You have heard the expression “wolf in sheep’s clothing”? With the Great Grey Owl, it is more a case of “little owl in big owl clothing.” Though this owl is the largest owl in North America – measuring about 2 feet tall (61 cm) – it weighs only 2-4 pounds (0.9 - 1.8 kg). Compare that with a Eurasian Eagle-owl, which is just slightly larger, but weighs 3-9 pounds (1.4 - 4.0 kg) and you will see what we mean. Why is this so? Great Grey Owls have relatively small bodies but are covered in so many dense layers of long feathers that they appear to be much bulkier than they are. It would be like you wearing all your clothes at once, which would definitely make you look much bigger. One advantage to this could be protective – a large appearance can be deceiving to predators and make them think twice before attacking such large prey.
Soooo, this is a very complex question, but we can look at a few things.
We’ll start with one of the easiest aspects. Part of our fascination with owls is their ability to blend into nature, so many of the photos we get are going to be selected to highlight this thing which is amazing to us. If you go back through all the owl pics here, there are absolutely some, where even when cropped in tightly, are still pretty invisible. Others are fairly distant, and you can still see them well. Especially when moving, camouflage loses much of its effectiveness. That is why owls spend most of their day motionless, just sitting and observing.
Now, does an owl have awareness of its camouflage? Owls have been around for 60 million years. They are almost everywhere in the world and have become successful in almost any ecosystem. If you pick any random owl, you’re most likely going to find a brown or grey as a main color. Even of you didn’t add any patterning, it’s still a very good start to blend in to a backdrop of trees. Over many generations, we’re going to be left with owls who are born with a sense of what works. Blending in with your background is called crypsis, or cryptic camouflage. It’s something done by countless animals. For the owls, even when they don’t blend in perfectly, they are still not very noticeable. They are generally up above their prey, and probably hear most prey before it has a chance to see them. It doesn’t need to be perfectly invisible all the time, just long enough to get it time to get the jump on their target.
These images have them standing out pretty well, but the owls have also been pointed out to us by the photographer, they are still reasonably hidden, and we aren’t a tiny rodent crawling much lower, and we’re examining it with human intelligence. The only thing that will likely give this owl away to the prey is movement when it takes off.
Birds have a bit more intelligence than some other organisms of course, and there is evidence that owls have some sense of self awareness of their camouflage. Owls will contort their body and feathers to elongate and slim down to better mimic a tree branch when they wish to hide. They also seem to know their eyes are noticeable and will shut their eyes to become even more hidden. Here is a pic of Flammy from the other week showing what a difference closed eyes can make.
Owls will get much feedback from their camouflage ability. As a predator, they will learn what works or what doesn’t, and I’m sure by now much of that is in their genes. They also need to stay hidden during the day to avoid attacks by other animals that don’t want them around so they will learn what places they get bothered less.
I’m disappointed I haven’t seen any studies specifically on this, but I will keep my eyes out for any. The things I’ve mentioned seem to be a combination of thoughts that I could find. I did see some neat thing about how some Japanese quails learn if they lay eggs with darker or lighter spots and will then make future nests in lighter or darker locations to help them blend in more, so there are many cool tricks bird have to be invisible. How much is genetic/mimicry/learned still seems to be up for debate, but it is all fascinating.
I’m very happy to hear when I write something that captures someone’s attention, especially if they aren’t really into the subject already.
If you are interested in more, similar content, this post about talons is my most popular, and here is a summary of a famous research paper of acoustic location of prey which was used to establish owls hunt with their ears. The people at !digitalbioacoustics told me the author of the original paper is very famous for his work with whales as well.
Reminds me of the time late at night when I saw an owl fly overhead and was amazed at what nothing sounded like. No flaps, no rustling, no noise whatsoever. It was freakishly silent - as you would expect for a predator.
They have some really great adaptations. They have longer wings than the average bird, requiring less flapping. I likened this before to a larger cooling fan being able to run at a lower RPM to provide the same CFM, making the fan quieter, which seemed to explain it well to a tech crowd like we have here.
Their feathers are also much less dense and more flexible than other birds, and the trailing edges are fringed to break up the major turbulence to kill sound. Getting to handle owl feathers is one of the most informative things I’ve experienced in my amateur owl research. If you’ve never had the chance, I encourage any owl fans to go to a local program where you can learn about owl. They will usually pass around bones and feathers or wings and you can really learn a lot by touch.
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