Ask Us Anything: Great Horned Owl Live Cam

2022 season

Have a question about Great Horned Owls, or something you saw on the Explore.org Great Horned Owl Live Cam?

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Ask Us Anything: Great Horned Owls

Once a week, we'll go through submitted questions and post answers on the cam chat board, so check back for answers! We'll also post them here so we can all learn together about these amazing birds!

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Owl Characteristics

Question: How do they turn their heads all the way around? How are they able to move their necks anywhere they want?

Answer:

Owls are able to move their heads about 270 degrees- which is almost all the way around, but not quite- more like 3/4ths. They can do this because they have extra neck bones and strong neck muscles. They also have special circulatory adaptations so they don’t cut off blood flow when they turn their head so far. They have 14 neck bones, compared to the 7 in humans.

Being able to turn their heads so far lets them see behind them without moving their torso or the rest of their body, which helps reduce the amount of sound they make—which helps them stay unnoticed and hidden from any potential prey or from any birds that might want to mob them.

Diet and Feeding

Question: What do they eat?

Answer:

Great Horned Owls eat all sorts of things, including (but not limited to): small mammals (like voles, mice, and squirrels), larger mammals, like rabbits or skunks, birds like songbirds, gulls, herons, ducks, or pheasants, reptiles, amphibians, fish, and insects. They do seem to eat more mammals than anything else, followed by birds. It varies based on what prey is around, and that they can catch.

Question: How do Great Horned Owls not choke when swallowing large prey?

Answer:

The trachea is separate from the esophagus, so the food goes down the esophagus into the proventriculus, where digestion starts. The esophagus can expand quite a bit, and muscle contractions force the prey down. The trachea is a small opening behind the tongue where the owl breathes. It is surrounded by the glottis, which is the entrance to the trachea. The glottis reflexively closes when touched, which prevents food from going into the lungs. The esophagus is much larger than the small tracheal opening. As well, owls can breathe through their nares (nostrils on their bills). For more information:

• Digestion in Owls on The Owl Pages

• The Specialization and Perfection of Falcon, Owl, and Vulture Beaks – Bird Beaks Part 3-- scroll down a bit to get to the owls

Great Horned Owl Behavior

Question: I had heard that owls need to be in a dark place during the day to sleep. If so, why is their nest so open and out in the daylight?

Answer:

Since Great Horned Owls don't build their own nests, they're limited to where old magpie or hawk nests are located-- hence, this more open location. They do prefer that their nests have good access, so they can easily fly in and out and are able to see any potential predators that might try to climb up into the nest.

Not all owls are strictly nocturnal- there are a few species which are crepuscular, or most active at dawn and dusk. Great Horned Owls do tend to be more nocturnal. However, since the owls have chicks, they're going to be active more often during daylight hours as they have all those hungry mouths to feed.

Even when they don't have chicks (like during the winter, and later in the fall when the chicks are full grown) when they roost during the day they probably aren't in complete darkness. Though I'm sure they'd love to have a nice dark barn or outbuilding to roost in during the day, most will be tucked up against a tree, camouflaged against the trunk or hidden in the branches. Even if they are roosting tucked up in a dense pine tree, it won't be completely dark during the day, though it certainly will be shaded.

Question: Why are the owls awake? Shouldn’t they be sleeping during the daytime?

Answer:

Great Horned Owls are crepuscular, which means that they are most active at dawn and dusk, and also nocturnal, which means they are awake and active at night. However, this depends on both their food supply and the weather. If it’s overcast and cold, they may hunt earlier in the day. As well, when the adults have fast-growing hungry chicks to feed (like they do here), they will hunt throughout the day to feed their demanding chicks.

Question: What do the Great Horned Owls do all day? Why don’t they seem to be moving a lot?

Answer:

Because Great Horned Owls are crepuscular (active at dawn and dusk), and also nocturnal (active at night), during the day they sleep—what we call ‘roosting.’ The Great Horned Owls on the cam usually roost in trees or in the thick brush. The male of this pair often roosts directly under the nest, in the same tree.

Question: Where is the male owl?

Answer:

Mr. Hootie (as the male owl has been affectionately named by cam viewers) is usually roosting (which means perched, and sleeping) directly below the nest. The cam is zoomed in so we can see the female (her name is Wonky) and their chicks in the nest, so we can’t always see him on the cam. But, if you listen carefully, you can often hear him hooting in the distance as he chats with Wonky and their chicks! When he’s not roosting near the nest, he’s off hunting for his hungry growing chicks.

Great Horned Owls- ORI's neighbors

Question: Could the Great Horned Owl pair by the ORI office who have been nesting there for a while (called Hunter and Tabitha) be offspring of Hootie and Wonky (the pair currently on the live cam)? If yes, would this make Hooty and Wonky more tolerable towards them?

Answer:

This is all speculation since we haven’t banded or closely watched these owls, but this is unlikely. The juvenile owls usually disperse (or move out of the area) by winter and will often go many miles away. After they leave their natal ground (the area where they were born) they will wander (or “float”) for a few years until they find a mate and an open territory. If there was an open territory close to where they were born they might take it. Males usually take a few years to find a mate and an open territory of their own.

Question: Would Hunter and Tabitha ever nest in Wonky and Mr. Hootie’s nesting areas, and vice-versa? Do the two Great Horned Owl families ever share hunting areas?

Answer:

Great Horned Owls are VERY territorial, so they would never nest in an adjacent pair’s territory. This is why there is so much hooting in the winter, as the pairs are letting everyone in the area know where their territory is an that it is very much occupied.

Question: Is it possible for the juveniles from each Great Horned Owl family to hang out in the other family’s territory? Could one of Hunter and Tabitha’s juveniles hang out on the Charlo Osprey perch (which is in Wonky and Mr. Hootie’s territory)?

Answer:

It is possible that one of Hunter and Tabitha’s young could try to hang out on the perch, but it would probably be chased off very quickly. Great Horned Owls are very territorial, and will even chase off their own juveniles from previous years by the winter.

Great Horned Owl Vocalizations

Questions:

Do male Great Horned Owls hoot 4 to 6 times (with 5 being most common), and females 7 to 11 times (with 7 being most common)?

Are there regional or generational differences in the number of hoots males and females give? Does what they hear when they’re young make a difference in what they sound like as adults?

Answer:

Number of hoots

According to Birds of the World, the number of hoots (or syllables) varies in a population and among individuals. However, each male Great Horned Owl has a unique sound and pattern, a ‘vocal fingerprint,’ and you can use spectrograms (also called sonograms, which are visual representations of sounds) to identify an individual. [for more information about using spectrograms to ID birds, check out Nathan Pieplow’s Earbirding website].

Male and female Great Horned Owls will duet, or hoot together in a call-and-response type way, or sometimes slightly overlapping each other, as a way to let the neighborhood know that this is their territory (called ‘territorial advertisement’ in research papers). These duets can be anywhere from 10 to 60 minutes long. The female’s part usually goes like this: 7 hoots (sometimes 6), that last about 3 seconds total. The male’s part is usually a 5 hoot sequence, also lasting about 3 seconds. Duetting usually starts about one to two months before the first egg is laid.

Young males (juveniles, or birds that hatched that year) will mimic adult hoots during their first winter, but female Great Horned Owls don’t seem to do the same- they’ll just start giving full female hoots during their first spring.

Other interesting facts about vocalizations:

Female Great Horned Owl vocalizations are higher in pitch because they have a smaller syrinx, which is the vocal organ in birds. [For more information, see the Wikipedia page for ‘Syrinx (bird anatomy)].

Great Horned Owl chicks begin to vocalize inside the egg a few hours before hatching, probably to attract the attention of the female and let her know they’re on their way out!

Eggs and Incubation

Question: Do Great Horned Owl eggs develop the same as eagle eggs and other bird eggs?

Answer:

Yep, they do!

Here is a video on YouTube from Illustra Media’s documentary about birds that explains the process-

FLIGHT: The Genius of Birds- Embryonic development

And, I found this cool video from NPR’s Skunk Bear series that explains how the developing chicks breathe:

How Birds Get Oxygen Inside their Eggs

Question: Do Great Horned Owls lay eggs right up until they die? Are the eggs of an older female just as viable as the eggs of a younger one?

Answer:

There isn’t any data on this, so we don’t know. In other species, it has been noted that there is an increase in productivity (the number of young they have) in the first few years of breeding, and then a high productivity when they are fully mature, followed by a decrease as they age. But, we are not aware of any studies that have looked at this with Great Horned Owls, so we don’t know if this is true for them too.

Great Horned owls live for a long time—the record for a wild banded bird is 28 years. Whether or not the eggs are less viable with age has not been studied, and would be very difficulty to study because the age of wild birds can be very difficult to impossible to determine unless you are able to band them as chicks. When researchers catch wild birds, many times they are only able to age them as ‘HY’ birds (Hatch Year birds), or ‘AHY’ (After Hatch Year)—so, you can tell if a bird is a juvenile, or an adult, but once it has adult plumage it’s often very hard to tell precisely how old it is. If you have the bird in hand you can sometimes study molt patterns that can help give you a slight more narrow age range (After Second Year, After Third Year, etc.) but most older birds won’t have substantial differences in plumage or molt, so it can be impossible to tell.

Of course, for a bird that’s been viewed on a live cam for many years, you may get to know the individual bird and you could potentially see that fewer eggs hatch over the years, or that she lays fewer eggs. However, there are many other factors involved in reproductive success other than age, so you would need to have multiple nests with years of data before you could make any significant conclusions around age. In the wild, senescence (the process of growing old, where cells stop dividing but doesn’t die—aka biological aging) is rarely observed, as most birds die before they become elderly.

Question: The window for a Great Horned Owl to incubate their eggs is between 28 to 37 days. If an egg is not viable after 37 days, what might have happened to the egg to make that happen? Why is there a 37 day limit, and could it ever go past 37 days?

Answer:

Incubation requires a temperature of approximately 98 to 100 degreed F, which is provided by the female’s brood patch (a giant blister-like bare spot on her stomach, which she uses to transfer heat from her body directly to her eggs. For a bit more info on brood patches, see this past ORI blog post: “See the patch of bare skin? It’s a brood patch”

During the time the female is incubating the eggs, the embryo develops within the egg. This takes about 30 days for most owl species, give or take a few days. Incubation is followed by brooding, which is when the female still applies her brood patch to the chicks, but not as tightly.

If there is an egg that takes much longer than the others to hatch, during brooding it would likely not be getting quite enough heat, and as the other chicks age even less pressure (heat) would be able to be applied to the entire clutch/brood.

Once the female detects hatched chicks, she begins to transition her behavior away from incubation and towards parental care. With larger clutches of asynchronously hatching chicks (which means the chicks hatch on different days), it can take a while for all of the eggs to hatch. Eventually, the female will stop incubating any unhatched eggs, and may even push them out of the nest. Most of the non-viable eggs likely were not fertilized, or did not develop properly, or possibly were either over or under-incubated (too hot or too cold for a period).

Question: Is the first chick that hatches always a female, or usually a female? If not, why do some insist on saying otherwise?

Answer:

Beth says she would be interested to know who is saying this 😊

This relates to what biologists call ‘facultative sex ratio manipulation,’ or sex allocation theory. “Sex allocation theory predicts that females should bias the production of offspring towards the sex that will maximize maternal fitness.” (Nicole Taylor, Chapter 2: Burrowing Owl Offspring Sex Rations: a Test of the Trivers and Willard Hypothesis).

From Beth: “I can imagine that if the first chick were female, then it would be bigger (females are the larger sex in owls), and because of that might have a better chance at survival and outcompeting its younger, possibly smaller male siblings. This could be an advantage in a low prey year so that the older one survives while the younger, smaller ones perish due to there not being enough food for them all.

However, to decrease competition, the first chicks being male (and therefore smaller) and the later chicks being female (and larger) would make more sense. This would give the male chicks a few extra days to get larger, so all chicks would have a more equal chance of surviving.

In Boreal Owls, it has been hypothesized that the female is able to manipulate the sex ratio of her brood based on the prey availability that year, with the broods being female-biased in a low prey year and male-biased in a high prey year. This does provide some evidence to support the theory that Boreal Owls are investing more in females in a low prey year, because females have less variable reproductive success, which means that a female is more likely to produce a consistent number of offspring every year. Males have a more variable reproductive success, as they are more likely to produce either a ton of offspring, or none. Therefore, having more male chicks is more risky (in terms of contributing to the overall Boreal Owl gene pool), but in a high prey year there is more room for risk, and the potential of producing males with very high reproductive success over their lifetime. It is also possible that the females are more likely to survive in the nest since they have a larger body mass, and therefore it would be beneficial for the first hatchling to be a female.”

Question: How does the female Great Horned Owl keep her talons away from her eggs and chicks while she's incubating and brooding?

Answer:

While the female is brooding, she places her brood patch-- a bare area of skin without feathers on her abdomen-- over/on her chicks. The skin-to-chick (or skin-to-egg) contact keeps the chicks warm. For more about brood patches, see:

• Brood Patch - Wikipedia

• Brood Patch- Owl Glossary- International Owl Center

• 'See the patch of bare skin? It's a brood patch' - ORI blog post from 2018

When the female owl stands up, she will not step on her eggs or chicks. She uses her bill to rotate and tend the eggs, tucking them just right so they stay warm. While incubating, the female owl is effectively laying on her belly, and her feet and talons are back behind her. Male owls don't develop brood patches, and so the females are the ones that do all of the incubating and brooding.

After the eggs hatch

Question: What are the weekly/biweekly growth development stages of the chicks?

Answer:

From Beth- “Watch the camera to find out…take detailed notes and photos…and let us know 😉”

Here’s a neat resource from the International Owl Center, which includes photos of three captive-reared broods at their center in Minnesota: Great Horned Owl Age Chart

And, as always, Cornell Lab of Ornithology has excellent info as well- see the question, “In General, What Can I Expect to See As The Nestlings Grow?”

Question: We know that after a few weeks Great Horned Owl chicks can regulate their body temperatures on their own, so what is making this happen other than the downy feathers? Also, if a nest has only one owlet in it (like a few shown on other cams this season), are those owlets just as warm as the ones cuddling each other, or are they actually more in danger of getting cold?

Answer:

For young chicks (and eggs), the female owl incubating or brooding is the main source of maintaining the young’s body heat. They are born with a thing coat of natal down, and at around 2 weeks of age they grow in a heavier set of down feathers, called mesoptile down. Even with this second set of downy feathers, it can be dangerous if the chicks are exposed to periods of temperatures below 60 degrees Fahrenheit.

As they get bigger they are better at thermoregulating for a few reasons. Increased size means less surface area for heat loss. They are also better able to convert food into energy, which also helps with thermoregulation. By the time they are 25 days old, their thermoregulation capabilities are at about 90% that of an adult, and by the time they leave the nest at 6 to 7 weeks old they are able to thermoregulate almost completely on their own.

In terms of not having siblings to cuddle with, a single chick could potentially be at higher risk of being cold when left completely alone, but most likely the advantages of having two parents giving their undivided attention would make up for that. Not having to compete for food with siblings would lead to faster growth.

Question: Have you ever heard of a Great Horned owl male shredding prey and feeding the chicks? There is a Great Horned Owl cam in Ennis, Texas, where they say the male has fed the chicks twice while the female was off the nest.

Answer:

That doesn’t sound completely unusual. Male Great Horned Owls will sometimes attempt to feed chicks, but when the female is around she always seems to take over.

Question: When the female Great Horned Owl starts to hunt after the chicks can thermoregulate on their own, does she only hunt close to the nest? If prey starts to become sparse, will both parents go further away from the nest?

Answer:

The female Great Horned Owl will only hunt if the food provided by the male isn’t enough. She may hunt opportunistically near the nest—for example, if she happens to see a mouse she’ll grab it. In general, the female will only go as far as she needs to get food, and the chicks will be more vulnerable while she’s gone. Once they are older they are a little safer to leave for longer periods of time.

I can’t find specific details, but there are 3 records of a single parent successfully raising chicks after the other mate died or disappeared, including one record of a nest where the male died and the female was able to successfully raise her chicks alone.

The parents will go as far as needed to hunt for their chicks. In a low prey year this can mean further distances, which will leave the chicks alone and potentially unprotected for longer periods of time. However, if prey availability was so low the parents had to travel far outside of their territory to hunt, the likelihood of the chicks surviving isn’t very high. Owls are generally pretty good at gauging if there will be enough prey for them to raise a family, and if food is low they may not breed at all.

Question: The owlets and female Great Horned Owl will be laying right on top of dead prey, which can sometimes be in the nest for more than a day. How do they not get any diseases from the dead prey?

Answer:

A cache (or stash) of prey in the nest is not a hazard for the chicks or adults. Owls often cache extra prey in the nest, and it gets eaten up pretty quick. In some owl species, like Snowy Owls, if there is abundant prey they will pile up more lemmings than can be eaten around the nest, but usually the cached prey will get eaten within a few days. Sometimes excessive parasites in the nest can cause disease or health issues that impact survival, but this is not too common and owls tend to keep their nests fairly clean. Old forgotten and uneaten prey or parts will dry out and desiccate.

A detailed post by Mark H. X. Glenshaw about caching behavior observed in Great Horned Owls in Missouri: "Will that be cache or...?"

Cam location

Question: Where is the owl nest located?

Answer:

This Great Horned Owl nest is located on private property near Charlo, Montana. Charlo is on the Flathead Indian Reservation, in the Mission Valley in Northwest Montana.

Question: How did they know where to set up the cam?

Answer:

We followed the owls! Last year they nested a little distance away, in an old hawk nest in a tree next to a pond. This year, they decided on this new location. We never know which spot they will pick, so early in the breeding season while they’re still deciding they will spend lots of time hooting and defending their territory near various nesting locations, so we know which spots they’re considering, and can watch them to see which nest they end up picking.