Brain Birds: Amazing Crows and Ravens

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Some crows in the southern hemisphere have white or gray markings, but all crows and ravens north of Mexico wear basic black. The plumage provides a passive solar overcoat, which absorbs the sun’s heat and helps the birds regulate their body temperature. Black also functions as surprisingly effective camouflage, not just at night for roosting birds, but also on sunny days when the dappled light amid leafy trees provides cover for shadowy crows on the move. Scientists say, too, that the birds’ iridescent ebony plumage helps them spot members of their own species from a distance, an important ability among social birds given to gathering in groups but not inclined to encountering enemy raptors.

Although crows and ravens apparently have no trouble telling one another apart, humans have a harder time discerning the distinctions. Size would seem to matter, since an average raven is far larger (2 to 4 pounds, with a wingspan up to 4 feet) than a correspondingly average crow (1 to 1½ pounds, with a wingspan up to 3 feet). But if you judge strictly by size, you can easily mistake a small raven for a large crow or vice versa.

Fortunately, there are more reliable criteria. If you get a close look, the presence or absence of the raven’s massive bill and distinctly shaggy throat and leg feathers can provide conclusive evidence. When gazing up at a flying is-it-a-crow-or-a-raven, check out the bird’s tail. A crow’s is squared off at the end, while a raven’s is distinctly wedge-shaped. Also, remember that ravens routinely soar like hawks, their widespread wings buoyed by airy thermals, while a crow seldom glides more than a few seconds.

Finally, listen to the bird’s calls. The crow’s trademark caw caw doesn’t remotely resemble the raven’s characteristic utterance, a deep guttural crrroak or raaaaahk.

Speaking of Intelligence

That crows and ravens are classified as songbirds may come as a surprise, but it is the presence of a voice box, or syrinx, rather than talent for melody that qualifies them. They use their vocal equipment to communicate with a large vocabulary of expressive calls for courting, gathering, warning and more. Ornithologists have identified as many as 24 crow calls and up to 64 distinct raven vocalizations. Among crows, most of the sounds are variations in pitch, intonation and repetitions of caw — from the loud caws! for alarm that are familiar to hikers, to a soft, affectionate caaaaaw for kin. Raven language, on the other hand, reaches well beyond the birds’ typical calls to include a repertoire of gurgles, rattles and bell-like notes — as well as a woodpeckerish knocking sound, “as of someone gently rapping, rapping.”

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