Dear Word Detective: In a recent boating magazine, I read an explanation of the phrase “as the crow flies.” I had always thought this to be straightforward, meaning overland, as a bird would fly, as opposed to by the road. According to this magazine, however, it arose from an extraordinary practice by sailors at some unexplained time in the past: sailors would keep caged crows in anticipation of fog. When fog became dense, they would release the bird, its flight being unerringly to the nearest land, so they could take a bearing off the crow’s flight to shore. This seems wildly improbable, but since it is print, it must be true, right? — Sam Glasscock.
Oh boy. Take a seat, Sam. I’m afraid I have some bad news. That “if it’s in print it’s trustworthy” business hasn’t been true since pretty much the day after the invention of movable type. In fact, I’ve come to the conclusion that stories about word and phrase origins found in popular magazines are usually untrue, sometimes hilariously so. Sadly, even books devoted to word origins, including some from reputable publishers, often repeat stories debunked years ago. I can only assume that the authors of such works are so taken with a particularly charming and “neat” story about a word or phrase that they decide that it must be true and forgo any sort of actual research.
But even by the low standards of the mass media, the story you read is a humdinger. As usual in such cases, there is a suspicious lack of detail; as you note, this practice supposedly took place “at some unexplained time in the past.” 200 B.C.? 1924? Add to that the fact that the story does not make even superficial sense. If the sailors were lost in fog, wouldn’t the crow immediately disappear into the fog? And what if the shortest course to the shore turned out to be onto a reef that would sink the ship? The bird wouldn’t care. In fact, given how smart crows are, it might take revenge for its captivity by directing the ship onto the nearest rocks. Trust me, a crow is a lousy substitute for charts and a compass, both of which were in common use in 1800 when “as the crow flies” first appeared in print.
The logic behind “as the crow flies” meaning “in a direct line overland” is simply that crows are fairly large, highly visible (and very noisy) birds that generally fly directly to their source of food (as opposed to swallows, for instance, which feed by swooping around and catching insects). In an age before human flight, the sight of a crow gliding smoothly through the sky to its destination must have inspired envy in earthbound travelers, who had to deal with natural obstacles (mountains, rivers, etc.) in their path. “As the crow flies” was thus the best way to explain that the distance specified was direct (“The distance … is upwards of twenty-five miles as the crow flies,” 1810), as opposed to the route a plodding human would have to take, which would likely be much longer.