The Crow’s Path Blog

A few years ago I enclosed my front porch and built some cubbies to store my running shoes. It wasn't long after that the Carolina wrens discovered the cubbies and started building their nests tucked away in my shoes. This happened three years in a row, but the nests never had any eggs in them. While my shoes don't smell particularly nice, wrens don't have a well-developed sense of smell and don't seem to respond much to the scent of predators (and I don't think my shoes smell any worse than mink urine and feces: source). The behavior always struck me as odd - why go through all that trouble and put in such a big investment of energy to build a nest and not even use it? Here we look at some of the adaptive reasons a bird might build multiple nests.