To look upon the bower of a male bowerbird is to see something bizarrely familiar. These are not elaborate nests but rather architectural monuments whose sole purpose is to serve as a staging ground for mating displays. Males build and adorn these structures with precision and a sense of aesthetics. Because of this behavior, at least one species of bowerbird, the spotted bowerbird, can add another occupation to its resume - accidental gardener.
When a male finds a certain color he likes, he scours the landscape in search of these treasures. For many male bowerbirds, fruits offer a wide array of colors and textures of which they can add to their menagerie. Male spotted bowerbirds seem to have a fondness for the fruits of the potato bush (Solanum ellipticum). Their stark green hue contrasts nicely with the bower architecture.
When the fruits start to decompose, they no longer serve any purpose for the male bowerbird and he tosses them aside. Seeds begin to accumulate around the bower and after some time they will germinate. Researchers decided to investigate this relationship a bit further. What they found was pretty astounding.
They discovered that bush potato plants grew in higher numbers around bowers than they do at random locations throughout the forest. What's more, the fruits produced by bush potatoes growing near bowers were much greener than those of plants elsewhere. In effect, male spotted bowerbirds are not only cultivating the bush potato, they are also artificially selecting for improved coloration of its fruits.
To date, this is the only example of something other than a human cultivating a plant for reasons other than food. The similarities between human cultivation and bowerbird cultivation are mind blowing. Similar to human farmers, male bowerbirds clear the site of competing vegetation and remove the fuel load so as to minimize the risk of fire, all of which provides ideal habitat for germination. Though the male bowerbirds are not intentionally cultivating the bush potato, they have nonetheless entered into a mutualistic relationship in which the males get ready access to beautiful fruits and in return, the bush potato gets a nice, safe place to grow.
Photo Credit: University of Exeter
Further Reading:
http://www.sciencedirect.com/science/article/pii/S0960982212002084