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What the sources say

Common RavenCorvus corax

Every figure, record and mechanism on the Common Raven profile was written from a source, and this is the working table behind it: 52 claims checked word for word against these sources. The left column is what the page says. The right column is the source's own words, copied, not paraphrased; a ... marks a cut and[brackets] an insertion. Open any source and check it yourself.

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Source
01

Animal Diversity Web, University of Michigan

Corvus corax (common raven). Animal Diversity Web, University of Michigan.

The page saysThe Biggest Perching Bird
The source saysThese are the largest passerines.Note: heading; ADW's family-tree label reads "Order Passeriformes perching birds"
The page saysis usually set apart from other crows by its large size
The source saysThey are generally distinguished from other Corvus species by their large sizeNote: ADW's taxonomy line glosses Genus Corvus as "crows"
The page saysAdults reach up to 69 centimeters long
The source saysAdults reach up to 69 cm in length
The page saysAnimal Diversity Web lists them as the largest of the passerines, the perching birds
The source saysThese are the largest passerines.Note: ADW's family-tree label reads "Order Passeriformes perching birds"
The page saysAt Home Almost Anywhere but Rainforest
The source saysthese ravens can be found in most types of habitats except for rainforestsNote: heading
The page saysCommon ravens range from northern Europe, the British Isles, mostly coastal Greenland and Iceland east across Asia to the Pacific, south to the Himalayas, the Middle East, northwest Africa and the Canary Islands, and through North and Central America
The source saysfound in northern Europe, the British Isles, Greenland (mainly coastal areas), Iceland, northern Scandinavia, east through central Asia to the Pacific Ocean and south to the Himalayas and northwestern India, Iranian region and near east, northwestern Africa and the Canary Islands, and North and Central America as far south as NicaraguaNote: "mostly coastal" keeps "mainly coastal areas"; "Middle East" for "Iranian region and near east". Southern limit left out: Smithsonian says "far south to the mountains of South America", ADW says Nicaragua
The page saysThey prefer open country such as treeless tundra, seacoasts, rocky cliffs, mountain forests, plains and deserts, but turn up in most habitat types except rainforest
The source saysCommon ravens prefer open landscapes, such as treeless tundra, seacoasts, open riverbanks, rocky cliffs, mountain forests, plains, deserts, and scrubby woodlands. However, these ravens can be found in most types of habitats except for rainforests.
The page saysRavens are mainly scavengers, but they also eat small mammals, birds, reptiles, amphibians and insects, and round things out with grains, acorns, fruit and buds
The source saysCommon ravens are mainly scavengers. They eat a wide array of animal foods, including arthropods, amphibians, small mammals, birds, reptiles, and carrion ... Vegetable foods include grains, acorns, fruits, and buds.Note: insects are among ADW's arthropods, and ADW says they eat the insects that feed on carrion
The page saysStomach analyses show their diet is mostly mammal flesh, followed by insects and birds
The source saysStomach analyses show that the diet is made up primarily of mammalian flesh, followed by insects and birds.Note: "mostly" for "primarily"
The page saysRavens hide food of all kinds, from nuts and bones to eggs and meat, in caches
The source sayswill store foods of all kinds, including nuts, bones, eggs, and meat
The page saysincluding alarm calls, chase calls and calls for advertising territories
The source saysThere are alarm calls, comfort sounds, chase calls, and calls designed for advertising territories.
The page saysThe oversized scavenger
The source saysThese are the largest passerines.Note: tagline; "mainly scavengers" in the same account
The page saysMainly carrion and other scavenged food, plus small mammals, birds, reptiles, amphibians, insects, grains, acorns and fruit
The source saysCommon ravens are mainly scavengers. They eat a wide array of animal foods, including arthropods, amphibians, small mammals, birds, reptiles, and carrion ... Vegetable foods include grains, acorns, fruits, and buds.Note: stats.diet
The page saysTundra, seacoasts, rocky cliffs, mountain forests, plains and deserts
The source sayssuch as treeless tundra, seacoasts, open riverbanks, rocky cliffs, mountain forests, plains, deserts, and scrubby woodlandsNote: stats.habitat, terrain clause
The page saysacross Europe, Asia, North Africa and North and Central America
The source saysfound in northern Europe, the British Isles, Greenland (mainly coastal areas), Iceland, northern Scandinavia, east through central Asia to the Pacific Ocean and south to the Himalayas and northwestern India, Iranian region and near east, northwestern Africa and the Canary Islands, and North and Central America as far south as NicaraguaNote: stats.habitat, range clause; continents only, so the Greenland hedge does not arise
The page saysfrom alarm calls to chase calls and territorial calls
The source saysThere are alarm calls, comfort sounds, chase calls, and calls designed for advertising territories.Note: vibe.reason

Source
02

Smithsonian's National Zoo and Conservation Biology Institute

Common raven. Smithsonian's National Zoo and Conservation Biology Institute.

The page saysweigh between 0.7 and 1.6 kilograms
The source saysbetween 1 and 3.5 pounds (0.7 to 1.6 kilograms.)Note: ADW's 689 to 1625 grams agrees
The page saysRavens have more than 30 different vocalizations on record
The source saysMore than 30 different vocalizations have been recordedNote: ADW gives 15 to 33 categories; the Smithsonian's current page is preferred
The page saysin human care they can mimic simple sounds, even human speech
The source saysin human care, they can mimic simple sounds--even human speechNote: ADW says mimicry "has not been unambiguously documented"; the Smithsonian's current page is preferred and its "in human care" scope kept
The page saysa wild raven can live 10 to 15 years
The source saysIn the wild, ravens can live to between 10 to 15 years.Note: faq 4
The page saysone in human care could possibly reach 40 or 50
The source saysIn human care, it is possible these birds could live to between 40 or 50 years of age.Note: faq 4
The page saysMore than 30 different vocalizations on record
The source saysMore than 30 different vocalizations have been recordedNote: vibe.reason
The page saystags: tool-user
The source saysThey have been known to use tools to obtain food
The page saystags: woodland
The source saysRavens are extremely common in woodlands

Source
03

BirdFacts, British Trust for Ornithology

Raven. BirdFacts, British Trust for Ornithology.

The page saysThe oldest raven in the British Trust for Ornithology's ringing records survived 17 years, 11 months and 15 days
The source saysMaximum age from a ringed bird 17 years, 11 months, 15 days (set in 2000)

Source
04

The IUCN Red List of Threatened Species 2025

Corvus corax. The IUCN Red List of Threatened Species 2025: e.T22706068A281841771.

The page saysLeast Concern
The source saysIUCN Red List category: Least Concern (LC)Note: stats.conservationStatus, read through GBIF's copy of the Red List per docs/fact-check.md

Source
05

Heinrich & Pepper 1998

Heinrich & Pepper (1998). Influence of competitors on caching behaviour in the common raven, Corvus corax. Animal Behaviour.

The page saysHiding a Meal From a Thief
The source saysravens not only recovered their own caches, but also routinely recovered the caches they saw others makeNote: heading
The page saysIn one study of four captive ravens, a small amount of food that any one bird could have carried off in several trips got all four caching sooner and faster
The source saysWhen four birds were simultaneously given a small amount of food, which any one bird by itself could easily remove in several trips, all four birds decreased the latency to begin caching and increased caching speed.Note: "four captive nonbreeders" in the same abstract
The page saysWhen there was only enough food for one bird to control, caching was greatly delayed
The source sayswhen the four birds were given only enough food for a single individual to control, caching was greatly delayed
The page saysGiven space to get out of their rivals' sight, the birds cached farther from the food
The source saysravens instead cached further from the food source, provided they had space into which they could escape from the sight of the competitors
The page sayscaches food out of rivals' sight
The source saysravens instead cached further from the food source, provided they had space into which they could escape from the sight of the competitorsNote: tagline and stats.superpower clause
The page saysIn one study, captive ravens recovered their own caches and also routinely recovered the ones they had seen other ravens make
The source saysravens not only recovered their own caches, but also routinely recovered the caches they saw others makeNote: faq 1; captive: "four captive nonbreeders"
The page saysWhen a bird could not get out of a rival's view, it put off caching or hid its food while the rival was busy
The source saysWhen escape from competitor vigilance was not possible, common ravens delayed caching and/or hid food when the competitor was preoccupied.Note: faq 1

Source
06

Bugnyar, Reber & Buckner 2016

Bugnyar, Reber & Buckner (2016). Ravens attribute visual access to unseen competitors. Nature Communications.

The page saysGuarding Against an Unseen Rival
The source sayswe find that ravens guard their caches against discovery in response to the sounds of conspecifics when a peephole is open but not when it is closedNote: blockquote lead-in
The page saysravens hid food while a hidden loudspeaker played sounds recorded from a rival raven, though the room next door was empty
The source saysthe observation room was empty, and a hidden loudspeaker was used to play a series of sounds that were recorded from a competitor raven
The page saysThey guarded their caches against discovery when a peephole in the wall between the rooms was open, but not when it was shut
The source sayswe find that ravens guard their caches against discovery in response to the sounds of conspecifics when a peephole is open but not when it is closedNote: the wall: "two rooms separated by a wooden wall", each window with "a peephole drilled into its cover"
The page saysThe researchers suggest ravens can infer the possibility of being seen from their own experience
The source saysOur results suggest that ravens can generalize from their own perceptual experience to infer the possibility of being seen
The page saysguards the stash when it might be seen
The source saysOur results suggest that ravens can generalize from their own perceptual experience to infer the possibility of being seenNote: tagline clause
The page saysguards the stash when an unseen rival might be watching
The source saysravens Corvus corax take into account the visual access of others, even when they cannot see a conspecificNote: stats.superpower clause
The page saysRavens in one study were first trained to use a peephole to spy on human-made caches in the next room
The source sayseach raven was individually trained to use one of the peepholes to observe and recover human-made caches in the adjacent roomNote: faq 2
The page saysthey treated the test like caching in full view of another raven, as though an audible competitor could potentially see their caches
The source saysWe show that ravens treat the test condition like the observed condition, indicating that they can generalize from their own experience using the peephole as a pilferer and predict that audible competitors could potentially see their cachesNote: faq 2; the observed condition had the windows to the adjacent room containing conspecifics open

Source
07

Massen, Ritter & Bugnyar 2015

Massen, Ritter & Bugnyar (2015). Tolerance and reward equity predict cooperation in ravens (Corvus corax). Scientific Reports.

The page saysTeamwork With Conditions Attached
The source saysceased cooperation when being cheated uponNote: heading
The page saysWithout any training, nine captive ravens spontaneously cooperated
The source sayswithout training, nine ravens spontaneously cooperated in a loose-string taskNote: captive: "Subjects were 9 sub-adult common ravens (6 males, 3 females) of our captive colony"
The page saystwo birds had to pull both ends of a string at the same moment to drag a food platform within reach
The source saysonly if both ends were simultaneously pulled, the feeding platform would move towards the aviary
The page saysPulling one end alone unthreaded the string and left the platform where it was
The source saysIf only one end of the string would be pulled, the string would become unthreaded and the platform would stay stationary.
The page saysThe more tolerant two birds were of each other, the more successfully they cooperated
The source saysravens' cooperative success increased with increasing inter-individual tolerance levels
The page saysA bird whose partner had taken both rewards on the last successful try was less likely to pull on the next one
The source saysbirds were significantly less likely to pull when they received no reward in the previous successful cooperation trialNote: a cheat is defined in the paper as "taking both rewards instead of sharing"
The page saysis less willing to pull its weight after a partner cheats
The source saysbirds were significantly less likely to pull when they received no reward in the previous successful cooperation trialNote: tagline clause; cheating is "taking both rewards instead of sharing"
The page saysis less willing to pull after a partner cheats
The source saysbirds were significantly less likely to pull when they received no reward in the previous successful cooperation trialNote: stats.superpower clause
The page saysThey can, without any training
The source sayswithout training, nine ravens spontaneously cooperated in a loose-string taskNote: faq 3
The page saystolerance between birds predicted cooperative success both in pairs set up by the researchers and in a group where each raven could choose its partner
The source saysravens' cooperative success increased with increasing inter-individual tolerance levels. Importantly, we found this in both a forced dyadic setting, and in a group setting where individuals had an open choice to cooperate with whomeverNote: faq 3
The page saysA bird that grabbed both rewards did not become fairer afterwards: it became even more likely to cheat again
The source saysWe found that after cheating the cheater did not become more fair to get back the motivation of its partner, but instead became even more likely to cheat againNote: faq 3

How the table was made: a writer drafted the profile from these sources and logged each claim with its quote, a reviewer with nothing but this table checked every sentence said no more than its quote, and a script confirmed each quote appears word for word in the source. The method is in the site'sAbout page.