Neurobiologists from the University of Tubingen in Germany have demonstrated that corvids - a family of birds including ravens, crows and magpies - are highly intelligent, something scientists have long suspected.

Prior to their research, behavioral scientists have nicknamed corvids "feathered primates" because of their ability to make and use tools and plan their social behavior according to what other members of their group do.

"Many functions are realized differently in birds because a long evolutionary history separates us from these direct descendants of the dinosaurs," neurobiologist Lena Veit said in a statement. "This means that bird brains can show us an alternative solution out of how intelligent behavior is produced with a different anatomy."

Turbingen researchers are the first to investigate the brain physiology of the crow's intelligent behavior. During their study, they trained crows to carry out memory tests on a computer.

The birds were shown an image and had to remember it. Shortly after being shown the image, the crows had to use their beaks to select one of the two test images on a touch screen. One of the images is identical to the first image they were shown, the other one is different.

Sometimes the rule of the game was to select the same image, and sometimes it was to select the different one.

The crows were able to carry out both tasks and to switch between them as appropriate. That demonstrates a high level of concentration and mental flexibility which few animal species can manage - and which is an effort even for humans.

While the crows performed these tests, researchers observed neuronal activity in the brain region associated with the highest levels of cognition in birds.

"One group of nerve cells responded exclusively when the crows had to choose the same image -- while another group of cells always responded when they were operating on the 'different image' rule," according to a press release. "By observing this cell activity, the researchers were often able to predict which rule the crow was following even before it made its choice."

According to a press release, crows and primates have different brains, but the cells regulating decision-making are very similar. They represent a general principle which has re-emerged throughout the history of evolution.

"Just as we can draw valid conclusions on aerodynamics from a comparison of the very differently constructed wings of birds and bats, here we are able to draw conclusions about how the brain works by investigating the functional similarities and differences of the relevant brain areas in avian and mammalian brains," professor Andreas Nieder said.