They are made from color anodized aluminum.
They are very friendly and when they get together, they tend to chat quite a lot. Luckily when you wear them as earrings, there is a little separation so they are quieter!
We've had two batches of bluebirds nesting in our boxes this summer and both have yielded a few babies.
They don't look very blue yet, but then, I guess they need feathers to look blue!
They are useful birds to have in the vineyard - not just because they bring happiness (!), but also because they eat insects and thus keep the insect population down on the vines.
Take a look at the other birds that people have created as part of the bird a week challenge. The links are below: