “They are sinister predators, because they can see and hear well in the dark, fly silently, and grasp prey with their long talons,” Petersen said. “They can take big stuff — squirrels, rats — practically anything they want to. But they also eat smaller animals like mice and chipmunks.” Petersen said they’ll even eat skunks. “Sometimes you’ll smell a skunk odor up in a tree,” he said. “That’s usually a sign that there’s a great horned owl nest in the tree.” They’re not inclined to hunt birds, but will occasionally take crows at night from communal winter roosts, and will sometimes pluck baby shore birds, like terns, from their nests. Owls regurgitate pellets, which are composed of indigestible body parts, like bones, skulls, and fur, said Petersen. “Looking at owl pellets is a great way to get a sense of what they’re feeding on.” Adult great horned owls don’t have any natural enemies, he said, but raccoons can eat their eggs. They are also vulnerable to being hit by cars, or electrocuted on power lines.
Above: Roxane (Alexander the Great's mate) and her owlet were photographed in Mount Auburn Cemetery. JOHN HARRISON
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