Owls of Rocky Mountain National Park

Story and photos by Scott Rashid

Six species of owls inhabit Rocky Mountain National Park (RMNP). The largest of these is the roughly 24-inch Great Horned Owl. This flying tiger (as it is often called) can be found in a variety of locations and habitats within the park.

Like the other owls in the Park, the Great Horned Owls do not construct their own nests but rather use an unoccupied platform previously constructed by ravens, crows, Red-tailed Hawks or even Northern Goshawks and Golden Eagles. They will also nest on cliff ledges or witch's brooms.

Great Horned Owlet

Photo by Scott Rashid

Great Horned Owls remain on their territories year-round and their distinctive “who, who, whoohoo, hoo” can be heard virtually any month of the year. The owls heard calling in late summer and fall are most likely that year's young, practicing their call while still on their parent territories. Young owls need to perfect their call before moving out on their own.

Juvenile Great Horned Owls can remain with their parents until the eggs hatch the following year; at which point they become competion to their parents for food and are driven from the territory.

Juvenile Great Horned Owl

Photo by Scott Rashid

Courtship often begins in late December or early January with the male vocalizing for his mate as they recapitulate for another nesting season. Once the pair is together, the male takes the female to his proposed nest site, and will frequently vocalize from it, often with food in his mouth.

If she accepts the nest, she will begin laying her eggs; which are often laid in two-to-three day intervals, but they can be laid up to a week apart. Incubation lasts about 35 days and the young remain in the nest for up to four weeks or more before fledging.

During the first few weeks after the young hatch the male hunts for the family. He brings prey to the nest and gives it to the female, who in turn feeds the young. Once the young are two weeks old and older, the adults frequently drop food at the nest and the owlets feed themselves.

Great Horned Owl

Photo by Scott Rashid

Great Horned Owls have an extremely varied diet. In and around RMNP Great Horned Owls have been documented preying upon rabbits and hares, ground and tree squirrels, voles and mice, snakes, fish and birds from sparrows and warblers, to half-grown turkeys, crows, hawks, other even other owls.

Long-eared owl

The smaller long-eared owl looks similar to its larger cousin, but this owl is 15-inches from head to tail.

Long-eared owlet

Photo by Scott Rashid

These owls begin courtship in February and often begin nesting from mid-March to late-May. The nests that I have monitored have had between two and four owlets per nest.

Their nests are often adjacent to large openings in the forests where they can hunt the meadows and capture their prey. Pairs of long-eared owls often nest in much closer proximity than Great Horned Owls. I have seen them nesting as close as just a few hundred yards apart.

Incubation lasts about 25 days but can take as long as 30 days. Young Long-eared Owls remain on their nests for three weeks before venturing out along the branches near the nest. They are typically independent at about two months post-fledging.

Adult long-eared owl

Long-eared Owls are small mammal specialists preferring to feed upon voles and mice, but have been documented feeding upon meadow voles, northern pocket gophers, deer mice and birds including finches, sparrows, starlings, and occasionally larger birds such as America Robins and Northern Flickers.

Boreal owl

Boreal owl

Photo by Scott Rashid

The Boreal Owl is a species that nests in old growth spruce-fir forests usually above 9000 feet. These owls are the largest of the cavity-nesting species found in the mountains. In RMNP they nest in abandoned Northern Flicker cavities, or other cavities large enough to fit the female.

Male boreal owls seem to defend the nest tree versus a large territory. Male boreal owls give a distinctive “bo, bo,bo,bo,bo,bo,bo,bo” that is often heard from February through April. The call of the owl sounds similar to the structural sound that Wilson's snipes make as they dive during their courtship displays.

This call can be quite loud and is often heard over a large area. However, when a female appears, the male's call becomes much quieter and often more rapid. The female can be heard giving a soft, singlenote “cheet” call.

After the female has accepted the male and the nesting site, she remains in the nest both day and night; only leaving for a few minutes to a end to her personal needs.

The male begins hunting after dark and appears to hunt in the forest exclusively.

Boreal owls in RMNP prefer red-backed voles, but have been documented preying upon deer mice, meadow and montane voles, shrews, northern pocket gophers, and birds including American robins, yellow-rumped warblers, white-crowned sparrows and Cassin's finches.

The owlets remain in the nest for about 30 days and can fledge at any me of the day or night. Once out of the nest they are capable of flight, and are quite hard to find in the dense forest.

Northern Saw-whet owl

The Boreal Owl's smaller cousin, the Northern Sawwhet Owl can be found in a broad array of habitats but seems to prefer those that include ponderosa pines, aspen, Douglas fir, junipers, ground junipers, downed logs, openings in the meadows, and a water source. Male northern saw-whet owls appear to remain on their territories year-round, but the females and juveniles wander a er the end of the nesting season.

At fledging the owlets are dark brown on their chests and backs and yellow-ochre on their bellies. The young remain in this plumage until September, then molt into their adult plumage. That molt takes about a month to complete.

Twin juvenile Northern Saw-Whet owls

Photo by Scott Rashid

Their preferred prey is deer mice, but will also feed upon voles, northern pocket gophers, shrews and birds including pine siskins, red-breasted and pygmy nuthatches, yellow-rumped warblers, Cassin's and house finches, and house wrens, but I am sure they can take many more avian species.

Courtship can begin in January and con nue into July; un l the male recruits a female.

Northern Saw-Whet owl

Photo by Scott Rashid

Northern saw-whet owls fit best in a cavity excavated by northern flickers, but will also nest in nest boxes made to the proper size and having the proper size entrance cavity.

Northern Saw-whet owl

Photo by Scott Rashid

The males call from the cavity entrance when trying to attract a female. Once she accepts the cavity and begins laying eggs; incubation begins. Incubation lasts about 30 days and the eggs hatch in the order they were laid. The owlets remain in the cavity for 30 days or more before fledging. In a natural cavity, northern saw-whets frequently fledge two owlets, but in a larger nest box can produce more than twice that.

Northern pygmy-owl

Northern pygmy-owls are another small cavity-nesting species that can be found within the park. These 7-inch owls are a diurnal species that are most active at dawn and dusk.

Northern pygmy-owl

Photo by Scott Rashid

In many ways they are anatomically unique among the other owls in RMNP. First off, northern pygmy-owls have short, rounded wings and long tails, whereas the rest of the owls in the area have long wings and relatively short tails.

Northern pygmy-owls do not have a silent flight; there is no need for silent flight as they are active during the day. Furthermore, northern pygmy-owls do not see much better after dark than humans do. After all, there is little need to see after dark if you are not active then.

Northern pygmy-owls have feathered eyespots on the backs of heads that look more like eyes than the birds' real eyes do. These eye spots act as a deterrent from birds attacking the owls from behind as the owls perch in the open searching for prey. Northern pygmy-owls can frequently be seen perched in the open when hunting voles in the open meadows.

Northern pygmy-owls prey upon a wide variety of species, including red -backed, meadow and montane voles, least and Colorado chipmunks, deer mice, shrews, and birds including yellow-rumped, MacGillivray's, orange-crowned and Wilson's warblers; chipping, white-crowned and, Lincoln's sparrows; green-tailed and spotted towhees; American robins; house and Cassin's finches; black-headed, pine and evening grosbeaks; black-capped and mountain chickadees; house wrens; and. broad-tailed hummingbirds. They will also occasionally take lizards and insects.

Northern pygmy-owlet

Photo by Scott Rashid

Northern pygmy-owls begin their courtship in mid- February, but often do not begin nesting until late April or early May. They have the longest courtship and largest territory of any small owl in RMNP.

As with the northern saw-whet owls, the northern pygmy-owls preferred habitat is comprised of ponderosa pine, aspen, Douglas-fir, junipers, ground junipers, downed logs, openings in the meadows and a water source.

Male northern pygmy-owls often secure a nesting site as early as February and March. Once a female is attracted to the male by his vocalizing, he will take her to the potential nest site and vocalize from it. He then exits and flies around her and reenters the nest in hopes that she will enter the cavity and find it to her liking. If she decides the cavity is a good one, they will move throughout their territory calling and defending it from other owls. When she feels egg-laying is close-at-hand, she will remain within view of the nest during the day.

Northern pygmy-owl

Photo by Scott Rashid

She will begin laying eggs from late April to mid-May. Owls in RMNP raise between 2 and 4 owlets in a nesting season and the owlets remain in the cavity for about 30 days before fledging. At fledging the owlets are about three-inches from head to tail, as their tails are only a few millimeters in length. The owlets remain with their parent for about 30 days before moving out on their own.

It takes the owls about 30 days for their tails to grow to the full length of about 3 inches.

Flammulated owl

When people see the tiny flammulated owl, one of the first things they notice besides the bird's petite size is its dark eyes. The flammulated owl is one of only four owls in North America that have dark eyes. All the other owls in North America have yellow eyes. The flammulated owl gets its name from the color of the scapular feathers on the birds back. They are rufous or flaming or flammulated.

Male flammulated owls arrive on their nesting grounds in North America in late March and early April. Soon after, the females arrive and courtship begins. In RMNP, flammulated owls can be found in habitat identical to that of the northern pygmy and the northern saw-whet owls. I know this because I had all three species nes ng in RMNP in the same tree in different years.

Flammulated owl

Photo by Scott Rashid

Once on their territories in the spring, these diminutive predators locate a vacant nest cavity and the males will begin giving their distinctive “boo” or “boo, boo” call. Their call sound is similar to the call of the long-eared owl, but the call of this tiny bird is much quieter. The male flammulated owl will frequently be heard giving his hooing, while the female responds with a single raspy meow.

After the male has decided upon a cavity and the female accepts both him and the cavity, she will begin laying her eggs. After the eggs are laid, the male will deliver food to the female in the cavity at a rate of about one moth per minute. This will continue for about three hours after dark. During incubation this activity continues for several nights after the eggs are laid, then again afer the eggs hatch. When the owlets are about two-and-a half weeks old the female will hunt for the family along with the male.

Flammulated owl

Photo by Scott Rashid

Flammulated owls feed upon insects, with their primary prey being moths. They capture their insects in the air and glean others from branches of trees and bushes.

The owlets fledge at about 30 days after hatching and remain with their parents for a few weeks before they migrate south for the winter. Adult owls appear to migrate first, followed by the young of the year.

Artist, researcher, bird rehabilitator, author, and director of a nonprofit are only a few things that describe Scott Rashid. Scott has been painting, illustrating and writing about birds for over 30 years. In 2011, Scott created the Colorado Avian Research and Rehabilitation Institute in Estes Park. In 2019, Scott located and documented the first Boreal Owl nest in the history of Rocky Mountain National Park in Colorado. Scott has written and published five books and several papers on a variety of avian species. More information available on his website.

http://www.carriep.org/