Then I realized that the reason these homes were being built was to harvest the edible nests of the avian inhabitants to sell to China, and the piece became less charming. I loved the idea of a colorful spate of birdhouses being built all over Indonesia, for conservation or simply enjoyment. But for commerce – a kind of semi-parasitic home-stealing commerce – the birdhouses suddenly feel less appealing. A kind of Aesthetics of Joy used as deception, like a marketing bait-and-switch.

But regardless of the intention, there’s a joy-related insight here. It intrigues me that the builders of these houses use color to attract the birds, while when left to their own devices the swiftlets typically nest in caves. Is it that we are so inexorably attracted by bright color that we believe other species will be too? Or is there evidence that the birds prefer color, just like we do? Either answer makes a statement on the power of color to engage us and arouse our emotions.

If anything, birds may be even more sensitive to color than we are. Most birds are tetrachromats, meaning that they have four types of cone cells in their retinas, which are the cells that sense color. While humans have cones with red, green, and blue receptors, birds have a fourth cone that lets them see into the ultraviolet range. This means that birds may see colors we don’t even know exist!

Whether this brings them joy, we can only guess. But I guess it can’t hurt, if you’re building a birdhouse, to pull out all the stops (and the colors of the rainbow).

Grazie, Dario, for the link! And thanks to @markchangizi for first pointing out to me tetrachromacy in birds.