" " This lithograph from 1897 depicts a Northern raven, aka a common raven. It's much bigger than the American crow and has significant differences in its beak and wings. THEPALMER/Getty Images

It takes an eye for small details to be a good bird-watcher. And that's certainly the case for ravens and crows. Altogether, there are more than 30 species of crows and ravens worldwide. Many of these bear a passing resemblance to each other — so when you see one of the black birds, identifying it can present a real challenge. But their slight differences in size, anatomy, voice and behavior can help you tell them apart.

Now instead of comparing and contrasting the key traits of every single raven and crow species on Earth, we'll just focus on two well-known birds from North America: The common raven (Corvus corax) and the American crow (Corvus brachyrhynchos).



Let's begin with relative size. Common ravens are noticeably bigger; their wingspans can be 46 inches (or 1.16 meters) in total length while the distance between their beak tips and tail tips can reach 27 inches (68.5 centimeters). Contrast this with American crows, who've got 36-inch (0.9-meter) wingspans and grow to be just 20 inches (50.8 centimeters) long from end to end.

" " This lithograph from 1897 depicts an American crow. It's smaller than a raven and has gentler, fan-shaped tail feathers. THEPALMER/Getty Images

The wings themselves look different, too. At the tips you'll see the finger-like primary feathers that birds use to propel themselves through the air. Because ravens soar more often than crows do, they've got longer primaries. While we're on the subject of feathers, take a look at the tails. Crow tail feathers are arranged in the shape of a gently-curved, handheld fan. On the other hand, a raven's tail ends in a point, giving it a diamond-like appearance. Ravens also have shaggy feathers under their throats, which crows lack.

Bill shape is yet another point of dissimilarity: Unlike the straight-beaked American crow, the common raven has a curved, somewhat knife-like beak. Both birds have bristles (hair-like feathers) around the base of their mouths, but these are proportionately longer in ravens.

OK, time to move on to the vocal differences. You might be surprised to learn that both ravens and crows are considered songbirds. Neither sounds very pleasant, though. American crows make that jarring "caw-caw" noise (among other vocalizations) while common ravens emit a deep croaking sound.

When it comes to sociability, the two birds are light years apart. Crows amass themselves in large flocks — or "murders" — and may roost together at night in huge clusters of several hundred birds. Ravens are less gregarious, preferring to fly in pairs or in tight-knit family units. Their habitat preferences vary, as well. American crows generally favor wide open spaces while common ravens tend to hang out in forests.

Despite all the things that separate them, these birds share an impressive trait: high intelligence. American crows can learn to can recognize the faces of people who've tried to attack them while common ravens have shown both impulse control and active planning in lab experiments.