Like the majority of songbirds, American goldfinches use their nest only once — to raise one brood — and do not return to it after their young have fledged. This time of year, when leaves have fallen off of shrubs and trees, is a great time to try and locate where birds you saw all summer nested. Just as each species of bird has its own song, each species of bird builds a nest unlike those of other species. By noting the habitat in which it’s built, the material with which it was built, and the dimensions of a nest, it is often possible to determine the species of bird that constructed it. Female American goldfinches build a very neat nest composed of plant fibers, and line it with the down of cattails or thistles. The walls are quite thick, making it quite durable – the nest in the photograph even withstood the wind and rain that Irene delivered this fall. While it’s fun to hunt for nests, bear in mind that you need a federal permit to collect them.