American crows aren't viewed favorably by many people. Maybe it's because they have long been viewed as an omen of death, or because they are sometimes associated with witchcraft. Or maybe it's because crows were among the thousands of birds used in Alfred Hitchcock's horror classic "The Birds."

There's quite a bit to appreciate about these birds, however. To start, like many birds, they help disperse seeds because their diet includes seeds and fruit. Crows are also a boon to us because they are scavengers and will eat animal carcasses, helping keep the environment clean, according to Animal Diversity Web.

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Besides these important environmental roles, crows create an aura of mystery for people. Maybe it's their all-black appearance or because a group of crows is called a murder of crows.

No matter your opinion of these birds, there's probably a lot you don't know.

They are extremely intelligent

Birds in the corvid family, which includes crows, ravens and jays, are known for their intelligence, and crows in particular are extremely intelligent birds. Some of the latest research on the intelligence of corvids, including crows, indicates they may be about as smart as gorillas and chimpanzees, according to National Geographic.

Crows have very large brains for an animal their size, National Geographic reports. While crows and chimps have different brain structures, they are both able to use imagination and anticipation to solve problems. 

The reason crows are so intelligent may be because of their highly social nature. Living in a large group is complicated for animals, including humans, so many of the most social wildlife species, such as chimpanzees, gorillas and dolphins, are also among the most intelligent.  

They hold funerals

Since crows are very social birds, part of their socializing involves holding what amounts to a funeral for their dead. When a crow finds a dead crow, it will call out to others, and they will all gather around the dead bird, the National Audubon Society reports. When they gather, they often make a lot of noise as they communicate with one another.

While we associate funerals with grieving and mourning, for crows they likely are more about information gathering. The crows come together in a "funeral" to try to determine if there are risks near where the crow died, according to National Geographic. This way they can determine if an area is safe or needs to be avoided. 

They can hold a grudge, but they also give gifts

Crows can recognize humans, which is remarkable in and of itself, but beyond that, they also know which humans are good humans and bad humans based on their previous experiences with them. Those bad humans they might hold grudges against, while good humans might receive gifts.

Crows' ability to recognize humans was put to the test by wildlife biologists who conducted an experiment using rubber masks. One mask was used on "dangerous" humans, while a different mask was used on humans who behaved neutrally, NPR reports. The "dangerous" humans trapped and banded crows, which can be a scary experience for a bird, even if they aren't hurt. The people wearing the neutral mask did not engage with the crows. To test the theory that crows can recognize faces, the "dangerous" humans then returned to the area where the birds had been trapped and banded, and, sure enough, the crows behaved aggressively toward them, dive bombing them and angrily calling out. Meanwhile, they mostly ignored the neutral humans.

If you get on a crow's good side instead of bad side, you might just receive a gift from it. Many cases have been documented of crows leaving gifts for humans they like. Oftentimes, the recipients of these gifts are humans that have left food out for the crows, and the gifts can include rocks, bones and lost objects like earrings and keys, according to the National Audubon Society.

They gather in huge flocks

Because they are sociable, crows like to be around other crows. At night, they roost in communal groups, and they usually return to the same roost night after night, according to the Washington Department of Fish and Wildlife. During the day, they break into smaller groups that spread out to feed before returning to their communal roost at night. This practice helps keep the crows safe and warm, and it also allows them to share information and find breeding partners. 

In the winter, flocks of crows can become massive, with some flocks numbering as many as 2 million birds, Cornell Lab reports. In some areas, crows have used the same winter roosting spots for more than 100 years, with new generations of crows roosting in the same spot as crows from many generations before. These large winter flocks can be loud and messy and can cause conflict with humans when they develop in populated areas.

They are clever when it comes to their food

We've established that crows are extremely intelligent, and they are able to use their intelligence to make tools. These tools might seem rudimentary by human standards, but crows have been observed breaking pine cones into pieces and dropping the pieces onto people climbing trees to protect their nests; using wood to fashion a stick to put in a hole in search of food; and using a "cup" to carry water, the Cornell Lab of Ornithology reports.

As skilled as these tool tricks may seem, there is another crow species, the New Caledonian crow, that is even more adept at making and using tools. These crows, which live in New Caledonia, a group of islands between Australia and New Zealand, have shown the ability to make and use tools, planning up to three moves ahead, National Geographic reports. Their ability to plan their moves to accomplish something was tested in an experiment in which they had to learn a sequence of steps to help them solve a puzzle in exchange for food. 

New Caledonian crows, which are related to our more familiar American crows and other corvids, are regarded as among the smartest of animals. They are known to create spears and hooks from wood and other objects so they can catch grubs and other food. They also have been seen dropping rocks into containers filled with water so they can displace the water to get at food, National Geographic reports.