Tag: corvids

  • Deception in Animals: Which Species Lie and What That Tells Us About Cognition

    A male mourning cuttlefish wants to mate with a female. A rival male is watching. The cuttlefish does something that should be impossible for a creature with a 10-month lifespan and no social upbringing: he splits his body display in half. On the side facing the female, he shows courtship coloration — bright, patterned, unmistakably male. On the side facing the rival, he simultaneously displays female patterning — muted, cryptic, a disguise designed to convince the rival that no competition is present. Two contradictory signals, broadcast from one body, targeted at two different audiences at the same time. That’s not camouflage. That’s not instinct in any simple sense. That’s an animal producing a lie calibrated to two different observers with two different perspectives, and executing it in real time with chromatophores instead of words.

    The question of whether animals deceive each other is settled — they do, constantly, across hundreds of species. The question that matters is what kind of deception they’re performing, because the answer tells you something fundamental about what’s happening inside their nervous systems. And a May 2025 paper in Trends in Ecology & Evolution by Drerup, Garcia-Pelegrin, Clayton, and colleagues just reframed the entire field by proposing cephalopods — not primates, not corvids — as the ideal model organisms for studying the most cognitively demanding form of deception.

    The spectrum

    Not all deception is created equal, and the distinctions matter more than the examples. At the bottom of the spectrum, you have deception that requires no cognition at all. Harmless butterflies evolving wing patterns that mimic toxic species is deception — it communicates false information to predators — but nobody claims the butterfly is “lying.” The misinformation is encoded genetically over evolutionary time, not produced by an individual making a decision. A stick insect that looks like a twig is deceiving every bird that passes without doing anything except existing. This is deception without a deceiver.

    One step up, you get deception that involves behavioral flexibility but may still be conditioned rather than cognitively strategic. Firefly femmes fatales — females of the genus Photuris that mimic the flash patterns of Photinus females to lure Photinus males close enough to eat them — produce species-specific flash codes that attract prey. The behavior is adaptive, it’s flexible (the predator adjusts flash timing to match different prey species), but it may operate through relatively simple learning mechanisms rather than any representation of what the victim “believes.”

    At the top sits tactical deception — deceptive behavior that is flexibly adjusted based on the identity, perspective, or inferred knowledge of the observer. This is the category that implies something approaching theory of mind, the capacity to understand that another individual’s knowledge or perspective differs from your own and to exploit that asymmetry. Tactical deception has been documented primarily in two vertebrate groups: primates and corvids.

    The primate evidence

    Primates are the best-studied tactical deceivers. Research across 18 species has demonstrated a strong correlation between the frequency of tactical deception and the size of the neocortex — suggesting that the capacity to deceive conspecifics was itself a selection pressure driving brain evolution, a hypothesis known as the Machiavellian intelligence theory. Chimpanzees suppress food calls when dominant individuals are nearby, concealing discoveries rather than sharing them. Subordinate males lead dominant rivals away from hidden food by walking confidently in the wrong direction, then doubling back to retrieve it when the dominant is out of sight. Baboons have been observed using false alarm calls — predator warnings issued when no predator exists — to scatter competitors away from food resources.

    The key distinction is context-dependence. A chimpanzee doesn’t suppress every food call — she suppresses them selectively, when a specific dominant individual is present and when the social cost of sharing outweighs the benefit. The behavior varies with audience, which means the animal is tracking who knows what, who can see what, and what the consequences of being detected are. Whether that constitutes genuine “mind-reading” or a sophisticated learned association between behavioral cues and outcomes is the debate that has occupied comparative cognition researchers for decades. The behavior looks like theory of mind. Proving it is theory of mind rather than behaviorally flexible conditioning is extraordinarily difficult, because the observable output is identical.

    The corvid evidence

    Corvids — jays, ravens, crows — match primates in deceptive sophistication despite being separated by 320 million years of evolution. Nicola Clayton’s lab at Cambridge has produced some of the field’s most striking results. Western scrub-jays that have been observed caching food by another jay will return later, when the observer is absent, and re-cache the food in a new location — but only if the cacher has personal experience of having stolen food from others. Jays that have never stolen don’t re-cache. The implication is that the cacher is projecting its own experience of thievery onto the observer — reasoning, in effect, “I would steal from that cache, so this jay probably will too.”

    Ravens observed by Thomas Bugnyar show similar patterns. They monitor the gaze direction of competitors during caching events and adjust their concealment strategies based on whether they believe the competitor has visual access to the cache location. A 2016 study demonstrated that ravens can track whether an observer can see through a peephole — adjusting their caching behavior based on whether the peephole is open or closed, even when no actual observer is present. The researchers argued this showed an understanding of another’s visual perspective independent of behavioral cues, though the interpretation remains contested.

    Garcia-Pelegrin’s work at Cambridge has added another dimension: using magic tricks as experimental tools. Jays were shown sleight-of-hand coin vanishes and real transfers. The birds tracked the real transfers accurately but were fooled by the sleights — demonstrating that they form predictions about object permanence and manual actions that can be violated, just as human audiences are fooled by the same techniques. The cognitive architecture that makes you susceptible to a magic trick is the same architecture that allows you to deceive others.

    The cephalopod frontier

    The 2025 Drerup et al. paper in Trends in Ecology & Evolution argues that cephalopods — octopuses, cuttlefish, and squid — are the ideal organisms for studying tactical deception because they combine two things no other taxon offers at the same scale: an extraordinarily rich behavioral repertoire of naturalistic deception and cognitive abilities sophisticated enough to potentially support flexible, audience-dependent deployment.

    The mourning cuttlefish’s split-body display is the poster case, but it’s not the only one. Common cuttlefish flash false eyespots to scare approaching predators — but only to visually oriented predators, not to those that hunt by smell, suggesting the behavior is calibrated to the sensory capabilities of the audience. Giant Australian cuttlefish males that are too small to win fights adopt female coloration and posture to sneak past rival males and access females — a transient, context-dependent mimicry that is abandoned the moment the social environment changes. Female opalescent squid mimic male appearance by flashing a white stripe to deter unwanted mating attempts, deploying the deception only under specific conditions.

    The critical question the paper raises is whether these behaviors constitute conditioning — learned responses to specific cue-outcome pairings — or tactical deception, which requires the deceiver to evaluate information about the observer and adapt its strategy based on the observer’s perspective. The distinction matters because cephalopods have nervous systems organized completely differently from vertebrates — 500 million neurons in an octopus, most distributed across peripheral ganglia in the arms rather than concentrated in a central brain. If cephalopods perform tactical deception, it evolved independently from the primate and corvid lineages, through entirely different neural architecture, which would tell us something profound about what kinds of nervous systems can support perspective-taking and flexible social cognition.

    What deception tells us about minds

    The ability to lie is — paradoxically — one of the strongest indicators of cognitive sophistication. A truthful signal requires only a detection system and a broadcast mechanism. A deceptive signal requires, at minimum, a model of what the receiver expects, an ability to generate a signal that violates reality while matching that expectation, and — in the case of tactical deception — a capacity to adjust the deception based on who’s watching. Every step up the deception spectrum adds a layer of cognitive complexity that brings the deceiver closer to what we’d recognize as a mind.

    The convergent evolution of tactical deception in primates, corvids, and potentially cephalopods — three lineages separated by hundreds of millions of years and running on radically different neural hardware — suggests that the capacity for deception isn’t a quirk of primate brains. It’s a solution that evolution converges on whenever social complexity creates enough pressure to make manipulating others’ behavior worth the cognitive investment. The cuttlefish that splits its body display between two audiences and the chimpanzee that leads a rival away from hidden food are solving the same problem with different equipment. The problem is other minds. The equipment is whatever nervous system natural selection had to work with.

    We cover deception alongside mirror neurons, dolphin naming, tool use, and 20 other investigations into what animal nervous systems can do across our Animal Culture & Knowledge course — where the question isn’t whether animals have minds but what kind of minds they have, and how we’d know.

  • Corvid Intelligence: Tool Use, Planning, and Why Crows Hold Funerals

    A New Caledonian crow named Betty, in a 2002 experiment at Oxford, bent a straight piece of wire into a hook to retrieve food from a tube. She had never seen wire before. She wasn’t trained to bend it. She looked at the problem — food at the bottom of a vertical tube, a straight wire that couldn’t reach it — and manufactured a tool from a novel material, on the spot, to solve a problem she’d never encountered. That single observation kicked off two decades of research into corvid cognition that has systematically demolished the assumption that complex intelligence requires a primate brain, a mammalian cortex, or 300 million years of shared evolutionary history with humans.

    Corvids — the family that includes crows, ravens, jays, magpies, and jackdaws — have brains the size of a human thumb. They have no neocortex, the structure that in mammals is responsible for the cognitive functions we associate with intelligence: planning, reasoning, abstract thought, self-awareness. They produce comparable cognitive outputs using entirely different neural architecture, which means either intelligence is less dependent on specific brain structures than neuroscience assumed, or corvids evolved their way to the same destination through a route nobody predicted.

    https://open.spotify.com/show/7kYYn1bsA68hcfeT1YYehh?si=ae8656690bc643fb

    Tool use: not the party trick it looks like

    New Caledonian crows are the corvid species with the most sophisticated tool use, and the research on them has gone well beyond “crow uses stick to get food.” In wild populations on the Pacific island of New Caledonia, these crows manufacture tools from pandanus leaves by tearing them into specific shapes — stepped, tapered, or wide — to probe insect larvae from tree bark. The tool shapes are consistent within populations and vary between populations, which means the techniques are culturally transmitted rather than genetically encoded. A young crow learns to make tools by watching older crows. If the older crows die before transmitting the technique, the knowledge disappears. This is culture — the same mechanism that transmits human skills across generations — operating in a bird with a brain that weighs 14 grams.

    In laboratory settings, the cognitive demands of corvid tool use have been tested with increasing rigor. Gruber and colleagues, in experiments published in Current Biology, presented New Caledonian crows with metatool problems: multi-step tasks where one tool must be used to obtain another tool, which is then used to reach food, with each stage of the problem out of sight of the others. The crows had to mentally represent the location and identity of tools and apparatuses they couldn’t see while planning and executing a sequence of tool behaviors. They succeeded — maintaining working representations of objects across spatial separation and planning one to two steps ahead. The researchers concluded that New Caledonian crows can use mental representations to solve sequential problems, a capacity previously attributed only to humans and great apes.

    A 2020 study in Proceedings of the Royal Society B pushed further. Crows learned a temporal sequence: they were shown a baited apparatus, given a choice of five objects five minutes later, and given access to the apparatus ten minutes after that. At test, the crows selected the correct tool for the specific apparatus they’d been shown — choosing the right tool for the right future task while ignoring previously useful tools and a low-value food item. The study’s conclusion: New Caledonian crows plan for specific future tool use. This capacity — selecting a tool now for a task that will occur later, based on a mental representation of what that future task requires — was previously considered a defining feature of human intelligence. Corvids and humans shared a common ancestor over 300 million years ago. Whatever cognitive machinery the crows are using, they evolved it independently.

    Funerals: danger assessment, not grief

    When a crow dies, other crows gather. They emit alarm calls — loud, repetitive scolding vocalizations — that attract additional crows to the scene. Dozens of birds may congregate around the body, observing it from nearby perches, sometimes flying down to inspect it, sometimes sitting in silence. To a human observer, it looks like mourning. The scientific explanation is more interesting than mourning.

    Kaeli Swift, a behavioral ecologist at the University of Washington working under corvid cognition researcher John Marzluff, conducted a two-year experiment across over a hundred sites in Washington State. She established feeding stations to attract local crows, then introduced a dead crow (a taxidermied specimen) while a masked human volunteer stood nearby. The crows responded to the dead crow with alarm calls and gathering behavior. More importantly, they subsequently avoided feeding at that location — and they associated the masked person with danger, responding with alarm calls when that person appeared again, even without the dead crow present. The crows learned from the death scene. They identified a potential threat (the person near the dead crow), memorized the threat’s face, and modified their behavior to avoid the area and the individual. Weeks and months later, they still recognized and responded to the mask.

    Crows respond far more strongly to dead crows than to dead birds of other species. They largely ignore dead pigeons, robins, or other non-corvid birds placed in their territories but react intensely to dead members of their own species. Some studies suggest they respond more strongly to familiar individuals than to unfamiliar crows, indicating they may recognize specific community members even in death.

    The “funeral” is not a ceremony. It’s a threat assessment protocol. The crows are investigating the scene to determine what killed the dead crow, whether that threat persists, and how to avoid it. The alarm calls broadcast the danger to the wider community. The subsequent avoidance behavior encodes the lesson into the population’s behavioral repertoire. Marzluff’s research demonstrated that crows can remember human faces that posed a threat for years — and they transmit this knowledge to crows that weren’t present for the original event. A crow that never saw the masked person holding a dead crow will nonetheless scold that person if other crows in the community do, because the social alarm response propagates through the group.

    The behavioral function is pragmatic: collective intelligence applied to mortality data. The emotional dimension — whether crows experience something analogous to grief — remains scientifically unresolvable. Swift’s position is candid: she believes crows have emotional intelligence, but testing that scientifically is impossible because there’s no way to access what’s happening at an emotional level inside an animal’s brain. What’s measurable is the behavioral output: crows process death, learn from it, remember the context, and share the information. Whether they feel anything while doing it is a question the methodology can’t answer.

    What corvid brains do differently

    The corvid brain lacks a neocortex. In mammals, the neocortex is the seat of higher cognitive function — the structure that expanded dramatically in primates and reached its maximum density in humans. Corvids achieve comparable cognitive outputs using a structure called the pallium, which is organized differently from the mammalian cortex but performs analogous functions. The neuron density in the corvid pallium is remarkably high relative to brain volume — corvid brains pack more neurons per gram than most mammalian brains.

    A 2025 paper in Animal Cognition by Veit and colleagues explored the “dimensions of corvid consciousness” — a research framework asking not whether corvids are conscious but what aspects of consciousness their neural architecture could support. The paper argues that corvid brains process sensory information, maintain working memory, and generate flexible behavioral responses through neural pathways that are structurally distinct from but functionally analogous to mammalian circuits. A German neurobiologist trained two crows — Glenn and Ozzy — to peck at “yes” or “no” targets to indicate whether they had detected a faint light, demonstrating analytical introspection: the crows reported on their own perceptual states, a capacity associated with subjective experience.

    The convergent evolution angle is what makes corvids matter for neuroscience rather than just for animal behavior. If complex cognition can evolve independently in a brain that is structurally unrelated to the primate brain, then intelligence is not a property of a specific neural architecture. It’s a property of certain computational principles — neuron density, connectivity patterns, feedback loops — that can be instantiated in multiple biological substrates. The corvid brain is evidence that there is more than one way to build a mind, and that the way mammals did it is not the only way it can be done.

    Corvids sit alongside octopuses as the strongest natural evidence that intelligence is convergent rather than unique. We cover corvid cognition alongside cuttlefish camouflage, electroreception, and the full landscape of how animal brains solve problems humans assumed required human brains across our Neurozoology course — including why a 14-gram brain that last shared an ancestor with yours 300 million years ago can plan for the future, manufacture tools from materials it’s never seen, and hold a funeral that’s more operationally useful than most of ours.