Scientific classification Class AVES Order PASSERIFORMES Family CORVIDAE Sub-family CORVINAE Genera and species CORVUS CORAX CORAX – the raven CORVUS CORONE CORONE – the black crow CORVUS FRUGILENUS FRUGILENUS – the rook COLEUS MONEDULA SPERMOLOGUS – the Jackdaw
The raven and its relatives (crows, jackdaws, jays) are the biggest and most robust representatives of the Order Passeriformes. Although it is difficult for us to imagine them alongside the nightingale or the wren, nonetheless they are part of the same order. Resilient birds, capable of surviving extremely cold temperatures, the Corvidae are widely spread throughout the northern hemisphere. Good fliers, having mostly black plumage, these birds are particularly intelligent. Their intelligence was observed even in Antiquity, and recent studies regarding the behaviour of ravens evidenced amazing faculties which until now were known only in relation to some of the non-human primates: fabrication of tools, using manoeuvres for deceiving adversaries, caution and even the capacity to count. Studies are only in an early stage and, in many respects, the behaviour of these extraordinary birds is still mysterious and exciting. The Corvidae in literature and artAre ravens bad, ominous birds which must be killed, persecuted, banished away to the mountains, far away from human settlements?The black plumage, its entire austere appearance, but especially the speed of their arrival on battlegrounds covered with corpses won them the reputation of mortuary birds, harbingers of death. This is the way the raven was perceived especially by romantic poets in the 19th century, and even later at the beginning of the 20th century, until after the First World War, by the Symbolist poets. George Bacovia (1881-1957) evokes the raven in many poems. Some of the best known lines by Bacovia about ravens can be found in Twilight: “The ravens pass – oh, the «Ravens»/ of the Poet Tradem -/ And they flow at dusk/ Over the frozen town.” This is maybe an homage paid to another poet, the wretched Traian Demetrescu (1866-1896), who died of tuberculosis when he was only 30 years old. Ravens and crows often appear in his poems (“Autumn crows fly in flocks, flocks of crows/ Leaving, mortuary crows shrieking ominously”), but the line evoked by Bacovia belongs to an epitaph written by the Oltenian poet who used to sign his name by using the first three letters of his name and surname: Tradem. The poet said: “And ravens will fly over my forgotten grave/ And it will snow.” But besides the provincial sadness of the great Romanian poets, for whom the crows and the ravens are elements of scenery which cannot miss from the depiction of old towns overwhelmed by the dampness of the autumn which governs people’s melancholies, the raven is the hero of some of the greatest universal poems. One of the most famous still remains The Raven by the American poet Edgar Allan Poe (1809-1849), which he wrote over more than a decade (1832-1845), publishing no less that 16 versions. This poem even gives its title to the last volume published by Poe in 1845 (The Raven and other Poems). Charles Baudelaire’s translation of 1 March 1853, a great admirer of the American writer, then the translation of Stéphane Mallarmé, published in 1875, opened the road for a wide recognition of the great musical poem, together with its obsessive refrain “Nevermore”. We should add that Mallarmé’s version from 1875 (Richard Leschide Publishing House, Paris) was illustrated with Edouard Manet’s lithography works, and later on Paul Gauguin engraved a portrait of the French poet together with a raven (1891). However, besides the image of the raven in modern poetry and art, there is an entire mythology in which this black bird occupies a central part. The symbolism surrounding the raven is often contradictory, due to its widespread habitat. Due to its colour, its eerie croak and its scavenging nature it is considered in many places as a bad omen bird. In the Indian Mahabharata ravens are the messengers of death, while in Japan they are considered divine messengers and symbols of filial devotion. In ancient China the raven was a solar bird, in ancient Greece the raven was the bird of the god Apollo, and in Celtic legends it had a prophetic role. In German mythology the raven accompanies the great Wotan, and in Scandinavian mythology we can find two ravens perched on Odin’s throne, one named Hugin, representing the spirit, and the other Munin, representing memory, both symbols of creation in perfect balance with the two wolves which symbolised destruction. A raven was also found on Noah’s ark, which was sent, as the Bible says, in the Book of Genesis, to discover if the waters had started receding. The comments related to its behaviour are not wholly favourable, but it was eventually “forgiven” because it helped the prophet Elijah by feeding him when he fled to the desert, as he was hiding from the vengeance of Queen Jezebel. The region where the raven was most revered and respected is however North America. For many of the North American tribes, especially for those on the north-western coast of the Pacific, the raven is the central divine figure, primordial hero and demiurge which organised the world, disseminated civilisation and culture, created the sun and placed it in the sky, brought fire down on earth. Native Americans had numerous stories dedicated to the adventures of the raven. Revered as the founder of some tribes, its image was displayed on top of totem poles (“At the beginning, the Raven made us, everything around us and the totem poles as well”).A Haida myth of the Native Americans from Queen Charlotte Islands tells of how the raven found a giant sea shell on a beach, after the waters of the great flood pulled back. The shell was filled with tiny scared creatures. The raven managed to convince them to leave the shell and start discovering the world: these creatures were in fact the first people.In other tales the raven stole the sun, brought the first salmon, the first fruit and other such presents for people. The raven as seen by zoologistsThe Corvidae family has nearly 100 species, its largest representative being the large raven, Corvus corax, which inhabits a wide area encompassing the entire northern region of the planet. Zoologists believe that there are at least 8 raven sub-species inhabiting this region, Corvus corax being the one which inhabits the northern and central part of Europe, especially the mountain areas. Other sub-species can be found in North America, Asia and the north of Africa. As regards its size, the raven is often compared with a buzzard (Buteo) one of the common predacious birds in Europe. Ravens are powerful birds, measuring 51 up to 64 cm, having long wings, triangular shaped-tip whose wingspan can reach almost 130 cm. Its beak is massive, bulky, measuring 7-8 cm, slightly convex, the upper side being curved downward like a real hook. Its black feet and long sharp claws remind us of predacious birds. Its plumage is also completely black, ‘funeral black’, as Bacovia would describe it, with steel-like metal blue reflexes. The feathers around its neck are longer and thinner and because they are erectile, they often look like a strange bristled beard. They change their plumage each year starting from July until October. There is no sexual dimorphism, male and female ravens being exactly alike. Its eyes – which clearly demonstrate a live intelligence – have a black-brownish iris, surrounded by an almost white ring. Flight The raven is an excellent flyer; it does not care about storms, being capable of travelling considerable distances. But it is especially a masterful acrobat having an extremely diverse repertoire: loopings, swirls, flight dropping, floating in mid-air against the wind, floating on the back with its wings spread out, then coming back to a rather normal position and then surprising again its observers with another incredible trick. All these dance moves seem to be a continuous play and not a mating ritual, because they occur throughout the year, not only during the mating season.During mating season it flies together with its mate and their acrobatics are really stunning, their performance being quite remarkable when the two birds clench their claws together, one of them floating upside-down on its back.Ravens float easily, skilfully, using hot ascending wind thermals which carry them to very high altitudes. In the Alps ravens have been seen at altitudes of up to 3800 m. They are not bothered by cold, no matter how penetrating, and together with the ptarmigans (Lagopus) they are the only birds which can live during the winter beyond 80˚ northern latitude.In straight-line flight the ample movement of its wings cut through the air with a rhythmical deaf sound which can be heard from the ground. When it walks the raven is proud in conduct, solemn-like, shaking its head after each step and dangling its body from right to left every time it croaks.
“Family” lifeRavens are monogamous birds, the male and female mating for life. They do not become close very fast, as it happens with many birds, but only after knowing each other throughout a year. Only during their second year together do they consolidate their relationship and the partnership is established for life. The territory, once established, will not change with time.The actual mating is preceded by a spectacular nuptial parade that takes place first in the air – the partners flying together – and then on the ground. The first part is dedicated to extraordinary aerial acrobatics executed by the two partners, but the ground ceremony is also a special one. The male comes close to the female in successive leaps, then takes a “bow” before the female and huffs its throat feathers, spreads its wings and stretches its tail, then they caress each other and touch each other’s beaks.The big black bird is very quick to mate and to prepare its nest, as compared with other birds, starting with January. Only the common crossbill (Loxia curvirostra) with its strange beak, with curved, criss-crossed tips, is faster to mate than the raven.The raven builds its nest in areas inaccessible to predators: crevices in rocky cliffs or on top of tall trees. The old nests are rebuilt year after year and they can measure up to 1 m in diameter. Their base is made up of a twine of branches over which the birds add moss, lichens, dried grass and animal fur. Usually, the nests can be found between 800 m and 1500 m altitude, the raven clearly preferring mountain areas, although it can be found at lower altitudes, on the hillside or even in the lowlands. The female lays four up to six big eggs, one egg a-day, (3-4 cm in diameter, weighing 25-30 g), green or blue with brown spots which it hatches for 20 days. Throughout this period she is fed by the male, which remains permanently around the nest. The chicks hatch bald and blind and are fed by both their parents. They leave the nest after 5-6 weeks, around May, and they continue to share the same territory as their parents until autumn, accompanying them in searching for food. When autumn comes they join flocks of young birds, which can have a much as 200-300 birds, which move from one place to another. They reach sexual maturity only during their second year, and then they leave their parents' territory and start looking for a partner and for their own territory. Vocal repertoire and habits Besides the rough, grave sounds which it usually makes, that “caw” or “croak”, there are several other inflexions and tones which can vary from one bird to another. Some sounds are either monosyllabic, or a series of sounds, others are sharp and melancholic shrieks which resemble the sounds made by a xylophone. The raven also “sings” a mixture of various low intensity sounds, which basically resemble the sound made by a man gargling. But beyond its own croaks and shrieks, this bird is a terrific imitator. It can become accustomed to the presence of humans, if fed by them, and it is capable of reproducing words or entire sentences in various languages with a perfect intonation.Although it is permanently distrustful and extremely prudent, the raven is nevertheless curious by nature and attracted by shiny objects which it does not hesitate to steal and bring to its nest. Besides, a raven with a ring in its beak was portrayed on John Hunyadi’s coat of arms, the father of Matthias Corvinus, the king of Hungary. DietThe raven's diet is extremely diversified. They eat small live animals, mice, moles, hedgehogs, lizards, small birds and even rabbits. It also eats snails and insects, or even seeds and fruit. If they come near areas inhabited by men, they often frequent garbage dumps.Ravens are therefore omnivorous, but they clearly prefer a carnivorous diet, that is why ravens are present on battle grounds, feeding on the dead bodies. Throughout the year the raven is a scavenger bird, but the most abundant period for this type of food is spring, when they can find many dead animals, either because of the avalanches, or else due to the lack of food towards the end of winter. During periods when food is abundant ravens save pieces of meat and fat, most often hiding it in crevices in the rocks or inside holes which they dig in the ground, as evidenced by Eric Dragesco’s research (Germany, March 1985).
Ravens don’t rush to devour a corpse but they carefully observe it for a few days and only then do they start eating. Like many other birds, ravens eliminate regularly non-digested matters as ingluvies. Representatives of the "black people"Out of the 100 sub-species of the Corvidae family, incorporating two sub-families, Corvinae and Garrulinae, 12 species live in Romania. Besides the raven and the rook, there are also magpies (Pica pica), jays (Garrulus glandarius), but also spotted nutcrackers (Nucifraga cryocatactes), alpine coughs with yellow beaks and red feet (Pyrrhocorax graculus). There is also another type of jackdaw (Corvus monedula) with two sub-species – spermologus and soemmerringii, and if the carrion crow (Corvus corone corone) is rather rare in our country, hooded crows (Corvus corone cornix) are instead very numerous. In the 1950’s Romanian authorities took drastic measures for the eradication of ravens and crows, birds which were considered pests, harmful to small game and also to crops (which was not entirely true), obliging hunters to shoot a certain number of corvidae. This also happened throughout Europe. Results were soon observed; the birds became quite rare and now are considered to be on the verge of extinction. After they were added to the list of protected species their numbers increased. An extremely intelligent bird Ever since antiquity the raven and the crow were considered intelligent birds. Let us just remember that the great fabulist Aesop (who lived 2600 years ago), in order to illustrate the fact that necessity is the mother of all inventions, presented the story of a thirsty crow which not being able to reach the water in a jug filled the jug with stones, thus elevating the liquid so it could drink it. Many years later, in 1668, La Fontaine in his fable The raven and the fox however presented the raven as a conceited, stupid bird which the fox tricks into dropping the cheese from its beak. Stories about the cleverness and cunningness of the corvidae are very numerous and until a few decades ago were considered true legends. Recent ethological studies (made by biologist specialised in studying animal behaviour) have demonstrated that these legends have a true background. Even the story told by Tobias Dantzig in his book Number: The Language of Science written in 1930, which suggests the possibility that ravens have elementary knowledge about numbers, proved to be real. His raven was capable of distinguishing the variation in the number of hunters, either 4 or 5, who were skulking in a shelter waiting for its return to the nest; nowadays we know for sure that these birds know how to count at least up to 7. Stories about crows stealing from fishermen by pulling on the thread of the fishing rod, immediately after the sinker goes down, a sign that the fish bit the lure, are also true. There is also another story about a captive crow that filled a teacup with water and poured it over its food to moisten it in order to be easier to swallow.If Konrad Lorenz amazed us with his accounts about the behaviour of a flock of jackdaws (Corvus monedula), published in his book King Solomon's Ring, the data we have available today, based on experiments, testify to the really extraordinary intelligence of these birds which, to a greater extent, exceeds what we know about non-human primates.The neocortex of mammals associated with cognitive processes (memory, reason or associated intelligence) is mostly developed in the case of anthropoid apes; birds however do not have a neocortex, but the anterior side of the raven’s brain, for example, is more developed than with most other birds. It seems that this superior development ensures complex behaviours and associations, such as the manufacturing of tools which facilitate the gathering of food. It is true that there are other animals as well which use tools: twigs or cactus thorns used by the Galapagos woodpecker finch (Geospiza pallida) to pull out insect larvae from plant stems, the lures used by herons to attract fish, the rocks used by chimps to break nuts. But, nevertheless, all these are surpassed by the deeds of a raven species from New Caledonia (Corvus moneduloides). It uses tools in order to pull out insect larvae or spiders hidden inside plant stems, being capable of manufacturing from hard and fibrous Pandanus leaves three types of tools: a broad one, a narrow one and the third one shaped like a stair, actually a succession of steps combining the solidity of the broad tool with the precision of the narrow one. It is remarkable that the “handle” of these three tools is always wider, and the tip, the useful part, is always narrower. Sometimes after toiling for a long time, the bird makes a hook on one side which can have more versions as well. A team of researchers from the Oxford University (2002) working with a Caledonian raven in captivity noticed that the bird, without any previous training, is capable of bending a wire and use it in order to pull out its food container from a pipe.
Transmission of knowledgeIt is likely that young Caledonian ravens learn how to make tools by observing their parents in action. Caledonian ravens are social birds which live in small family groups. As such knowledge is transmitted from mature to young individuals.Two Austrian researchers, Johannes Fritz and Kurt Kotrschal, discovered that a “teacher” raven can teach other ravens how to open a can of food. If they don’t have such a “teacher”, each raven tries to open the can in its own way.Recent research performed also in Austria, on the alpine chough (Pyrrhocorax graculus) testifies to the existence of an actual language used by these birds to communicate amongst themselves. Sonograms revealed the existence of 18 different phonemes. Other experiments performed by researchers from Cambridge University regarding the intelligence of the corvidae have proved the existence of certain strategies for the protection of food deposits in the case of a species of jay (Aphelocoma californica). The California jay buries food provisions for the winter and if during this operation it is seen by another bird which might steal its food, the jay comes back later and changes the location of its “storage room”.What is the cause of the development of these amazing cognitive capacities in corvidae, not encountered in other species of birds? It seems that two factors had a considerable contribution in this respect. The fact that both ravens and their relatives – jackdaws, crows etc. – are omnivorous birds: the search for food presupposes a lot of time and the result of this search depends to a great extent on the abilities of the bird. This seems to be the key to the evolution of intelligence, the way of life, as survival and reproduction require an adaptive behaviour.Other researchers believe that the complex social organisation is the main reason for the evolution of cognitive activities. In support of this thesis they bring as arguments recent studies which confirm the importance of the association between cognitive capacities and the complexity of social life.But the fascinating life of ravens still has many undiscovered or even mysterious aspects. Let’s just hope that they will soon be discovered!Article published in Terra Magazin
Zoologist, museographer, science historian, Alexandru Marinescu has worked for 42 years at the Grigore Antipa National Natural History Museum. Chief of department, organiser of numerous exhibitions, he published more than 500 works and articles and 11 books. He was one of the members of the Romanian expedition to the Indonesian Archipelago (1992, as a marine biologist and diver, and he participated to the Canadian expedition on the Saint Laurent River. He also worked on board the famous ship Calypso, together with Jacques Yves Cousteau, to whom he dedicated two books (1980 and 1999). He is a member of the International Council of Museums and he was for eight years president of the National Romanian Committee. He is the vice-president of the Romanian Committee for the History and Philosophy of Science with the Romanian Academy, and at the same time a deputy chief-editor of the publication issued by this committee, the prestigious magazine Noesis. He has been a long-time contributor to the Romanian Television, the oldest member of the team that produces the weekly “Tele-enciclopedia” show. He realised the anthology Calatorii extraordinare (Extraordinary Journeys) (2001) for CD PRESS, translated Denis Buican’s book Epopeea lumii vii (Epics of the Living World), and regularly publishes articles in Terra Magazin. Translated by Anca Dumitriu
by Alexandru Marinescu
