The Empty Nest

I can always find something that is interesting to photograph at Mom and Dad's. This is a photograph of a now abandoned martin nest in a martin house. The houses are lowered each year after the brood has been raised. They'll remain at eye level until February when they are raised again to welcome the returning birds. What determines which pieces make it into the nest? Size, color, texture? Why that particular feather or that bit of string. I love nests.