The best time to see great horned owls is during the nesting season. Mating usually begins in January or February. Courtship usually begins with an intimate conversation between prospective mates that can often be heard from a great distance. This is followed by a little foreplay, the birds rub their beaks together and preen each other, and then it is time to find a nest. Great horned owls do not build their own nest they borrow someone else's, usually a hawk, crow, heron or squirrels. Once the eggs are laid the female stays on the nest night and day and incubates them.
While the female great horned owl sits on the nest incubating her clutch of 1 to 5 eggs the male spends his days perched near by. When perched the pattern of the feathers on the stomach and chest help it to blend in and camouflage itself next to a tree trunk. This is helpful because any hawks that spotted the owl resting during the day would most likely attack it. Crows also pose a problem during the day. The owls have very little to fear physically from the crows but if spotted the crows will usually mob the owl. This means that they will dive and squawk at the owls which will alert any prey or other predators in the area. Crows are the best way to find owls when it is not nesting season, just follow their racket.
The males job is to bring home the bacon, or in this case mouse, rat, squirrel, rabbit, skunk, bird or other prey species, of which there are at least 250 different types identified. They are ambush hunters, meaning that they perch on a branch or snag until they see or hear some prey below then they swoop down silently killing the prey with their talons.
Like all raptors, great horned owls swallow their food, it's tough to chew if you don't have teeth. If the prey is small enough they will eat it whole but if it is larger, the preferred food of great horns is rabbit, then the owl will use its talons to hold the food and grab it with its curved beak, pulling back with its strong neck muscles to rip the meat into bite size pieces. They will usually eat everything, even though they can not digest bones, fur or feathers. Six to ten hours after eating the owl will regurgitate the indigestible material in the form of an owl pellet.
After 26 to 35 days the eggs finally hatch. The young owl chicks are covered in white down feathers. At this point the female may leave the nest for a short period of time however she stays close so that she can protect the helpless chicks and help to keep them warm, especially in Minnesota where the eggs can hatch in February when the temps are often below zero.
Each night or morning the adults deposit food that they have caught into the nest. As the chicks have gotten larger mom spends less time at the nest. She still comes back to feed the young ones who do not yet have the strength to rip prey into bite size pieces.
As they get older the chicks down feathers are replaced by adult feathers and they begin to more closely resemble great horned owls and look less like Ewoks. As they get larger and take up more room in the nest mom spends more time away from home, often stopping by only for meals. At 6 to 7 weeks the young owls get antsy and begin to leave the nest to climb and explore neighboring branches. At this point they are referred to as branchers, however they still will not be able to fly for a few more weeks, at about 9 to 10 weeks. Once they are able to fly the adults will continue to feed them for a few more weeks while they learn to hunt on their own. Once they have been weaned off of relying on mom and dad for food the young owls will continue to stay around the nesting territory for the remainder of the summer then come fall they will set off on their own.
All of these pictures were taken at a nest in Lakeville, MN this year. I first photographed the female on the nest on January 31st. While she was on the nest I was frequently able to find the male, who is featured in the second, third and fourth pics, in the woods nearby. The first picture of the chicks was taken on March 28th. They were probably born near the beginning of March but since the nest is fairly deep they could not be seen until they got a little bigger. The last three pics were taken on April 23rd. You can see that much of their down is gone. If they are not already branching, they did not on my last visit, then they will be soon. You can tell that one of the chicks looks a little bit larger and more developed. This chick is more likely the older of the two.