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Tool use, memory, and complex rational thought

There are also specific examples of corvid cleverness. One carrion crow was documented cracking 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. A group of crows in England took turns lifting garbage bin lids while their companions collected food.

Members of the corvid family have been known to watch other birds, remember where they hide their food, then return once the owner leaves. Corvids also move their food around between hiding places to avoid thievery—but only if they have previously been thieves themselves (that is, 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.

The ability to hide food requires highly accurate spatial memories. Corvids have been recorded to recall their food's hiding places up to nine months later. It is suggested that vertical landmarks (like trees) are used to remember locations. There has also been evidence that California 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.

New Caledonian crows (Corvus moneduloides) are notable for their highly developed tool fabrication. They make angling tools of twigs and leaves trimmed into hooks, and then subsequently use the hooks to pull insect larvae from tree holes. Tools are engineered according to task, and apparently, also to learned preferences. Recent studies revealed abilities to solve complicated problems, which suggested high levels of innovation of a complex nature. Other corvids that have been observed using tools include: the American crow, blue jay, and green jay. Researchers have discovered that New Caledonian crows do not just use single objects as tools—they can also construct novel compound tools through assemblage of otherwise non-functional elements. 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.

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.