Most idioms contain at least elements of image and metaphor. Many are also rather like very condensed stories. The idiom “for the birds,” which is used in casual conversation to indicate an idea or object is completely useless, contains all three.
When something is labeled as being for the birds, the speaker is generally speaking with disgust. The idiom is a way of dismissing someone else’s idea or something more tangible, such as a project or plan, as worth little to nothing. The image these three words conjure is of something that has been thrown out the window like garbage, something that only birds would have any interest in.
That image carries a subtle subtext. Birds have long been viewed as simple creatures lacking any kind of intelligence. This is seen in another idiom, “birdbrains.” The implied message is that something that is interesting to birdbrained individuals lacks the necessary substance or importance to be of value to anyone with intelligence.
Something that is for the birds can be discarded out of hand, and no one is likely to object. To protest such a strongly expressed dismissal might suggest the protestor is a type of birdbrain as well. Rather than stand accused, most participants in such a conversation will step aside and allow the seemingly worthless notion or activity to be ignored, abandoned, and ultimately destroyed.
Historically, the phrase “for the birds” first became popular during World War II. It was based upon a cruder expression that conjured the image of birds feasting on cow or horse manure, hunting for seeds or undigested grasses. The expression became army slang for anything that was pointless, ridiculous, or simply without value to any but the most pathetic or least capable. In order to become incorporated into daily conversation as an expression, however, it needed to be cleaned up. The direct reference to manure was neatly eliminated, and the phrase shortened to the same three words that are used today.
While many English idioms have jumped the puddle and are widely used in England and other English-speaking countries, this is not one of them. Interestingly, the phrase enjoys its greatest popularity among American seniors and the very young. Perhaps this is because elders have used the expression since their own youth when it became popular and, as all new idioms do, seemed charged with meaning and fun. Youngsters like it simply because of the image it creates; they are equally fond of other idioms that contain animal life, such as “a fish out of water” or “a memory like an elephant.”