Tree Swallows almost always use feathers as nest construction material. I've found as many as a dozen in one nest. The feathers are usually white. I see this in the nest boxes I tend at a golf course in Wayzata. I have no idea where the birds find the feathers. Farms, farms with chickens, are few here, even in the western parts of the county. I used Trumpeter Swans feathers for these photos, feathers found near a Carver County pond owned by a friend. (The swans come to open water in the winter. )The swallow here struggled with the feathers, failing with larger, succeeding with smaller, fluffy feathers. This male Tree Swallow had encouragement but no help from its mate. Researchers say the feathers keep nests warmer. So, why don't other cavity-nesting birds, like chickadees and woodpeckers, do the same?