Is interesting how some birds interact with man made things. Have seen a Magpie play with a tennis ball, rolling it back and forth. Have also seen a Pied Currawong pulling the fuzz off a tennis ball no doubt for nesting material. Have seen a Raven flying with a golf ball before as well. Then can't miss out the Satin Bowerbird, the things that they gather up are endless as long as they are mainly blue, but not always. Probably only scratching the surface with what they do, have seen quite a few different things on David Attenborough docos.