tolik k mym sympatiim ke kockam (smrdi a jsou blby!), zatimco napriklad krkavci chovani pro nataceni filmu jsou na urovni cca 8leteho dite, coz kocka nikdy nezvladne.
Intelligence
See also: Avian intelligence
The brain-to-body weight ratios of corvid brains are among the largest in birds, equal to that of most great apes and cetaceans, and only slightly lower than a human.[6] Their intelligence is boosted by the long growing period of the young. By remaining with the parents, the young have more opportunities to learn necessary skills. Since most corvids are cooperative brooders, their young can learn from different members of the group.[7]
When compared to dogs and cats in an experiment testing the ability to seek out food according to three-dimensional clues, corvids out-performed the mammals.[24] A meta-analysis testing how often birds invented new ways to acquire food in the wild found corvids to be the most innovative birds.[25] A 2004 review suggests that their cognitive abilities are on par with those of great apes.[26] Despite structural differences, the brains of corvids and great apes both evolved the ability to make geometrical measurements.
Corvid ingenuity is represented through their feeding skills, memorization abilities, use of tools, and group behaviour. Living in large social groups has long been connected with high cognitive ability. To live in a large group, a member must be able to recognize individuals and track the social position and foraging of other members over time. Members must also be able to distinguish between sex, age, reproductive status, and dominance, and to update this information constantly. It might be that social complexity corresponds to their high cognition.[27]
The Eurasian Magpie is one of the few non-mammal species known to be able to recognize itself in a mirror test.[28]
There are also specific examples of corvid cleverness. One Carrion Crow was documented to crack nuts by placing them on a crosswalk, letting the passing cars crack the shell, waiting for the light to turn red, and then safely retrieving the contents.[29] A group of crows in England took turns lifting garbage bin lids while their companions collected food.[citation needed]
Members of the corvid family have been known to watch other birds, remember where they hide their food, then return once the owner leaves.[citation needed] Corvids also move their food around between hiding places to avoid thievery, but only if they have previously been thieves themselves i.e., they remember previous relevant social contexts, use their own experience of having been a thief to predict the behavior of a pilferer, and can determine the safest course to protect their caches from being pilfered. Studies to assess similar cognitive abilities in apes have been inconclusive.[30]
The ability to hide food requires highly accurate spatial memories. Corvids have been recorded to recall their food's hiding place up to nine months later. It is suggested that vertical landmarks (like trees) are used to remember locations. There has also been evidence that Western Scrub Jays, which store perishable foods, not only remember where they stored their food, but for how long. This has been compared to episodic memory, previously thought unique to humans.[7]
New Caledonian Crows (Corvus moneduloides) are notable for their highly developed tool fabrication. They make angling tools of twigs and leaves trimmed into hooks, then use the hooks to pull insect larvae from tree holes. Tools are engineered according to task and apparently also to learned preference. Recent studies revealed abilities to solve complicated problems, which suggests high level of innovation of a complex nature.[31] Other corvids that have been observed using tools include the American Crow, Blue Jay and Green Jay. Diversity in tool design among corvids suggests cultural variation. Again, great apes are the only other animals known to use tools in such a fashion.[7]
Clark's Nutcrackers and Jackdaws were compared in a 2002 study based on geometric rule learning. The corvids, along with a domestic pigeon, had to locate a target between two landmarks, while distances and landmarks were altered. The nutcrackers were more accurate in their searches than the jackdaws and pigeons.[32]
The scarecrow is an archetypal scare tactic in the agricultural business. However, due to corvids' quick wit, scarecrows are soon ignored and used as perches. Despite farmers' efforts to rid themselves of corvid pests, their attempts have only expanded corvid territories and strengthened their numbers.[16]
Current systematics places corvids, based on physical characteristics other than their brains (the most developed of birds), in the lower middle of the passerines[vague], contrary to earlier teleological classifications as "highest" songbirds due to their intelligence.[9] As per one observer:
During the 19th century there arose the belief that these were the 'most advanced' birds, based upon the belief that Darwinian evolution brings 'progress'. In such a classification the 'most intelligent' of birds were listed last reflecting their position 'atop the pyramid'. Modern biologists reject the concept of hierarchical 'progress' in evolution [...].
—[8]
The other major group of highly intelligent birds of the order Psittaciformes (which includes 'true' parrots, cockatoos and New Zealand parrots) is not closely related to corvids.