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While most parrots only learn around 50 words, some African grey parrots have been known to learn hundreds. Einstein, a brilliant African grey parrot at the Knoxville Zoo in Tennessee, can say around 200 words.

Believed to be the first domesticated bird, pigeons were used for millennia to deliver messages, including important military information, and the outcome of the early Olympic games. Though non-avian mail delivery has become more popular over time, pigeons were used as recently as World War II to carry select messages.

Hummingbirds are incredibly lightweight. The average hummingbird is around 4 grams (one gram less than a nickel), while the smallest, the bee hummingbird, is closer to 1.6 grams, less than the weight of a penny. The largest member of the hummingbird family, meanwhile, is the aptly named giant hummingbird, which can get up to 24 grams—enormous for a hummingbird, but only equivalent to about a handful of loose change.

Native to New Zealand, kiwis are a bizarre, land-bound bird. Scientists, so mystified by the kiwi's strange properties—which include feathers that feel like hair, heavy bones filled with marrow, and nostrils on the tip of their nose (rather than on the base of their beak like most birds)—have sometimes called them "honorary mammals."

When they nap in groups, the ducks on the perimeter keep guard by sleeping with one eye open. While the other ducks sleep more deeply, those on the outside of the circle also keep one side of their brain awake, even as they doze, so that predators won’t be able to sneak up on them.

When owls catch larger animals (raccoons and rabbits, for instance), they tear them up into more manageable, bite-size pieces. But, they've also been known to simply swallow smaller animals, from insects to mice, whole. Owls then regurgitate pellets full of indigestible elements of their meal like animal bones and fur.

Cardinals (along with several other bird species) sometimes cover themselves in crushed or living ants, smearing them over their feathers, or allowing living ants to crawl on them. While scientists still aren't sure what the purpose of "anting" is, some believe the birds use the formic acid secreted during their ant bath to help get rid of lice and other parasites

Ostrich eyes are the largest of any animal that lives on land (though they can't rival some of the massive creatures that inhabit the depths of the sea). Approximately the size of a billiard ball, their eyes are actually bigger than their brains.

While ravens in the wild are unlikely to pick up human language, in captivity they can become quite talkative. Some ravens are even better than parrots at mimicking human speech, not to mention sounds from the human world like car engines revving or toilets flushing. In the wild, meanwhile, ravens sometimes imitate other animals, mimicking predators like wolves or foxes to attract them to tasty carcasses they're unable to break open on their own

Cardinals (along with several other bird species) sometimes cover themselves in crushed or living ants, smearing them over their feathers, or allowing living ants to crawl on them. While scientists still aren't sure what the purpose of "anting" is, some believe the birds use the formic acid secreted during their ant bath to help get rid of lice and other parasites.