Dear Straight Dope:
I recently purchased a new bird feeder, filled it with (what else?) bird food, and hung it in a tree where there had never been a bird feeder before. Within an hour it was crowded with birds munching happily. My question: How did the birds find the bird feeder? Have they evolved to the point where they actually recognize a bird feeder from the air? Can they smell the food? Does one bird find the feeder, then communicate its location to the other birds by some secret tweeting code? Do they hang out at the bird feeder store and follow the bird feeders to their new home? This will forever puzzle me until you uncover the truth.
There’s nothing particularly mysterious about this. Birds are just very good at finding food. Being small and warm-blooded, they have to consume a relatively large amount of food each day, and need to be efficient.
Small seed-eating birds probably cruise the neighborhood regularly in search of food, both individually and as members of flocks. It’s quite likely they recognize a standard bird feeder as a highly concentrated source of food, not because they have evolved to do so, but on the basis of experience with similar feeders in the past, either in your neighborhood or elsewhere.
Most birds have a poor sense of smell, so they find feeders mainly by vision. Upon finding a food source too big for a single individual to consume, some birds will call to mates, or sometimes to flock mates, to alert them to its presence. But not all calls at a food source are altruistic. Once a few birds have gathered, they may fight over access to the food, especially if only a few good perches are available. The threat calls they give may inform other birds in the area that something worth fighting for has turned up, and attract them.
Send questions to Cecil via email@example.com.
STAFF REPORTS ARE WRITTEN BY THE STRAIGHT DOPE SCIENCE ADVISORY BOARD, CECIL'S ONLINE AUXILIARY. THOUGH THE SDSAB DOES ITS BEST, THESE COLUMNS ARE EDITED BY ED ZOTTI, NOT CECIL, SO ACCURACYWISE YOU'D BETTER KEEP YOUR FINGERS CROSSED.