the bower as channel stack

A satin bowerbird's bower is not a sculpture. It's a multi-channel display, and each channel runs on different physics.

Channel one: structure. Two parallel walls of vertically placed sticks, woven on a circular mat, the avenue between them up to two meters long. Some bowers are continuously maintained for thirty years, by successive males — like a building with no architect of record. Construction or refurbishment takes a male between a week and two months.

Channel two: paint. The male masticates plant pulp — sometimes charcoal, sometimes berries — mixes it with saliva, and applies the slurry to the inside walls. He uses his beak, and sometimes a wad of chewed bark held in the beak as a brush. That bark wad is one of the rare documented cases of a non-corvid bird using a tool. 93% of males in one study site painted; painting consumed about a quarter of total bower-time. The paint is not for the female to look at. During courtship visits, females nibble it. It is a chemosensory signal — a taste of the male, applied to the architecture so she encounters it as a property of the place.

Channel three: ornament. Blue. Blue flowers, blue feathers stolen from parrots, blue plastic bottle caps, blue pen lids, blue straws, blue clothes-pegs. Yellow and shiny also count, but blue is the project. Red objects are actively removed from the area, not merely not-collected. The male curates by addition AND subtraction. Mature males discriminate finer-grained blues than juveniles, so the palette refines with age.

Channel four: theft. Most blue ornaments at any given bower were stolen from another male's bower. Game theory work on this (satin and great bowerbirds both) shows that under most parameter ranges marauding-and-stealing is evolutionarily stable against guard-and-don't-disrupt. The most active thieves get stolen from most. The number of ornaments at a bower correlates with mating success precisely because it is an honest signal of the male's ability to defend the site against the same theft he himself practices.

Put it together: she walks into a structure her partner did not build alone (sticks reused across decades), painted with his own spit and chewed leaves (which she literally tastes from the wall), decorated with objects largely stolen from other suitors (whose absence from their bowers is the cost of his abundance at his), with red explicitly missing because he removed it, and blue ascendant because he is old enough to tell shades apart.

Each of those is a separate sense and a separate game. The male is presenting four arguments simultaneously, in four modalities, with four different epistemics — material persistence, chemical identity, curatorial taste, and competitive dominance — and the female is evaluating each on its own terms during one visit.

A sculpture is for the eye. A bower is for the whole organism, including the parts of the female's organism that decide before the eye does.