They're birds, but don't call them bird brains.
Ravens and crows might be just as clever as chimpanzees despite their tiny brains, scientists in Europe have found.
When it comes to solving a simple food retrieval task, previous research has linked an animal's chance of success to the size of its brain.
It held true for apes and a number of other species, including birds, but researchers in Sweden, Germany and the UK noticed corvid birds -- such as crows, jackdaws, ravens and magpies -- weren't looked at.
After teaching them to extract food from the ends of an opaque cylinder, they presented the birds with food trapped inside transparent tubes -- the same test used on the apes.
Despite being able to see the food, the birds generally knew to go for the uncovered ends. The ravens got it every time, and the other birds' performance was "very close to 100 percent comparable to bonobos and gorillas".
"This shows that bird brains are quite efficient, despite having a smaller absolute brain size," says Can Kabadayi, doctoral student in cognitive science.
"As indicated by the study, there might be other factors apart from absolute brain size that are important for intelligence, such as neuronal density."
Something for birds to crow about.