Have you ever noticed when you hear a group of crows cawing & making an awful racket in the woods, there’s often an owl at the center of those mobbing birds? It’s a pretty amazing thing to see!
In fact, if you know to listen for these crow mobbing calls, it’s one of the easiest ways to find owls in the woods.
But it also brings up the question of why crows attack them so intensely?
As a general rule, crows attack owls to reduce their risk of predation. Owls do sometimes eat crows and they frequently have overlapping nest habitats which puts them in close proximity.
However, if you watch this behavior for long enough it becomes apparent that crows are expending an incredible amount of energy attacking owls.
It also sometimes seems like they’re putting themselves at risk by coming so close to a dangerous predator, and yet the owls don’t really seem to react all that aggressively.
So what’s really going on here?
- How does crow mobbing work?
- Do crows ever cause harm to the owls?
- Why don’t the owls fight back?
- How often do owls eat crows?
- And aren’t the crows taking a big risk by mobbing them?
There’s a lot to unpack, so let’s explore these questions in more depth…
What Is Mobbing And How Does It Work?
Mobbing is a common defence strategy used by crows and other songbirds to overwhelm and confuse predators like owls, hawks or other dangerous animals.
Mobbing looks like a group of birds all crowding around the danger, calling & even dive-bombing it. If the owl flies away, mobbing crows will often pursue and chase the target in a dramatic aerial battle.
This behavior is surprisingly common & easy to identify with the study of bird language. In the case of crows & owls, mobbing looks (and sounds!) like this:
As for why this anti-predator strategy works, some of the most informative research on this topic was published in an article called effects of avian mobbing on roost use and diet of powerful owls.
This study measured how often various bird species engaged in mobbing owls, compared to how often these same species were predated by those owls.
They discovered some very interesting things:
- Birds who engage in mobbing owls are much less likely to be targeted for predation by those owls.
- Birds that do not engage in mobbing owls are much more likely to be targeted for predation by owls.
So by preemptively mobbing owls, crows reduce their overall risk of predation.
It’s a way of driving predators out of the area before they become a threat (and also has the interesting side-benefit of increasing fitness level in birds doing the mobbing).
Of course this strategy doesn’t come without some risk, so the question still remains of just how dangerous are owls to crows?
Let’s take a look at this next…
Do Owls Eat Crows? (Assessing The Risk of Predation)
It’s well documented that large owls like great horned owls do sometimes eat crows (study), but overall this only makes up a very small part of their diet.
In general, owls are much more likely to eat small mammals like voles, chipmunks, squirrels & even rabbits, with only rare attempts at hunting birds when the opportunity is present.
So then why do crows care so much about owls?
Well, it’s a bit of a chicken and egg situation because given the right opportunity an owl certainly would eat a crow!
However, it’s very likely that part of the reason why crows don’t get eaten more often is because this mobbing, chasing & attacking strategy is such an effective defence.
There’s simply no way of knowing how often owls would hunt crows if they weren’t being pre-emptively attacked.
What we can say for sure is that crows are some of the most social & aggressively territorial birds on the planet.
Crows are particularly skilled at using strength in numbers to overcome the risk of predators like owls. It’s one of the reasons why crows gather in such large groups.
Which Types of Owls Get Attacked By Crows?
In general, large owls like great horned owls, barred owls or great gray owls are the most likely to be attacked and chased by crows. Large owls include species like:
- Great Horned Owls
- Barred Owls
- Great Gray Owls
- Blakiston’s Fish Owls
- Snowy Owls
- Eurasian Eagle Owls
(And by the way… If you observe crows mobbing other types of owls not mentioned here, please let me know in the comments and I’ll add them to the above list!)
On the other hand, small owls are very unlikely to be bothered by crows because they simply don’t pose a big enough threat. Small owls can be incredibly tiny and include species like:
- Pygmy owls
- Saw-whet owls
- Burrowing owls
- Elf owls
Aside from the size of owl, there is one other behavioral trait that likely affects how often they get chased and attacked by crows, and it has to do with their nesting strategy…
Do Owls Steal Nests From Crows?
It’s well known that owls are not very sophisticated nest builders. As a result, it is extremely common for owl species to use old crow nests when looking to raise a family in spring.
In fact, a particular study of 104 pairs of Long-Eared Owls in Idaho noted that every single nest used was original built by corvids (the crow family).
That’s pretty darn conclusive! And it means that not only do owls frequently share an overlapping habitat with crows, but everything down to the exact nest placement and species of trees can be identical.
This is NOT to say that owls steal ACTIVE nests from crows, but rather they will commandeer abandoned nests built in previous years.
An overlapping nesting niche is one of the key predictors of territorial behavior that I covered in a separate article on why birds fight, so definitely read more on that if you’re curious about this.
The basic idea is that anything in close proximity will be more likely to bump against each other, and it’s very likely this contributes to the tendency of crows to attack owls so vigorously.
Of course, most of our exploration has focused on the danger owls pose to crows, however it’s also a worthy idea to explore how much danger the crows pose towards owls!
Will Crows Ever Kill Owls?
As a general rule, crows do not kill owls during these chase, mob and attack events. The primary purpose of mobbing is to intimidate, annoy & generally make life difficult for them.
That said, it is technically possible for a group of crows to do significant damage to owls that could result in death.
In my research for this article I was unable to find any documented instances of crows killing an owl, however there are anecdotal reports that it has happened.
Based on my own personal experience of watching owls being mobbed, I suspect it’s probably more likely that a crow would be injured or killed during the mobbing than the owl.
Certainly in the case of hawks there are rare documented cases of backfired mobbing attempts.
It’s very informative to consider that crows are still willing to take this risk in order to reduce their overall risk of predation from the owl.
Over the years, I’ve spent hundreds of hours watching dozens of different owl mobbing events, and I’ve never witnessed any injuries to either the owl or crows involved, so my instincts tell me this is rare.
So now you know pretty much everything there is about why crows attack owls. I’d love to hear your own crow & owl battle stories!