A favorite winter activity in Riverview Park is looking for great horned owls.
Photo: Wikimedia Commons
Winter provides surprising opportunities in Riverview Park: There is no better time to explore the park’s landscape, tree shapes, and animal behavior. Although it gets dark early, the park is still open and hiking in the dark is fascinating—even mysterious. A favorite winter activity is looking for great horned owls (GHO).
Starting in December, you could listen for GHO as they begin courtship, mating, and nesting. Great horned owls mate for life and the pair resides in the same two to four mile area year round, however they only live together while raising their young. Male owls can be heard hooting: it’s their way of warning other males about their territory and renewing their relationship with their mate. Active courtship doesn’t last long, but then the owls are already acquainted! In mid-December, park visitors witnessed a male and female cozying up in an evergreen, so it appears that the process is already underway.
Simultaneous to courting and mating, the owls establish a nest. GHOs do not build their own. They take over another species’ space, a hawk or squirrel’s nest, for example, or they may move into a tree or building cavity. They move into a new nest each year, so it’s a challenge for park users to find the owls’ new digs.
Typically there are two eggs and incubation is between 21 and 35 days. The eggs must be kept warm or they may not hatch. Given the time of year, the female is usually on the nest and the male will bring food. Chicks’ eyes open on about day 10 and soon after, they are avid witnesses to everything happening around them. They will remain in the nest for about six weeks, fledge in April, and within a few weeks, leave to find their own territory.
For the last two years, Riverview visitors have been delighted to view GHO nests, with two owlets each, immediately next to the road. The huge amount of attention paid to the nests can be concerning as owls will attack when threatened. This past October, while backpacking in Colorado, a GHO came within five feet of my head as I bedded down for the night in what appeared to be an unoccupied meadow.
Because owls’ feathers enable them to fly without making a sound, any encounter will occur without warning. As the grip in their sharp talons is 10 times the grip of a human, contact can be very dangerous. Thankfully, our urban birds seem to be accustomed to, and tolerant of, our interest. In fact, the owlets seem to find humans as interesting as we find them.
Other interesting facts about the GHO:
- GHO horns are not their ears; those are found on the side of the head and they are asymmetrical, which means their ears are located at different heights on their head. This allows their ears to pinpoint the location of sounds in multiple dimensions.
- The eyes of an owl are not true “eyeballs.” Their tube-shaped eyes are immobile, with binocular vision, which focuses on prey and increases depth perception. It’s why owls have to turn their heads to see.
- Owls can rotate their necks 270 degrees. A blood-pooling system collects blood to power their brains and eyes when neck movement cuts off circulation.
- A group of owls is called a parliament.
- An owl has three eyelids: one for blinking, one for sleeping, and one for keeping its eyes clean.
- Owls consume their entire prey, then their digestive system separates the inedible parts, which the owl will spit back out into what’s called a pellet.
There are at least two pairs of GHOs in Riverview Park. They can be spotted in the treetops, now that the leaves are gone. On your next winter hike, make note of mobbing crows; this is one possible sign of a nearby owl nest. Also, watch the ground for bird poop and owl pellets, then look up. You may find an owl looking down.
Nancy Schaefer is a City of Pittsburgh Park Ranger in the Northside’s Riverview Park.