In Birds’ Pursuit of Love, New Plant Life Blooms - Male bowerbirds cultivate plants, a new study reports, though their gardening work appears to be unintentional.
The birds, found in Australia and Papua New Guinea, are named for the extravagant structures they build to woo females. As part of their courting strategy, they decorate these bowers with fruits, and the seeds of these fruits germinate. This results in new plants of the species Solanum ellipticum, also known as the potato bush.
“On average you find about 40 plants where bowers are,” eight times as many as at random sites, said Joah R. Madden, an evolutionary biologist at the University of Exeter in England.
The findings appear in the journal Current Biology.
The researchers found that the birds were not picking areas with high plant concentrations to build their bowers, since the plants began to appear after their arrival.
“These plants are arriving after the bowerbirds,” Dr. Madden said. “In a sense the male is cultivating them.”
It appears to be an excellent symbiotic relationship, he said. When the birds build their bowers, they clear the area around them, creating ideal growing conditions for the plants.
“When we look around bowers, only 30 percent is covered with grass, shrubs, compared to random sites, where’s there about 50 percent,” Dr. Madden said.
And male bowerbirds surrounded by more plants had more success with mating.
Curiously, males seem to cultivate a duller, grayer version of the fruit; fruits grown farther from bowers were a more yellowish green.
Dr. Madden isn’t sure why. “Presumably because that’s what the female wants,” he said. ( nytimes.com )
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