Corvid fact: corvids are flying bastards. Largeish, stout beaks, wide wingspan, usually dark colored, long leggy-footy bone stronger than others, the tarsus. Generally you think of crows and ravens, but jays are also in the corvid family and are colorful, as well as magpies and jackdaws.

corvid fact: if I wore a convincing wwalker mask and paraded around his house while holding a dead crow, his local crows would caw when they saw him and swoop at him

corvid fact: pinyon jays are social corvids in large flocks who observe others when they fight and infer their relative social status based on observation of abilities of others. They choose mates and are denied by potential mates on their ability to raise young, or lack thereof.

corvid fact: pinyon jays can remember exactly where they cached a pine nut months ago, and dig in the precise spot to retrieve it, without multiple trials.

corvid fact: corvids are aware of others and their compulsion to rob caches, and move their goods only when they are aware of having been seen or in the presence of thieves. They'll also pretend to cache food while keeping it concealed in their beak and cache it elsewhere.

corvid facts: scrub jays cache both perishable worms and nonperishable nuts, and will retrieve the former sooner than the latter.

corvid fact: the corvid's forebrain was originally thought to be simple since it did not have a layered neocortex like in intelligent mammals which have layered zones, instead it's a case of convergent evolution where the forebrain develops in clusters instead. While not at all homologous with the more clever mammals, it's functionally the same.

corvid fact: With each season, the hippocampus where location memory is made, grows as the nutcracker caches seeds high in fats for retrieval later in the year. With each new season it will shrink, effectively wiping the location memory, to repeat the cycle again later. They can recall cache location accurately even after it being buried in feet of snow. A diet high in fats is necessary for brain development of this degree, while the many favor pine seeds, humans discarding fast food could spur them evolutionary in thousands of years to come.

corvid fact: The HVC in the nidopallium in corvids is the center of the brain that produces and remembers vocalizations. Its function is identical to the Broca area in humans' frontal lobe. Damage to either would compromise language ability in both animals.

corvid fact: Songbirds don't produce sound with lips or their tongue, but the syrinx: each of the two bronchial tubes has a labia, a compliant membrane that oscillates with airflow to produce sound, each independently controlled, allowing it to produces two different pitches at the same time.

corvid fact: Corvids were once thought to be purely reactive: once stimulated, the brain takes in sensory information, tempers it with instinct or early life learned behavior, and reacts. This is not the case. Corvids take in sensory information, filter it through memory of experience, using a feedback loop between the thalamus, midbrain, and forebrain, re-stimulate neurons with previous sensory information to reconsider their actions before taking them, and forming new pathways learning from the observed result of their action. They have as much conscious thought as the higher mammals.

corvid fact: When learning a new vocalization, the thalamus and forebrain has a positive feedback loop, releasing dopamine on successful vocalization, re-enforcing the neural pathway. This positive feedback loop that learns a vocalization is done without actually vocalizing, but fully within the brain.

corvid fact: Crows have been observed to regularly chase squirrels and herd flocks of rock dove into fast-moving traffic to kill them, then eat the roadkill once traffic clears. Others work in pairs to chase and steer prey into windows. Tail pulling to steal food is also seen in animals, corvids and monkeys.

corvid fact: crows eat smaller, stupider birds by baiting them, then pouncing when their attention is on the bit of food left out for it. 

corvid fact: solving puzzles generally requires immediate positive feedback, and is not just a product of insightful planning. They can pull up food on a string if they can see it, but if the prize is hidden they have a hard time accomplishing the task, if at all.  Multi-step puzzles where they must manufacture or use a tool to fetch anoter tool to get to the end is still a positive feedback loop as there is a constant progress towards goal, but without feedback, the corvid brain will just move on to another action or strategy until options are exhausted.

corvid fact: An experiment used scrub jays in cages with multiple compartments, with one compartment receiving no food in the mornings. After a couple days they learned that it received no food in that compartment, and subsequently cached much of its food from the evening feeding in it speficically. This demonstrates future projection, insight, planning, and successful execution, not traits commonly thought of in birds.

corvid fact: geese are idiots and crows know this. Bread thrown to geese was rushed by crows and covered by them with leaves, confusing the geese that then wandered off to be idiots somewhere else. The crow, unlike many birds, doesn't forget about something once it leaves their sight. This also demonstrates a theory-of-mind that toddlers do not yet possess. The corvid knows its own thoughts and is also aware of the thoughts of another. 

corvid fact: Corvids observe body language and will follow a human's gaze to a potentially interesting object or food. If you want to try to conceal your treasure from a corvid, don't look at it. They'll even explore the area and around obstacles, not just a straight line. If you've a pot of gold behind a large rock, they'll look there for it too if you look at the rock. Also, dogs follow gaze, though less well. Don't point, monkeys point, look when trying to direct a dog's attention.

corvid fact: Corvid can count. In studies where students went into a blind to observe crows, the crows stopped their usual business and perched in the high safety of a tree. Students left, and not until all left did the crows return. This was repeated multiple times with different numbers of people. 

corvid fact: Corvids play, both among their own species, and with other birds and even mammals. During successful play, opiods are released in the brain providing reward, while dopamine is simultaneously released, increasing firing and strengthening the synapses formed by play upon expected and observed results of their actions. When results exceed expectations, dopamine is increased, providing a more significant learning moment.

corvid fact: Corvids seem to mourn their dead, perhaps in part because selection favors those who observe circumstances of death to warn of and avoid it in the future, perhaps because they now have to observe others in their flock to reevaluate their social standing, but actual grief is also likely considering the structure of their forebrain and the hormones released upon stress, such as a dead family member, or member of their own species.

corvid fact: When two corvids within a flock fight, onlookers will often console with mouthing and grooming, releasing endorphins and leading to reconciliation. They'll also attempt to help an injured member, protecting them from nearby threats if they lay injured, or trying to lift them and revive. However, it's also been observed that crows initially trying to help a fallen fledgeling would swiftly kill it instead when unsuccessful.

corvid fact: While cautious, they take calculated risk such as chasing away owls and hawks, housecats, dogs, eagles, and other superior predators. They don't always survive these ventures. Similarly, a solitary crow will also seek companionship with another species that would otherwise predate it. Corvids are social and require companionship, though not necessarily with their own species. Interspecies companionship is genreally restricted to younger corvids, but well old enough to be post-imprinting; they're aware that they're a crow and their friend is a dog, wolf, cat, or human.

corvid fact: Corvids recorgnize and remember not only faces, but cars, and particular animals. They will become comfortable and flock towards people, or their car arriving, that's known to feed them. Similarly, they'll scold those who have been seen as a threat after harassing, killing, or been seen approaching a dead corvid before their mourning period was complete. Knowledge will pass to others as they observe corvid and human interaction, either scolding with alert caws, or approaching for delicious peanuts.

corvid fact: While crows do not have predator-specific alarm calls, Siberian Jays, for example, vary the call to signify predator type and activity: a moving, perched, or attacking hawk.

corvid fact: PET scans on crows revealed that when they recognized a known dangerous face, the right brain lit up, just as human brains do in fearful settings, while exposure to the face of a feeder and caretaker, the left brain showed the most activity. Post-scan, those exposed to the dangerous face blinked significantly less, signifying a more active amygdala, associated with fear response. 

corvid fact: Corvids learn several ways: first hand experience, they remember faces of those who captured them; direct observation, they remember faces they see capture fellow corvids; imprinting behavior, they learn while young by observing parents scolding a learned dangerous face; and social learning, they observe the behavior of their peers, their scolding, follow their gaze, and associate behavior with knowledge. Few species demonstrate social learning, such as apes, elephants, and dolphins.

corvid fact: Mirror neuron are neurons with both sensory and muscular function, they allow an action to be recreated almost reflexively after observing it. Recent research has discovered mirror neurons in corvid's HVC, the area of the brain associated with learning vocalizations, but may explain other learned tasks that allow them to copy complex behavior observed by peers or other species.

corvid fact: Corvids are one of the few species to pass the mirror test, demonstrating a sense-of-self shared only with few primates and dolphins. The mirror test involves marking an animal without it being aware in a spot that cannot be seen without a mirror, presenting a mirror, and observing reaction. If the animal is aware it sees itself, it will touch the spot on its own body, perhaps a spot placed on a chimpanzee's forehead, or the throat of a Eurasian Magpie, the corvid most adept at passing the test.

corvid fact: Fledgelingsm after breeding season, will fly with their parents as they mob and accost predators, teaching them what is dangerous. Later, the young will help raise the next clutch or three of young from their parents, at first mimicking actions of feeding without food, then foraging and returning with food and feeding the hatchlings. They will venture out, assess the area and decide to make a nest of their own and mate, or return to the parents if circumstances aren't ideal and help raise another clutch.

corvid fact: Corvids can count. As well as counting student observers and not returning to their normal behavior after all of them had left the blind, multiple experiments have been run on captive crows. Containers with one though six dots on them were arranged with food under only one of them. The key, placed aside, had the same number of dots that the food bearing container had. Size, arrangement, and orientation of dots was changed, but the crow would always pick the correct container with the same number.

corvid fact: Adults will feed any open mouth in their nest, however, when fledgelings, they recognize them by voice. Not only can they differentiate their young from others, but identify them individually. Several families may visit one feeding area at the same time, parents catching food, and giving it to the young. All fledgelings will go towards the food, but the parent will only feed their own.

corvid fact: Corvids can effectively call each other by name. Each has their own unique call, even if only slightly different from another's. A crow's mate will mimic their unique call, and if possible, they will return immediately. Crows kept as pets will adopt a word their human says frequently and use it as their human's name, pronouncing it exactly the same as they do, as a call for them.

corvid fact: Crows in a flock share song elements, the more they share, the tighter their social bond is. If another crow is introduced in captivity to an existing group, it is shunned until it learns to mimic the particularities of that group, at which point it's accepted.

corvid fact: Crows respond to alarm calls differently depending on the intensity of the call. A slow backing caw likely means there's a predator at a distance, at which point other crows will investigate. A loud, quickly repeated alarm caw will cause those in the area to immediately take flight to mob and scold the predator.

corvid fact: Not only do crows do clever things, like dropping whelks to break the shell, but they do it efficiently. Averaging a drop height of 16 feet, sufficient to shatter the shell and not more, higher would have wasted foraging energy, and lower would have required a second drop. They would choose a flat spot to drop them onto so they'd not roll, then wash them in water to remove bits of shell and sand.

corvid fact: Corvids watch each other play, they do weird things like areial acrobatics, hang upside down from a branch looking like dorks, and bouncing up and down on a springy branch. This demonstrates some level of genetic fitness, and crows match up with their equal. Later, if a mate dies and a crow that's already raised young seeks a new mate, it is quite often someone their equal in rais young, as they observed their neighbors during their breeding seasons.

corvid fact: Mouth color in common ravens is both a function of age and social standing. From pink to mottled blue-black to black. A dominant raven can have a black mouth six months after fledging, while a highly subservient raven may remain mottled into adulthood. While social standing can swing significantly, there is no reversal in coloration. In a demonstration of dominance, ear feathers and pants are flared, as well as shoulders widened, resulting in wing tips crossing behind the back.

corvid fact: At only three weeks of age, ravens catch mosquitos and flies out of the air.

corvid fact: Unpaired ravens roost together in tens or hundreds, sharing information on carcases. Leaving an established roost in the morning for a new feeding area, the ravens will circle above the old roost for some time to collect everyone, before leaving for the new carcass, not to return the following night to the old roost but to establish another. While the ravens come and go as they please, they well coordinate new roosting locations. The roost is an effective information exchange center for food. This cooperation in unpaired ravens allows them to feed where there are established territorial pairs or other predators.

corvid fact: The American Crow, Corvus Brachyrhynchos, means short-billed crow, but it's not about the size, it's how they use it.

corvid fact: Young ravens learn what to eat by both observation and and experimentation. They'll follow their parents, who will initially find food and exclusively feed them. Later, they'll start to ignore them and make annoyed kek-kek calls when they're screaming for food while next to a food source. Anything their parents touch they'll investigate. Novel items, edible or otherwise, will always demand their attention, but soon ignored when found to be of no utility. An adult will scold if the juvenile tries to eat something known to be dangerous, passing knowledge to them and other juveniles that observed the act.

corvid fact: Some corvids, like pinyon jays, rooks, and jackdaws form dense colonies, unlike ravens. A breeding pair of ravens will claim a territory if available, which in some areas requires a current breeding pair to vacate due to death of the male. Nest spacing is regular, and seems to be a function of intolerance based on food supply, and not an innate, inflexible distance like in other animals. The more abundant a reliable food source is, the more tolerant pairs of ravens are to neighboring nests. Ravens can mate at age three, but in some areas first nesting isn't until age seven. A breeding pair may establish a nest for a season, then become vagrant once again, though still paired.

corvid fact: Collective nouns such as a murder of crows and unkindness of ravens, while correct in the Oxford English Dictionary, are strictly literary. Ornithologists don't use terms of venery. They're party poopers, and it also may imply behavior that isn't factual. Ravens will often feed in groups, or fly in groups for a day, but those groups are fluid, composed of vagrant juveniles, vagrant pairs, and territorial pairs. What's seen as a flock feeding on a carcass do not further necessarily associate with each other again, or even remain together for the rest of the day. While some pieces of the flock are a family unit that nest together, or a group of juvenile vagrants that roost together and move with food supply, a collection of ravens is just as meaningful as far as their association as a collection of humans at a grocery store.

corvid fact: Territorial raven pairs aren't necessarily spontaneously aggressive towards others. A mated pair of a territory will cooperate with a non-family member if it's seen to benefit them.

corvid fact: Juveniles not yet old enough to make still build nests, and pair up in their first year at time, though unable to lay eggs until their third year. Early mate selection and fruitless breeding attempts seems to be condition of mest they build, rather than condition of the female, to which some very surprised nest build males will attest.

corvid fact: A group of ravens will initially preen every other one, but as pairs develop, they're more selective in who preens whom, and how close they'll perch to one another. One will approach another, bend their head down so the other can preen the neck, and generally make a weird raveny soft muttering sound.

corvid fact: When the dominant male approaches a female, with his ears up and pants all ruffled, she'll not flee or fight like other males, but make a knocking sound, the sound of a powerful female, often followed by a vigorous tail feather wagging.

corvid fact: Dominance in a group is dynamic, removing a dominant male for some time will allow the next in line to take domnainance, which he will maintain if the previous is absent for some time. Once returned to the group, preening pairs are the same, though not having mated yet, though dominance does change. Dominance and pairing are largely unrelated.

corvid fact: Ravens are adept group hunters, in pairs or more. They've been observed multiple times preying on seal pups basking near their ice holes. One raven would cover the hole, while others attacked the seal.

corvid fact: Ravens are smarter than swans and know it, again hunting in pairs, one will taunt a swan trying to draw it from its delicious eggs, if unsuccessful initially it will feign injury knowing the swan will see it as an easy target and leave the eggs, at which point its companion raven will steal them while the other raven dragging a wing staying just out of reach of the swan draws it farther away.

corvid fact: Ravens are masterful observers. The zone-tailed hawk mimics turkey vultures, both in its style of soaring with V-shaped wing position, rocking from side to side, and soaring with turkey vultures. Trained ornithologists have a hard time identifying them at distance. A raven, however, identify them with an aggressive alert call at a great distance, a socially learned behavior from watching their peers or parents do the same.

corvid fact: Raven bills cannot penetrate the skin of a grey squirrel. They can use it to kill them by crushing bones on impact, but it lacks the penetrative power of a raptor's bill. Instead, they will eat it from the mouth, crushing bones and pulling out meat, slowly turning the squirrel skin inside-out as they do so.

corvid fact: Ravens flying with bills open, contrary to newspaper reports also accusing them of killing newborn cattle, is not an attack posture, but a sign of fright or overheating. 

corvid fact: Ravens will often wait a long time observing a carcass to ensure it's not alive or a thrat. Eventually, they'll get close enough and hop up and down in front of it like a lunatic to try to solicit a reaction, discriminating healthy from dead or mostly dead.

corvid fact: In the study of ravens, hatchlings have been swapped for much younger, older, or different numbers. While both parents may initially perch on the edge of the nest looking intently with one eye then the other, making irritated kek-kek calls, but not alarm calls, they do eventually and always adopt other chicks. They will not favor feeding their own over an adopted chick, only favor the most vociferous, as they do when they're all their own.

corvid fact: Similar to their adoption of chicks they know not to be their own, they will indiscriminately incubate eggs not their own. Ravens have been proven to be able to count, at least up to seven, accurately, so there is no doubting they're aware how many eggs they had before a sneaky ornithologist slipped in a chicken egg, another raven's, or a bright red painted chicken egg. While it may solicit the kek-kek call again if too obvious, they have not developed any egg rejection behavior. There are no known nest parasites that prey on ravens, such as cuckoos do on others by laing their eggs in their nests.

corvid fact: Ravens will nibble at unknown insects to taste them, then either spit them out or eat the rest. They don't attempt to eat bees, though they'll investigate dead ones. Ravens never before exposed to bees, when given drones, largely ignore them. They will initially eat a wasp, but they apparently taste bad. Bee and wasp mimicking flies they'll also try, and find delicious. Milkweed eating monarchs that are bitter are toyed with by ravens and pulled apart, but not eaten, though other butterflies are vigorously consumed.

corvid fact: A low ranked female, when paired with a dominant male, benefits from their relationship. By herself, she may be the last to bathe or feed, but her mate tolerates her above all others, even next order males. 

corvid fact: Ravens recognize their own species as well as crows. Dead ravens and crows were brought to captive ravens, who would make alarm calls and not touch the carcass. A headless crow was tried next, evoking an even more vigorous reaction, and aagain the carcass rotted in place. Finally, a skinned headless crow was presented without wings and legs, and consumed as any other carrion would be.

corvid fact: Ravens are hesitant to approach a carcass for feeding, and will allow eagles and crows to pick off meat for them, then give chase when they leave the carcass with it. The pursued bird drops the meat and the raven feeds on the carcass by proxy. They're exchanging a known risk, engaging another carrion eating animal, for the unknown risk of approaching a carcass.

corvid fact: If you're alone in the woods and a raven sees a mountain lion or bear, and you, that noise they make isn't meant to alert you to the threat of a dangerous predator getting closer and closer to you as it follows the raven in some strange act of cross-species altruism, they're trying to get it to kill you so they can feed on the leftovers. Make friends with ravens before they have you murdered. Mountain lions are ambush predators, attacks are commonly aborted if you let it know you see it.

corvid fact: Ravens have region, sex, and mate-specific calls. Like crows, they're accepted into a group or region once they learn the common calls there. Males learn and mimmic male calls to assert dominance, and females learn and mimmic female knocking calls for the same purposes. Mates will call eachother with their mate's name, mimmicking their specific call they make.

corvid fact: Male raven dominance isn't determined by testosterone line in some animals, but largely body size. Though they can fluff out, if one does this to challenge a current dominant male, the challenge is always returned. Since bluffing is ineffective, it's typical that only larger will challenge smaller. Mating displays, of both genders, are nearly the same as dominance displays. Low ranking ravens will refrain from mating displays in the presence of a dominant raven of the same gender, as it would simply be challenged and silenced. When a dominant pair is removed, behavior changes immediately.

corvid fact: Being a larer dominant raven is expensive, since feeding position is always on top of the carcass where they can be seen feeding, which is not the ideal position to actually get meat. They require significantly more meat being a larger animal, adding further survival resistance. For this reason, selection pressure curbs runaway growth in size, as they are the first to die when food is scarce.

corvid fact: Ravens are scared of any new thing. Initially as fledgelings they follow their parents and touch what they touch, and eat what they eat, solidifying in their minds known-safe items. When they're no longer juveniles, they become less curious, more cautious, and fearful of anything new. Experiments show they're also afraid of known safe items in new arrangements, perhaps a large pile of peanuts instead of one, a whole squirrel instead of pre-cut roadkill they were raised on, or cheetos dyed a different color. Each different arrangement is evaluated separately, just as an entirely new item would be.

corvid fact: Ravens become familiar with an item or experience and have certain expectations for its behavior. When these expectations are violated, they become fearful. A branch with a string tied to it moving it on a windless day will cause panic, a treat moving across the ground pulled by filament will induce equal panic. Much like people, they fear what they don't understand.

corvid fact: Given the choice of piles of food in an area with wolves, ravens invariably choose to feed at the same pile where wolves are present, being gut piles from human hunters, or prey brought down by the wolves. Ravens can remain afraid to approach a carcass for days, but when it's attended by wolves, they show no hesitation whatever. The ravens, because of their extreme vigilance and powers of observation, in return also warn the wolves well in advance of other animal approaching compared to the wolves' ability to detect another animal.

corvid fact: Ravens have been used as a tool to find poachers, as they will dip their wings when they see predator and prey in close proximity, anticipating a kill, and excitedly doing aerial acrobatics. They have observed humans, and have taken us as their wolf where a wolf is unavailable, equating us as much capable hunters, providing for them.

corvid fact: Ravens alter caching behavior when in the presence of others. If alone or a mated pair, meat is pulled off, stacked, and cached generally nearby, before eating their fill after enough caches. In the presence of other ravens, each piece is individually cached much farther away, out of sight. An accumulating pile may be robbed, and a close cache may be seen. If a dominant male keeps others from the carcass, they will frequently make nearby false caches, hiding sticks or bits of bark, like they would meat. These are generally investigated first by other ravens when he flies off for an actual cache, delaying their time on the carcass.

corvid fact: If a socialized group of ravens attacks an unfamiliar one, previously tolerant subservient ravens will join in the attack. Rarely, this will end in the victim's death, a reproach reserved for one seen robbing caches of the leader of the attack, or its familiar group, or countering an attack of the group with their own advance. None of the victim's actions against a single raven in the group would warrant such a final censure, but harm to the group is seen collectively, because of the social aspect of the group.

corvid fact: As demonstrated by experiments involving coating ravens in honey, which they detest, and flour, then a dung and water mixture, cleanliness is a tangential result of bathing, not the goal. Cooling in the summer is equally not a motivator of bathing, they bathe with just as much frequency just above freezing for there to be liquid water as they do at sweltering temperatures. Bathing for ravens is more related to play, or should a dominant raven not want to and a lower raven does, they will simply to deny the lower ranked raven, which may resume when the dominant is satisfied.

corvid fact: While ravens are the only passeriformes observed to carry anything with their feet, they prefer stacking objects to carry them. In the case with donuts, two are either wedged together with the top one sitting on edge in the hole of the lower one, or the raven will insert their beak through one and grasp the other. This has been replicated in experiments with other ravens nearby, pressuring the caching raven to carry more than one at a time. 

corvid fact: Like ingenious inventions of humans, raven behavior is sometimes a result of their exacting observation of a situation that happened upon, or accidental result of their actions producing an unintended but desirable result. Examples would be walnuts crushed by cars, deer bones, picked clean and of interest to no raven, paid on railroad tracks to expose the marrow.

corvid fact: When ravens are scared off their food, what they hold in their beak is always taken with them when they fly away. On the string test, when a piece of meat was suspended by three feet of string, each time it was retreived aand the raven scared off, it instinctively dropped the meat, a new behavior under novel circumstances. They also constantly returned and pulled up the string to get the meat, anticipating a delayed and not immediate reward.


sources: 
Mind of the Raven: Investigations and Adventures with Wolf-Birds by Heinrich, Bernd
Gifts of the Crow: How Perception, Emotion, and Thought Allow Smart Birds to Behave Like Humans by Marzluff Ph.D., John, Angell, Tony, John Marzluff
Bird Brains: The Intelligence of Crows, Ravens, Magpies, and Jays by Savage, Candace