We are all familiar with the songbird or parrot species of bird. The word-speaking, sentence-forming birds that most would consider to be highly intelligent. But as most of us are aware, the ability to form sentences doesn't necessarily make one intelligent.

Corvidae, however, is truly a special species of bird. Corvids include birds such as crows, ravens, and magpies and they are also referred to as simply part of the crow family. And although they're not known for their linguistics, crows are highly intelligent.

The following is a compilation of studies conducted on crows that illustrates their exceptional intelligence.

First let's look at how crows have the ability to reason for cause and effect, as demonstrated by the video below.

In the video, a New Caledonian crow is tested by a stick emerging from a hole, then disappearing. In one scenario after the stick disappears back into the hole, a person emerges from behind the concealment. This tells the crow that the person was likely to be the one moving the stick-as sticks don't move on their own. In the next scenario the stick appears then disappears again, but this time, no one shows themselves. That in turn, made the crow very cautious and seemingly, very smart.

Crows also have the ability to understand water displacement. In a study using tubes, scientists floated a treat in a tube of water just out of reach of the crows. The crows then added stones to the water until the treat was attainable. Other tests showed that crows prefer to work smart and not hard, as the crows opted for tubes that required the least amount of effort.

"The crows' success rate was on a par with seven-year-old children," the researchers said.

Crows are capable of remembering faces and holding grudges. Not only do they remember, they also pass that knowledge along to other members of their community as stated in the following video.

Crows are known to hold funeral-like gatherings when one of their own dies. This is believed to occur for learning purposes. The crows are thought to communicate the cause of death to inform others of the dangers or perhaps discuss the communal hierarchy.  

The ability to solve puzzles is a trait that was believed to be present in only humans and apes, but as the following video shows, crows too are capable of the complex task.

Crows have also been observed making tools, exercising self control, and even playing. The following video went viral as it captures a crow that seems to be skiing. 

There's another member of the corvid family of birds that has been known to display high levels of intelligence; the raven. More to come on that.