`We should keep closer eye on crows. One thing’s for sure: they’re keeping close eye on us. Maybe they think we’re somewhere near their level.

Everyone knows crows are pretty darn smart. They imagine and craft simple tools for extracting food from hard-to-reach places. YouTube features a crow dropping breadcrumbs at water’s edge to attract and catch fish. Crows grasp statistical probability. Pecking for food pellets on keys pitched at varying probabilities of reward, they consistently choose a higher probability key over a lower, the more so the further apart in probability the two keys are. Faced with tricky puzzles to fetch a food reward, crows form and execute multi-stage plans.

Hows and whys of crow intelligence are essentially two-fold: big brains and culture.

Recent science indicates that crows began rapid dispersal from Central Asia roughly 10 million years ago (mya), accompanied by rapid proliferation of new species. This sudden expansion owed to a specific suite of traits: 1) longer wing lengths yielding increased flight capacity and geographic range; 2) increased size providing competitive advantage over rival types; and 3) bigger brains relative to body size (brain-to-body ratio or BBR), favoring behavioural flexibility and habitat adaptability.

Freshly-arriving crows could outlast initial maladaptation long enough to generate new species. Dietary omnivorousness favored adaptability, often achieved through modification of beak sizes and shapes, better to exploit specific habitats. Nature’s Swiss Army Knives, crow beaks can rip, tear, cut, crush, pick, probe, penetrate and spear almost anything.

Equally important, crow brains feature a super-sized frontal cortex analog, comparable in proportion to body size with non-human apes, whales and dolphins. This ‘nidopallium’ consists of densely packed and interconnected nerve cells facilitating information storage, processing and coordination. Such a brain can run the body properly but have plenty of room left over for cognitive functions.

In just a few million years, crows radiated across the entire globe, almost. Failure to colonize Antarctica and New Zealand requires no explanation. Puzzling failure to reach South America probably owes to: 1) migration from Asia to North America by way of far-distant Alaska; 2) declining seasonal migration in ever-warm Mexico and Central America resulting in stalled exploration of new territories among the small number of crow species living there; 3) a watery gap separating North and South America until the volcanic rise of the Panamanian isthmus as recently as three mya.

Crows manifest a high degree of social learning within communities and families, a pattern many scientists call ‘culture.’ Hallmarks of social learning include imitation at a basic level and teaching at a higher level. Socially learned behaviour, neither genetically wired nor acquired through individual experience alone, prevails in environments and niches that vary continually but not too wildly or quickly. In highly stable environments and niches, social learning goes unneeded: behaviour genetically encoded through natural selection suffices for survival. In highly fluctuating environments and niches, on the other hand, social learning can gain no foothold: any potentially helpful culture offers no real advantage if circumstances change radically over the lifespan of a single animal.

For crows, human communities seem to hit that sweet spot between prolonged stasis and chaotic variation. Scavenging off hunter-gatherer leftovers proved an excellent way for crows to thrive. Agriculture and cities: even better.

We speak of crows as ‘generalists’ because they prosper in such disparate habitats. A big part of that generalism is their omnivorousness. Crows eat fruit and seeds. They kill and eat small animals of all kinds. They consume lots of garbage and roadkill. (Thank you!) Crows will eat pretty much anything they see anyone else eating, up to and including cheese puffs. But in another sense crows emerge more and more as specialists. Their specialty is people. This is quintessentially true of our local South Asian House Crow. It lives only near human settlements.

Crows are nothing if not playful. Many scientists view play as an accompaniment and even a prerequisite of high intelligence. Tales of crow playfulness number in the hundreds or more: king of the mountain, follow the leader and sliding down snow slopes to name just a few. I’ve read a cryptic account of crows playing ‘tennis’ on a court in Japan. Two crows faced one another on opposite sides of a net while a third flung balls into it and they all watched the balls roll. (What’s missing here is how the balls got flung: beak? feet? wing?) Anyhow, this could represent cultural transmission of play behaviour between species. Imagine them figuring out that it’s even more fun flinging the ball over the net!

Some crows perform decent imitations of human vocalizations, probably just for the fun and challenge it. As I worked on this article, I decided to reach out to crows who visit the roof-shaded deck where I sit working. I set out some crumbled crackers and popcorn, hoping for some contact. My offerings disappeared several times while I was absent but that could have been due to foraging by chipmunks or birds other than crows.

Then one morning a smallish crow fluttered in, perched on a beam above me and began checking me out, tilting its head this way and that. I said ‘hi’ a few times and then it started to respond after every ‘hi’ with a vocalization of its own. The fascinating thing is that its calls began to vary from one another: quoo, kraaw, qree. It looked for all the world like it was trying to mimic me. I needed to leave after a few minutes, but I think it might come back. Crows recognize individual human faces far more ably than we recognize theirs.

I’ve personally witnessed only one episode of crow tool use. A while back, after a walk on the paddyfield exercise track, I stood drying in the breeze across a water channel from a swampy stand of forest. I heard a crow caw and sought to glimpse it in the canopy. It departed its perch and flew a few metres along the forest edge. Then it plucked a bright green new leaf and carried it across the channel, settling on the flat solar panel atop a lamp near me. I couldn’t see exactly what was happening because of the angle, but it seemed to peck a bit before nudging the leaf so that it fell to the ground.

It flew back over the channel, plucked a similar leaf, and darted back to the solar panel. Again: poke, fiddle and drop. But this time another crow appeared and joined the fiddle phase. It seemed to get a little goblet in its beak before gulping it in. They both flew off away from the channel. Just then, a third (I think) crow swooped over the channel, plucked a bright green leaf and flew back over to the solar panel: poke and fiddle. As I stepped closer, it flew into a nearby tree with the leaf.

Investigating the two dropped leaves, I found a ragged small pecked-looking hole in each, along with white-clear, filamentous, mucus-y, sticky-looking spots and streaks on one side of the leaf. With some internet poking (sorry!), I solved the mystery: aphids, those pesky insects ravaging your garden plants!

Usually wingless, aphids enjoy repasts of sugary tree sap, found in special abundance on green new leaves. They excrete that sticky stuff I saw, known as ‘honeydew.’ Aphids apparently make a sweet protein-y treat for my clever neighborhood crows.

I waited to see if they would resume but the episode seemed to be over. Was this a case of crows two and three(?) learning something new from crow one or is it something they have all been doing all the time already? The former seems less probable but why was there this apparently sudden but brief burst of the behaviour? Maybe crows aren’t that keen on sweets? (Answer: they aren’t.)

As with most or maybe all high-IQ creatures, crow braininess relies on sociability. Parents care for chicks well after youngsters can fly on their own. Mature chicks often remain with parents for extended periods, helping in the care, feeding and protection of younger broods. This may serve as apprenticeship in raising their own future broods.

Unlike the slow pace of genetic selection, cultural transmission can enhance life chances within a single generation. Birds with useful socially-learned habits due to slight superiority in braininess may find themselves competitively advantaged in finding mates and fostering survival in their offspring. This could feed back into genetic selection, producing increasingly brainy and culturally adept crows. Scientists speculate that such a positive feedback loop may operate with accentuated intensity in urban habitats with their ever-emerging novelties. Settlement-savvy super-crows seem to be expanding in range and numbers. Our House Crow may be getting even smarter as we watch.

Crow communication follows cultural trajectories. Calling styles evolve and vary from flock to flock in regional dialects. Crows joining a new flock will mimic calling styles of dominant birds. Crows use varying calls specific for mates, family, begging, food finds and different kinds of predators. They deploy variance in pitch, intensity, volume, rate and duration to convey purpose and emotion. They also communicate with gesture: movement, posture, feather display, eyeblinks and pupil dilation. These calls and gestures appear to be learned from elders and peers, not genetically pre-programmed.

Sophisticated crow communication should not, however, be confused with ‘language’ as we practice it. Enthusiastic and well-funded recent A.I. research into de-ciphering animal ‘languages’ will come up empty as to the ‘language’ part. Language as a capacity for nearly limitless comprehension, imagination, abstraction, experimentation, innovation and criticism can emerge only through a prolonged evolutionary tutelage in complex toolmaking and tool use.

Emerging from African jungle, smart, awkward and vulnerable apes needed to adapt to life on the spreading savanna. Needing help with both predators and prey, they began to forge sophisticated tools. Among animals alive today, only we and our genus Homo cousins completed such an evolutionary journey.

Language is not just a highly sophisticated communicatory system, though it is that of course. More deeply, it is a highly complex, organized sequential way of thinking about how to execute tasks (toolmaking, tool use, hunting and gathering) before and while undertaking them. Language is how genus Homo learned to make complex tools. And vice versa: learning and teaching how to make complex tools is how language evolved. Language and sophisticated toolmaking both depend for meaning and effectiveness on names for things, actions and qualities and on complex sequential arrangements. Linguistic capacities and tool use capacities arise in the same regions of our brains. One cannot exist without the other.

Somewhat sadly, it seems that only a single language-wielding species can rule the planet for a prolonged period. Right now, that’s us. The rest of genus Homo has been exterminated, absorbed, interbred, outcompeted, out-tooled and outlasted by lucky us. We’re very likely genus Homo’s last stab. If we vanish, language and all thought that it fosters may vanish as well for a long time, maybe forever. But not necessarily.

Does human-crow cultural conjunction imply evolutionary co-dependence such that our demise would be theirs as well? Not bloody likely. Remember, crows hold roughly an eight-million-year head start over us in brain super-sizing (though we did it much faster and took it much further, of course). Were we to disappear, let’s say a million years from now, crows would suffer from lack of powerline perches, garbage dumps and fast-food leftovers. Our ubiquitous and human-specialized House Crow might find the going especially rough. But crows in general would surely pull through.

Maybe there would be a crow species, maybe even our newly-challenged House Crow?, slightly larger by then, with slightly higher BBR. Their offspring might start growing taller: brains bigger, using sharp objects against aerial predators and large ground prey, going flightless, letting wings become claws and then hands, leaning even further into intensive, prolonged nurturing of their chicks. As they exploit the detritus of our crumbled civilization, might they start to specialize in complex toolmaking and stumble into language? Planet of the Crows? If so, those oh-so-useful beaks might just get left by the evolutionary roadside. 

 

Writer, lawyer and former law professor, Mark Hager lives with his family in Pelawatte. [email protected]; https://www.linkedin.com/in/mahager/

 

Further Reading

Books

Marzluff, et. al., In the Company of Crows and Ravens

Savage, Crows

Articles and Posts

Garcia-Porta, Niche Expansion and Adaptive Divergence in the Global Radiation of Crows and Ravens

Winkler, Crow Makes Wire Hook to Get Food

Caccamise, Roosting Behavior and Territoriality in American Crows

Chamberlain, Selected Vocalizations of the Common Crow

Naturalist Notes: Wolves and Ravens