This week I was told of a fascinating Radiolab podcast - titled "The Beauty Puzzle". The podcast looks natural selection through a very interesting lens. I don't want to spoil the episode by recounting it here, but I will say that they spend several minutes discussing the Satin Bowerbird.
These amazing birds create an elaborate display, called a bower. There are many species of bowerbird, each constructing a bower with a different architecture. This one creates an avenue bower, consisting of sticks that basically form two walls, creating a pathway. The bird creates an expansive floor (called a platform) with sticks as well, and then decorates the scene with blue items.
Historically, the bird would have to work hard to find blue items in nature - perhaps flower petals or berries. These days, human trash, mainly in the form of plastic bottlecaps and straws, has filled the niche. But there are a couple blue/purple feathers in the mix as well.
Look closely and you'll see some yellow items. These are Sulphur-crested Cockatoo crest feathers. There were at least a dozen in the bower - it makes you wonder if it raids Cockatoo nest areas, or just has a keen ability to find these scattered about the wild?
When at the site, the bowerbird maintains a tidy bower. Sticks and leaves that fall or blow in are quickly removed. And time is spent putting any misplaced blue items back in their original spot.
Hard at work...
Like many birds, there are sub-species as well, and these sub species sometimes decorate differently, lining the platform with moss, or picking other colored objects.