White Feathers: The Nesting Habits of Tree Swallows

I read White Feathers: The Nesting Habits of Tree Swallows by Bernd Heinrich. I like tree swallows. Their iridescent blue backs and skillful flying make them attractive birds to me. This author studied the tree swallows in his yard in Vermont for years. He kept track of their first appearances, their behavior, their mating, their nesting and the fledgling of the young swallows. He noticed that the swallows built their nests out of dry grass. Once the eggs (usually five) were laid and incubation begun the birds added feathers to the nest. The birds added more white or lighter colored feathers to the nest than darker feathers. He experimented with that. He threw feathers at birds and kept track of which ones the birds dived down to grab. He laid black feathers on a white tarp and white feathers on a black tarp. He got to the point where he could go outside during incubation time and the birds would approach him for his feathers. Most of the feathers went into the nests. Sometimes a bird would grab a feather from him, fly high in the sky, drop the feather, catch the feather, drop it again, catch it again and seem to entertain themselves with it. Tree swallows seem to prefer white feathers over black feathers. In one experiment he offered the swallows pieces of toilet paper cut into feathery strips. The birds like to toilet paper feathers too. Considering this book doesn't really have a plot, it was entertaining to a bird lover like me.