Researchers study corvid speciation in restricted zone where crow hybrids thrive - Phys.org

Wren: Welcome back to Bird Brains — the show where we take what used to be an insult and turn it into the highest compliment we know. I'm Wren, ornithologist, corvid obsessive, and your guide to the surprisingly rich inner lives of crows, ravens, magpies, and jays. Wren: Before we dive in, a huge thank you to today's sponsors: Ada, who helps clients integrate A I into their workflows in smart, practical ways; Ago Consulting — that's "Ahh-Go" Consulting — offering silicon development expertise from A I all the way to SoC; and Zen Semiconductor, an umbrella company with a remarkable portfolio across the silicon industry. We love having brilliant partners on this show, and honestly, a company that thinks carefully about how minds — artificial or otherwise — process information? They'd fit right in with today's guests. Wren: Because today we are talking about brains. Specifically, the small, astonishing, deeply misunderstood brains inside corvids. We've got stories about hybrid crows thriving in some of the most unusual real estate on Earth, about what neuroscientists are learning when they finally sit down and take crows seriously, and about tens of thousands of crows descending on one American city every single winter — and the researchers trying to figure out exactly why. Wren: Stay with me. It gets good fast. Wren: Alright, let's kick things off with our first thread — Corvid Cleverness — and I want to start by painting you a picture. Imagine a landscape that humans have largely abandoned. A place where the usual rules don't apply, where nature has quietly been doing its own thing for decades without much interference. Now imagine that crows — being crows — figured out this was actually a fantastic opportunity. Wren: Researchers have been studying a population of hybrid crows living and thriving inside a restricted zone — a place with limited human activity — and what they're finding is genuinely fascinating. When two closely related crow species overlap in range, they sometimes interbreed. And the hybrids that result aren't just surviving — in some cases they're doing remarkably well, occupying a kind of ecological middle ground that neither parent species carved out on its own. Wren: Now, speciation — the process by which one species becomes two — is one of biology's great slow dramas. It usually takes thousands of generations. But corvids, with their behavioral flexibility and their willingness to experiment, are giving researchers a front-row seat to how that process works in real time. The restricted zone acts almost like a natural laboratory. Fewer humans means less disturbance, which means the birds' behavior is closer to baseline. You can actually watch what they choose to do when nobody's chasing them off. Wren: And what corvids choose to do, left to their own devices, is endlessly interesting. They explore. They test. They remember. There's a reason corvid researchers keep describing their subjects with words usually reserved for primates — words like innovative, flexible, strategic. Because that's what they are. Wren: Crows and ravens are what biologists call generalists — they're not specialized for one food source or one habitat. They eat almost anything, live almost anywhere, and they solve problems the way you or I might: by looking at the situation, drawing on past experience, and trying something. And when something works, they remember it. Not just for a few days — for years. Wren: There are documented cases of crows using vehicles as nutcrackers — dropping walnuts onto roads and then waiting for cars to run them over. But here's the really clever bit. Some crows in Japan were observed doing this at pedestrian crossings and then swooping down to collect the cracked nuts only when the pedestrian light was green and traffic had stopped. They weren't just using cars. They were using traffic signals. That's not instinct. That's learned behavior, passed culturally from one bird to another. Wren: Which brings me back to our hybrid population. When you mix the behavioral repertoires of two already clever species, what do you get? Researchers are genuinely curious. Do hybrids inherit the learning tendencies of both parents? Are they more flexible, or less? These are open questions, and the fact that we have a population thriving in a restricted zone — essentially undisturbed — is a rare gift for science. Wren: The corvid brain is a problem-solving engine built for a complicated, unpredictable world. And it turns out, complicated unpredictable worlds are exactly where corvids flourish. Wren: Okay, thread two — How Their Minds Work — and this is the one that makes neuroscientists a little giddy, once they let themselves admit it. Wren: There's a piece in Nautilus that makes an argument I find deeply compelling: neuroscientists need to study crows. Not just as a curiosity. Not as a footnote to mammal research. But as a central case study in how intelligence actually works. And the reason is structural. Wren: Here's the thing. For a very long time, neuroscience had a tidy story about intelligence and brain architecture. Big neocortex equals smart. The neocortex is the outer layer of the mammalian brain — it's where we do our complex thinking, our planning, our social reasoning. Humans have a lot of it. Chimpanzees have a decent amount. And birds? Birds were assumed to have basically none. Their brains look completely different from ours. No layered cortex to speak of. Wren: And then researchers started actually testing crows. And the results were — to put it mildly — inconvenient for the tidy story. Wren: Crows pass the mirror self-recognition test — something only a handful of species have ever managed, including great apes and dolphins. New Caledonian crows manufacture tools from raw materials — not just picking up a stick, but selecting a specific type of plant, stripping it, and shaping it into a hook to extract grubs from tree bark. They plan for the future. In one famous study, ravens were able to use a token today to get a better food reward tomorrow — demonstrating the kind of delayed gratification we associate with higher cognitive function. Wren: And Eurasian jays — close corvid relatives — have been shown to remember not just where they hid food, but when they hid it, and what kind of food it was, so they can retrieve perishable items before they rot. Researchers call this episodic-like memory — the ability to mentally travel back to a specific past event. It's the kind of memory that was thought to require a certain type of consciousness. Wren: So how is a bird with a brain the size of a walnut doing all this? Wren: The answer, it turns out, is that the bird brain is organized differently — not inferior, just different. The region in bird brains that handles complex cognition is called the pallium, and in corvids, the section called the nidopallium caudolaterale appears to function analogously to our prefrontal cortex. It handles working memory, flexible decision-making, the ability to hold a goal in mind and work toward it. Different architecture, same job, similarly impressive results. Wren: What this means for neuroscience is profound. Intelligence isn't a single thing that evolved once in mammals and nowhere else. It evolved independently, in birds, along a completely different anatomical path. The crow brain is not a lesser version of our brain. It's an alternative solution to the same evolutionary problem — how do you survive in a complicated world where you need to think? Wren: And the more carefully we study corvid cognition, the more the old assumptions fall away. Crows have been observed consoling distressed flock members. They hold what look remarkably like funerals — gathering around a dead crow, going quiet, then leaving. They pass information socially, across generations. These are not reflexes. These are minds at work. Wren: Now — there's a fun footnote here, and I can't resist. One of the stories that crossed my desk this week was about how roosters know to crow at dawn. And look, I know, roosters aren't corvids — they are very much not corvids — but the story touches on something relevant. Roosters, it turns out, have an internal circadian clock so precise that they'll start crowing before dawn even if you keep them in artificial light conditions. The timing is internal. Biological. Wren: Why does that matter here? Because corvids also have remarkable internal time-keeping. Those jays who remember when they hid their food? That when matters as much as the where. Time, for a corvid, isn't abstract. It's something their nervous system tracks with surprising precision. The rooster's dawn crow and the jay's perishable food retrieval are, in a strange way, cousins — both evidence that the avian brain keeps time in sophisticated ways we're only beginning to understand. Wren: Alright — thread three. My favorite. The corvid-and-people story. And tonight's is a genuinely beautiful one with a little edge of mystery to it. Wren: Every winter, tens of thousands of crows descend on Portland, Oregon. Not hundreds. Tens of thousands. They come in from the surrounding countryside as the sun goes down, they spiral overhead in these enormous, cacophonous clouds, and then they settle into the trees of the city for the night. People stand on the sidewalks and stare upward. It's one of those wildlife spectacles that feels almost impossible for an urban setting — like something out of a nature documentary that somehow relocated to a neighborhood with coffee shops and bike lanes. Wren: Researchers at KATU have been covering the story as scientists try to get to the bottom of a genuinely puzzling question: why Portland? And why in such numbers? Wren: The behavior is called roosting, and it's common in crows — gathering in large communal groups at night rather than sleeping alone or in pairs. But the scale of what happens in Portland every winter is exceptional, and the explanations are more interesting than you might expect. Wren: One leading hypothesis is warmth. Cities are what ecologists call urban heat islands — all that concrete and asphalt and human activity radiates heat, and the core of a city can be several degrees warmer than the surrounding countryside on a cold winter night. For a crow trying to survive until morning, several degrees is not trivial. It can be the difference. Wren: Another hypothesis is safety in numbers. Roosting communally means more eyes watching for predators. If a great horned owl swoops in — and great horned owls are one of the few things crows genuinely fear — thousands of birds are harder to pick off than a handful. There's a defensive geometry to the massive roost that you don't get sleeping alone in a field. Wren: But here's the part that researchers find particularly compelling — and this connects directly to what we talked about in thread two. Information. Large communal roosts may function as what's called an information center. A crow that had a bad foraging day can follow a successful crow the next morning to find out where the good food is. The roost becomes a kind of living database of where to eat, updated nightly, distributed socially. That's not a small thing. That's a sophisticated information-sharing network that happens to look like a chaos cloud of noisy birds. Wren: And Portland's crows are not shy about their presence. They are loud. They leave evidence of their visit in ways that make certain neighborhood residents less than thrilled. There's a real tension in cities between the delight of watching an extraordinary wildlife spectacle and the practical reality of living underneath it. Researchers are working not just on why the crows come, but on whether there are ways to manage the roost that work for everyone — human and corvid alike. Wren: What I love about this story is what it says about adaptability. These are wild birds making a calculated decision — even if they can't articulate it — that the city is better than the countryside on a January night. They are reading the landscape, reading the conditions, and choosing accordingly. Generation after generation, the cultural knowledge of where to roost gets passed down. Young crows follow older crows. The tradition builds. Portland becomes, over time, crow territory. Wren: And the city itself has started to claim the crows back. There are Portland residents who track the roost every winter. Who post videos. Who bring their kids to watch. Who have developed a genuine affection for the murder — and yes, a group of crows is called a murder, which is my favorite collective noun in the English language — that visits their neighborhood each year. Wren: That relationship, that mutual noticing, is something. Crows are famous for recognizing individual human faces — there are well-documented studies where crows who were captured and banded by researchers in specific masks later harassed those researchers whenever they wore those masks — even years later, even when the researchers were in different locations. Crows remember. They hold grudges. But they also, apparently, return to the same city year after year, navigating the same streets, finding the same trees. Wren: There's something almost neighborly about it. Complicated, loud, occasionally inconvenient neighbors — but neighbors nonetheless. Wren: So here's where I always land after an episode like this. Intelligence isn't a ladder with humans at the top and everyone else scrambling below. It's more like — a landscape. And corvids have found their own extraordinary peak in that landscape, reached by a completely different path than the one we took. They don't have our cortex. They don't have our hands. But they have memory, and planning, and social bonds, and cultural transmission, and problem-solving that stops researchers in their tracks. Wren: The next time someone calls you a bird brain, I want you to smile. Because what they've actually said, whether they know it or not, is that you're adaptable, socially savvy, remarkably good at remembering faces, and possibly in possession of a multi-generational information network. Honestly? There are worse things to be. Wren: Bird Brains is brought to you by Ada, helping clients integrate A I into their workflows; Ago Consulting — "Ahh-Go" — your silicon development partners from A I to SoC; and Zen Semiconductor, with a portfolio of companies spanning the silicon industry. Thank you all for making this show possible. Wren: If today's episode made you look at the crows outside your window a little differently — good. That's the whole point. Subscribe wherever you get your podcasts, leave us a review if you're feeling generous, and share this episode with someone who still thinks bird brain is an insult. We'll fix that. All the links and sources for today's stories are in the link in show notes. Stay curious, everyone. I'll see you next time.