Traditionally, humans have assumed that birds aren't exactly the smartest. When scientists looked into this, they found out that the general perception of bird intelligence over the years is blatantly wrong. Birds are actually quite intelligent animals, and they have a brain-to-body ratio that rivals great apes and cetaceans, some of the other most intelligent animals. Scientists also used to assume that most of the avian brain was used for instinctual behavior, rather than higher-level thinking and decision-making, which also turned out to be false.
Humans have many folds in their brains, which allows for more surface area, and therefore more higher-level thought, and it was discovered that birds also have more folds than previously thought. Because of this, birds use more of their brains for higher-level thinking and decision-making than instinctual behavior, which is more evidence for their intelligence level. Most birds are considered quite intelligent nowadays, but one group stands out: Corvidae.
Corvidae is a group of birds that includes crows, jays, ravens, magpies and other related species. They are some of the most intelligent birds, and they have been recorded as using tools to obtain food, which is a sign of higher-level thinking. Corvids are also known to remember people they have encountered before (there was an incident at University of Washington where some students angered some crows, and those crows harassed them every time they saw them until the students graduated).
The two most common species of corvid in Illinois are the American crow and the blue jay. Both species have been known to use tools, especially the American crow. The crow is also incredibly widespread, and various species of crow live in most places in the world. They thrive in urban environments, which is one reason they are so common around here — a large part of Illinois is suburban and the city of Chicago. Blue jays are also very good at adapting, and both jays and crows can be seen around backyard birdfeeders, capitalizing on the food that humans supply.
The most interesting thing about corvids is how they use tools. Crows in general have been known to use tools to unearth food, as well as jays, but one of the most interesting examples is the New Caledonian crow. These crows use sticks to poke at maggots in rotting trees, smart enough to realize that if the maggots become aggravated, their pincers close. When the maggots' pincers close, they grab onto the stick, and the crow can pull out an otherwise inaccessible bite of food. A species of crow in Japan has also been able to obtain inaccessible food — they drop nuts in the middle of traffic to crack them, using the cars' power to give them access to the nut meat inside. These crows have even figured out that it is safest to drop a nut in the crosswalk, and when the green light goes on, they can walk in the crosswalk to pick up their nut safely. It's not only crows who have this sort of ingenuity, though! Blue jays have been observed using strips of newspaper to help them pick up and carry food.
Birds are definitely smarter than you might think, whether they're corvids or not. So next time you're in your back yard and see a blue jay or crow, watch what it's doing and what it has in its mouth. You might see something that will surprise you!