Crowing about Crows: An exploration of crows' craftiness

I was out in the garden last week, doing my favorite thing - wandering about slightly aimlessly. As I ambled I did little jobs as the mood struck me: picking up fallen twigs, throwing a ball for the dogs, tying in a wayward branch. It was one of those still autumn afternoons when all sensory inputs feel diluted - yet still sharp. It was quiet, save for an occasional bird call and the crackling of leaves under our feet The smells of autumn were faint but poignant. The light was weak but crystal clear. It was cold but not chilled. Everything felt as it should be and there was nothing, and everything, magical about feeling a part of the cycle of life. As I scanned upward into the grayish blue wash from the December sun, I saw a veritable river of crows flying with distinct synchronicity and apparent purpose. All in the same direction, all along the same path. As time passed, the stream of corvids continued. One might say relentlessly. Could anyone who noticed the torrent of crows have escaped the pull of that moment? Not I.

I started to count. A group of 25 crows, four groups of 25. Ten groups of 100. At any one time there were more than a 1000 crows in view. “How long would this river flow?” I wondered. It was at least 5 minutes, probably closer to 10. And to continue the river analogy, I myself was being swept downstream into a fascination with the lives of crows. Little did I know, I was pretty late to the party, but I reckon the other crow enthusiasts will not begrudge me.

Let’s start with this river I saw. A quick google search told me that the river of crows I saw were flying directly toward one of the biggest crow roosts in Maryland - to the site of the old White Flint mall in Rockville. Estimates put that crow roost between 1/4 and 1/2 of a million crows, though these estimates are some 25 years ago. That’s a lot of crows, and a lot of crow droppings! While crows spend their winter days in small groupings of a dozen or so, which turn out to be tight family units, they come together in the thousands at night time. They probably do this for warmth and mutual protection. The later because crows don’t see well at night while many of their predators do. So, luckily for their survival in an ever more built environment, crows quite like to roost in lite up urban areas. In addition to gaining warmth and protection, the crows also exchange information about food sources as they roost. Scientists have documented an increase in the number of crows who feed off a given carcass night on night for crows that roost near one another. And, the winter roost festival is undoubtedly a good time to find a mate, for most of the time crows are quite territorial and stay within their family’s fiefdom.

Finding a mate is surely a big moment in a young crow’s life. They typically mate when they are two years old and they mate for life - raising their family and doing most everything together. Unlike most birds, crow parents never chase off their offspring. And while some offspring will go off to find a mate of their own, many stay with mom and dad and help feed the pregnant crow and their young siblings. Older siblings also help defend the nest and one another. Within the family unit, each crow has a unique call it sounds upon reuniting with their family, as if to announce, “Hey I’m home”. As chance would have it, I saw a couple of crows settling into a tree outside my window as I wrote these lines. I was alerted to their presence when I heard them cackling, quite a different sound from the the classic “caw” I’d always associated with crows. When I heard these calls and looked up, a couple of other crows were just joining the pair in the tree. They all seemed to rustle up a hello and then settle down to enjoy a spot of sunshine. A little bit later a few more joined and there was another burst of hellos, followed by more sunbathing. This went on until there were about 15 crows in the tree, a common number for a crow family unit. Interestingly, one study found that if a male breaks off and finds a new mate, he and his family may well retain friendly intercourse with his birth family. Daughters who go off and mate rarely do so - perhaps because male crows are dominate and her new partner won’t tolerate other males around. When crows are in the larger community they have a different call to identify themselves from the one used within the family. The public call is louder and seems to announces “Yo! Here I am.”

While they are with their parents, young crows appear to be learning all the time. One study showed that nestlings learned to avoid particular humans who had frightened their parents. Another study explored tool use (Acherman, The Genius of Birds). The New Caledonia crow makes a tool out of a leaf with a small hook at the end that they use to fish out grubs. At two months old a young crow will start trying to use his mother’s tool. At 5 months she can make a rough tool, but often uses the wrong part of the leaf - without the essential barbs of the pandanus leaf that make the hook. By eight months, she can make the tool properly about half the time but still can’t manipulate it dexterously enough to fish out very many grubs. It is not until the crows are 18 months old that they are effective at grub fishing. Meanwhile, her parents and siblings share their grubs with her. Both these instances of passed on knowledge, tool making and threat recognition, open up the idea that crows have a culture that is passed down between generations. Another example of crow culture are crow funerals. When a dead crow is found, crows will gather in a nearby tree. Usually, crows that gather are busy vocalizing “Yo! Here I am.” or making other cackling sounds which we don’t understand. But in the event of gathering near a dead crow, the group is silent, for a time. Then they erupt in a chorus of shrill calls. The gathering repeats the silent, chorus of calls patterns for 10 or 15 minutes and then fly off almost as if on cue. Humans who have witness such unusual events describe it as eerie or moving.

And a short note on crow vocalizations. In addition to the their two names, crows have calls for specific threats - owl, human, hawk. Their vocalizations are far more varied than the ‘caw’ we all know. They cackle, rattle, click, coo and even clack their bills. Even the caw is varied in pitch and length. Crows also mimic other birds and even human voices. Here’s a video of a crow saying “How are you?” But I have to warn you, I’ve heard that watching youtube videos of crows vocalizing can absorb a great deal of time. To wit, here’s one of a crow snowboarding.

So now we have crows that, for all intents and purposes, have names, language, dedicated family units and some level of cultural development. But maybe they aren’t all that clever. Maybe that’s how they differ from humans. Afraid not. Scientists have documented that in between receiving information and acting on it, crows brains are capable of sorting by abstract categories (like the number of objects in a group or color), they can remember things both in the short term and the long term, they can link input from different senses together - which apparently is rare in the earthly animal kingdom, and they can develop conceptual rules like sameness or difference. This means they have adaptive coping strategies for gathering food, are flexible in providing for future needs, and swiftly extract general principles to guide behavior in new situations. Quite literally mind blowing.

Because crows have all these facets of cognition which are believed necessary for higher intelligence, brain researchers now are asking “Do crows have a theory of mind?” Having a theory of mind means a creature understands that other beings have a different state of mind than their own - they might be able to see things I can’t or might steal my food if they see me hide it. Both crows, and their close cousin, ravens have been shown to change their food-hiding-behavior when they thought they were being watched versus when the line of sight to other birds was obscured which suggests they both have a theory of mind.

But if all that’s too abstract to convince you that crows are smart, check out this video. Check it out even if you are already convinced crows are brilliant, because this video , of the crow nicknamed 007, is reality shifting. I’ll say no more, but delightedly note that the crows in this study are released after three months in captivity.

Less gently, some scientist have dissected crow brains to try to understand how a creature with such a small brain could possibly be so intelligent. I’d always understood that brain size determined intelligence, but that is quite outdated. Instead, many biologists now think brain to body mass as an indicator of intelligence. On this scale, crows rival humans. However, a new study has challenged this paradigm by looking at brain to body mass ratios across the fossil record. The study found that over the eons the brain to body mass ratio was often changed by non-intelligence pressures. For example, sea lions gained body mass to stay warm, thus reducing their brain-to-body ratio, but not changing their intelligence.

So now, new ideas are emerging that brain organization is the key to intelligence. Crow brains are organized vastly differently from human ones. While mammals have a layered cerebral cortex, this is non-existent in birds. Instead, the end brain of birds is more of a central nucleus with organized circuits attaching to different parts of the brain. Birds, therefore, have twice as many neurons as primates for a given mass of brain. This suggests that intelligence evolved along two different paths - one for birds and mammals. To tie back to the importance of crow families, it has been suggested the long adolescence of crows, enabled by the dedication of the crow family, promotes greater brain development. (Acherman, The Genius of Birds)

As humans, we’ve continually updated our reasoning for why we are special and distinct from the “lower" animals. We used to say it was tool use, but Jane Goodall found that chimpanzees use tools. And now we’ve seen tool use in many other species, including crows. Some people claim it is our language which is unique - though we know that crows, whales, elephants, and prairie dogs, to name a few, communicate with one another about food sources, dangers, and where they are. Perhaps it is our complex thinking, or our awareness of others’ states of mind that makes us unique. Perhaps it is that humans have a more developed culture. But some animals have indications of each of these traits. Perhaps humans are unique in having all of them? Yet crows have indications of all these things, as I suspect elephants and dolphins do. I have found it profoundly settling to learn that humans are not so different from the playful crow. The thought nestles me right back into the start of this unexpected journey of learning about crows - when I first witnessed the crow river flying overhead. That everything and nothing magical feeling of connectivity. I’m delighted that I get to watch and observe, and speculate about, these fascinating creatures, out my window, in my garden, and almost everywhere I go. Caw caw caw.