Getting the blues to get the girls

I came across this yesterday while bushwalking in the North Rocks area. It's a satin bower bird's bower.

The male bird builds this thing, which is not a nest, but a place to do ritual dances around, and then collects blue things. He's extremely fond of blue things.

And presumably, so are the females. The more blue things he's collected and showing off, the better his chances of getting the girl.

Presumably bright blue things used to be rare and precious. Now there's lots of them and they're nearly all plastic bottle tops, straws, or suchlike. The magic must still work though.

More on them here: https://en.wikipedia.org/wiki/Satin_bowerbird

We were wondering why blue is the chosen colour. Maybe it's the relative rarity of the colour in nature. A bit like we're often attracted to gold? There again, the male bird himself has a blue sheen, and bright blue eyes. We didn't see him yesterday, but here's a picture from the Wikipedia article.

                                          Photo: Joseph C Boone