Juvenile Great Horned Owls Fledged & Flying
At about six weeks of age, young Great Horned Owls fledge, moving from their nest into nearby trees where they spend their time hiding among the branches while waiting for their parents to deliver food. (If discovered by crows, they are easy to find — just follow the cacophony created by the mobbing crows.) At seven weeks they are taking short flights, but remain close to their nest. At this point they are about 3/4’s grown and resemble the adults except for lacking the prominent feather tufts or “horns.” Even at nine or ten weeks, when capable of extended flight, juveniles tend to stay close to their parents. The adults bring their young occasional food items as late as September, when dispersal begins. (Photo: fledged juvenile Great Horned Owl after a downpour; thanks to Sharon Glezen and Cara Calvelli for photo opportunity)
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Great Horned Owls Raising Their Families
Roughly two months ago the courtship calls of Great Horned Owls could be heard throughout the U.S. as their breeding season began. Mating took place, eggs were laid and incubated for about a month, and several weeks ago those eggs hatched. Looking like balls of tan fluff, the downy chicks can now be seen with their mother in attendance.
Great Horned Owl chick appetites are voracious. At the ripe old age of two weeks they are capable of swallowing a mouse whole. The chicks weigh about an ounce when they are born, and for the first month or so, they gain roughly that much every day. In another month they’ll be taking short flights, but will remain with their parents throughout most of the summer.
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Great Horned Owls Courting & Mating
Great Horned Owls are one of the earliest species of birds to breed in the Northeast. Their intense hooting begins in late December or early January, about a month before actual mating takes place. Males call during most seasons of the year, but the period when the males are hooting vigorously lasts for a month or six weeks. During the mating season the deep, rich tones of the males are occasionally interspersed with the higher and huskier notes of the females. The answering calls of the females are typically heard for only a week or two, toward the end of the six-week period.
Eventually, when a male and female approach each other, they do a sort of courtship “dance.” The male cocks his tail, swells his white bib (see photo), and with much bobbing and jerking utters a series of deep sonorous calls that elicit calling responses by the female. He cautiously approaches the female, continuing much tail-bobbing and posturing. The owls nod, bow, and spread their wings as well as shake their heads. Courting pairs have been observed engaging in high-pitched giggling, screaming, and bill-snapping. Mutual bill rubbing and preening also occurs. Copulation concludes the courtship ritual, with both owls hooting at a rate of 4 or 5 hoots per second throughout copulation, which lasts 4 – 7 seconds.
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Great Horned Owl Nestlings About To Fledge
Great Horned Owls do not build their own nests, though they may provide some lining to an existing cavity or nest. Snags, cliffs and man-made structures provide nesting sites, but most commonly Great Horned Owls use the tree nests of other species such as hawks (especially Red-tailed) crows, ravens and squirrels. Most, but not all, nests are used for only one season. Pictured is a Great Blue Heron nest that has been usurped by a Great Horned Owl family – a feat achieved by the owls claiming the nest as early as February, prior to the return of herons.
After incubating her eggs for roughly a month, the female Great Horned Owl then broods her young for two to three weeks. The father’s role consists of bringing food to the female while she is incubating and brooding. She then tears the food up into bite-size pieces for the nestlings.
When the nestlings no longer need the heat their mother’s body provides, brooding ends but the mother stays with her nestlings until they fledge at about seven weeks of age. (Pictured: Great Horned Owl mother and two downy nestlings, roughly six weeks old. Thanks to Marc Beerman for photo op.)
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A True Mystery Photo
A discovery recently brought to my attention has stumped this naturalist. What you are looking at is a collection of Flying Squirrel tails lying within a 30-square-foot patch of ground adjacent to a stand of Eastern Hemlocks. For several days in succession, additional tails appeared each morning, eventually totaling 20 or more.
Flying Squirrels, both Northern and Southern, are part of many animals’ diet. Among the documented predators are Great Horned Owls, Barred Owls, Screech Owls, Northern Goshawks, Red-tailed Hawks, Martens, River Otters, Weasels, Fishers, Red Foxes and Bobcat. Many of these animals can gain access to the trees where the Flying Squirrels reside. Others take advantage of squirrels foraging on the ground.
The puzzling part of this mystery is the large number of tails. In cold weather (usually in winter, but we’ve had below-freezing nights recently), Flying Squirrels huddle together in tree cavities in an attempt to provide themselves with added warmth. Did a foraging Fisher discover a communal den? How did it manage to capture so many squirrels? Did the survivors remain in the same cavity, only to be captured in subsequent nights? So many questions that this naturalist cannot answer. Perhaps a reader can! (Thanks to John Quimby and Michael O’Donnell, who kindly shared their fascinating discovery with me.)
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Great Horned Owls & Striped Skunks
Striped Skunks do have predators other than Great Horned Owls (bobcats, foxes and coyotes-fishers have been known to prey on skunks, but very infrequently), but these predators have to be pretty desperate before they will prey on a skunk. Automobiles and disease kill more skunks than all of their predators put together, but Great Horned Owls have the distinction of being the primary predator of Striped Skunks.
Being a nocturnal hunter, a Great Horned Owl necessarily consumes prey which are nocturnal. Striped Skunks are active at night and are consumed by Great Horned Owls with regularity, even though a skunk can weigh up to three times as much as a Great Horned Owl (average GHO weighs a little over 3 pounds) and has a potent way of defending itself.
For many years scientists assumed that birds had a poor sense of smell because the area of a bird’s brain involved in smell is relatively small compared with the area found in mammals. However, recent research reveals that birds have a high number of active genes that are associated with smell, and many species may have an excellent sense of smell. It’s fairly safe to assume, however, from its consumption of skunks, that the Great Horned Owl’s sense of smell is not very well developed. In addition, if a skunk sprays, much of the odor is absorbed by the Great Horned Owl’s leg feathers, which extend down to its talons.
A favorite memory of mine is walking through a field at dusk and suddenly noticing a strong skunk-like smell coming from above, not below, me. A Great Horned Owl silently flew overhead, with only the tell-tale smell of a recently-captured skunk announcing its presence.
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Porcupine Preyed Upon By Coyotes
Coyote tracks from several directions coalesced in a spot where the frozen skin of a porcupine lay. There was not one morsel of flesh, and next to no bone, left inside the skin, which had partially been turned inside out. Inspection of the porcupine’s head confirmed the likelihood that coyotes were responsible, as fishers, notable porcupine predators, kill their prey by repeatedly attacking a porcupine’s head, and the head of this porcupine was unscathed (see insert). The only other possible predators would be a bobcat or a great horned owl, and there were no signs of either present. While it is possible that the porcupine died a natural death and opportunistic coyotes took advantage of an easy meal, it appeared to be in good condition, and thus it is equally or more likely that coyotes succeeded in gaining access to the porcupine’s vulnerable, quill-less belly, and successfully attacked and ate it.
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Great Horned Owl Fledglings Still Being Fed By Parents
Great Horned Owls are one of the earliest nesting birds — you can find them on nests in January, February and March, even in northern New England. Eggs are incubated for about a month, typically in March or April with young usually hatching in May or June. The nestlings remain in the nest for six or seven weeks before fledging. Unable to fly until they are ten or twelve weeks old, the fledglings follow their parents around and continue to be fed and cared for by their parents until fall. In late summer, when they have fledged but are still begging their parents for food, you can hear their distinctive calls. To know what to listen for, go to http://langelliott.com/mary-holland/great-horned_owl.mp3 (Sound recording © Lang Elliott – langelliott.com & miracleofnature.org.)
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Great Horned Owlets Soon To Fledge
Great Horned Owls are said to have a wider range of nest sites than any other bird in the Americas. Most commonly they use tree nests of other species, particularly Red-tailed Hawks as well as other hawks, crows, ravens, herons (Great Blue Heron nest pictured), and squirrels.
These month-old young owls have grown rapidly, from a weight of roughly an ounce at birth to about two pounds. They will weigh approximately 2 1/2 pounds when they fledge. By six weeks of age, young Great Horned Owls are climbing out of the nest and perching on nearby branches, and by seven weeks they are taking short flights.
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Great Horned Owls Incubating Eggs
Great Horned Owls are said to have the widest range of nest sites of any bird in North or South America. Like other owls and falcons, this raptor does not build its own nest, but rather relies heavily on abandoned stick nests of diurnal birds of prey. Red-tailed Hawk nests are often usurped, as well as those of Bald Eagles, crows, ravens and herons. Nests may be lined with shreds of bark, leaves, downy feathers from the owl’s breast, fur of prey and trampled pellets. In addition to bird nests, Great Horned Owls also raise their one to four nestlings (usually two) in tree cavities and snags, on cliffs, in deserted buildings, in squirrel nests and even on the ground.
The female Great Horned Owl does all the incubating; the male delivers prey to her at intervals throughout the night. These early nesters have incubated eggs successfully when outside temperatures have been as low as -27°F. Hopefully warmer temperatures will welcome the newly hatched owlets in about a month. (photo: mostly hidden Great Horned Owl in Great Blue Heron nest)
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Mystery Snow Story: Great Horned Owl Preys on Black Guillemot
Let me first say that the scenario I describe is conjecture, albeit conjecture based on the evidence posted yesterday. Today’s post may well tell you more about my train of thought when interpreting signs in the snow than the actual events that took place! The tracks were discovered and photographed by Sally Grassi of Camden, Maine, who saw a large bird (I thought that telling you this would be giving away too much!) devouring something while perched on the snow at night. The tracks that may appear to some as leading to and from the kill site are marks made by something that came out of the sky – they come from and lead to nowhere. I apologize if they were misleading. Given the myriad of ways this scene could be interpreted, the guesses made were strikingly on the mark. Kudos to Kathie Fiveash, who correctly guessed the prey species.
Plot: A bird of prey attacked another bird and proceeded to consume most of it.
Characters: As to the species of predator, the fact that this activity took place at night points to an owl, and the size of the bird eaten (deduced from the size of its remaining foot and bones) narrows the attacking bird down to most likely being a Barred Owl or a Great Horned Owl, both of which are found along the coast of Maine in the winter. (Snowy Owls are diurnal and therefore, even though there are individuals that have irrupted into New England this winter, the likelihood of it being a Snowy Owl is minimal.) Although we can’t know for sure which species of owl it was, chances are great that it was a Great Horned Owl, as they routinely eat large prey, and Barred Owls only occasionally feed on birds this size.
As to the identity of the prey — the geographic location, the time of year, the few remaining feathers and the color of the remnant (unwebbed) foot and leg appear to eliminate all but the Black Guillemot. Although totally black with white wing patches during the breeding season, this alcid (member of the family of birds that includes puffins, murres and auks) has a mostly grey/white plumage in the winter, and brilliant orange-red legs and feet year round. It can be found throughout the year along the coast of New England where it hunts for fish, crustaceans and invertebrates in shallow water near shore. (Thanks to Sally Grassi for Mystery Photos, to George Clark for confirming prey I.D. and J.J.Audubon for the Black Guillemot illustration.)
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Great Horned Owls Courting
The intense hooting of Great Horned Owls begins in late December or early January, about a month before actual mating takes place. Males call during most seasons of the year, but the period when the males are hooting vigorously lasts for a month or six weeks. During the mating season the deep, rich tones of the males are occasionally interspersed with the higher and huskier notes of the females. The answering calls of the females are heard for only a week or two, toward the end of the six-week period.
Eventually, when a male and female approach each other, they do a sort of courtship “dance.” The male cocks his tail, swells his white bib (see photo), and with much bobbing and jerking utters a series of deep sonorous calls that elicit calling responses by the female. He cautiously approaches the female, continuing much tail-bobbing and posturing. The owls nod, bow, and spread their wings as well as shake their heads. Courting pairs have been observed engaging in high-pitched giggling, screaming, and bill-snapping. Mutual bill rubbing and preening also occurs. Copulation concludes the courtship ritual, with both owls hooting at a rate of 4 or 5 hoots per second throughout copulation, which lasts 4 – 7 seconds. (Photo: Great Horned Owl, in captivity)
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Snowshoe Hare Succumbs to Avian Predator
The drama that goes on in our woodlands is never-ending, and winter provides us with a window into life and death scenarios. One of the most sought-after prey animals in northern New England is the snowshoe hare. Bobcats, lynxes, coyotes, foxes and fishers are some of the mammalian predators of this lagomorph. In this particular case, however, the predator had wings (determined by wing imprints in the snow and lack of tracks). While great horned owls do prey on hares, there was a tell-tale sign that it was a hawk, not an owl, which produced this pile of fur and bones. If you look to the upper left of the photograph, and to the upper right, you will see lengthy curved lines of bird droppings, or sprays, that were left by the predator as it plucked its prey. Because it was ejected forcibly, and didn’t just drop down on the snow where the bird was situated, the scat leads one to the conclusion that it was a hawk, not an owl, which deposited it. A woodland accipiter capable of capturing a snowshoe hare after an extensive chase, which this was, is the northern goshawk. (Thanks to Nicole Cormen for photo op.)
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Great Horned Owls Thaw Cached Prey
Great Horned Owls are one of the earliest species of birds to nest in the Northeast –some are already sitting on eggs. Female Great Horned Owls do the lion’s share of incubating the eggs, while the male hunts for and brings her food. While they do eat small rodents, which they swallow whole, the diet of Great Horned Owls also consists of rabbits, hares, opossums, squirrels and skunks, which must be torn into small pieces before being swallowed. Great Horned Owls often kill more than they can eat at one time, and cache the extra food for later consumption, when food is scarce. Needless to say, during winter months the cached prey freezes, and if the prey is large, its consumption is challenging for a bird with a bill that’s designed for shredding and tearing. To solve this dilemma, Great Horned Owls sit on their frozen prey until it thaws, and then proceed to tear it into bite-size pieces.
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Striped Skunk Predators
At first glance, this looks like any other kill site, but if you look closely at the hairs, you’ll see that it was a striped skunk that was preyed upon – a rare find, for two reasons. One is that striped skunks spend most of the winter holed up and only amble out during warm spells (which we had recently). Their mating season is also about to begin. The second reason that this find is unusual is that skunks have very few predators, for obvious reasons. Great horned owls and occasionally a coyote, fox or bobcat will risk being sprayed. In this case, tracks were not evident by the time it was discovered. Initially the lack of anything other than hair suggested that the predator was a mammal which carried off the skunk (great horned owls usually eat at the kill site). However, it turns out that the absence of bones, etc. doesn’t actually rule out an owl. According to the Cornell Lab of Ornithology, occasionally when a great horned owl kills more prey than it can eat, it caches the remains for later use. When in need of food, the owl will incubate frozen prey until it thaws and can be eaten. (Discovery and photo by David Putnam.)
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