The bird this week is the satin bowerbird.  It is so named because males build a bower, or little enclosure, as part of their mating display.    Male bowerbirds are uniformly black with purple eyes, females have bright blue eyes.  The way light refracts off their feathers makes them appear to be a bewitching iridescent dark blue.   Females and juveniles have a green speckled pattern that can make them hard to distinguish from a couple of different species of catbirds, the green and spotted catbird.  Satin bowerbirds are native to eastern and southeastern Australia,  and live in sclerophyll forests.  Sclerophyll plants are adapted to long periods of drought and heat, and have fat, waxy leaves placed closely together.  The most common example would be a pine tree, but there are lots of plants in lots of shapes adapted to this biome.  

The bowerbird builds a bower consisting of two walls out of sticks and gathers yellow, blue and shiny objects and scatters them about the area.  I read that these are the largest and most elaborate structures built by any animal except humans, but I also read recently about a network of termite mounds in South Africa that are tens of thousands of years old.  The bowers must be the biggest thing built by a single creature, since those mounds were built by untold billions of bugs.  Still, very impressive for a little bird.  Scientists theorize that the bird pick items that are blue because blue looks good with their plumage, although I also read a scholarly-adjacent source that said they like items that reflect ultraviolet light.  The idea of a bird accessorizing by coordinating colors is pretty great.  Because blue is a fairly rare color in nature and the birds prefer items that won’t fade or decay, they often incorporate blue pieces of refuse like bottlecaps and straws in their bowers.  That’s very clever, but honestly kind of sad as well.  In the absence of human trash, they will seek out blue flowers and feathers of other birds.  The satin bowerbird’s courtship ritual is pretty involved, so here’s an excerpt: 

“Recent research has shown that female mate choice takes place in three stages:

• Visits to the bowers, before nests have been built, while the males are absent
• Visits to the bowers, before nests have been built, while the males are present and displaying
• Visits to a selection of the bowers, after nests have been built, leading to copulation with (typically) a single male.

Experimental manipulations of the ornaments around the bowers have shown that the choices of young females (those in their first or second year of breeding) are mainly influenced by the appearance of the bowers, and hence by the first stage of this process. Older females, which are less affected by the threatening aspect of the males’ displays, make their choices more on the basis of the males’ dancing displays.”

I think its pretty amusing that young bowerbirds are more entranced by the bowers, while older ones are more able to see through the bells, whistles and tough guy aspects of the dance routine and assess the candidate more holistically.  Almost like human beings, who are easily distracted by superficial aspects of attractiveness when young, before (hopefully) mellowing out and looking for a compatible partner regardless of flash.  But I digress.  

Young male bowerbirds will sometimes destroy the bowers of males, and groups of young male bowerbirds will raid the bowers of older males and make off with their precious blue accoutrements.  

We’re almost there, folks.  Don’t let anyone steal your blue trinkets or your joy.

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