The Story of Songbirds Is a Story of Sugar

Australia’s unique forests are the birthplace of birdsong. The plants there are drenched in sunlight and can readily mass-produce sugars through photosynthesis. But with few nutrients in the soil, they struggle to convert those sugars into leaves, seeds, and other tissues. They end up with excess, which they simply give away. Flowers overflow with nectar. Eucalyptus trees exude a sweet substance called manna from their bark. Even insects that suck plant sap are forced to excrete surplus sugars, in the form of liquids known as honeydew or lerp. As the biologist Tim Low once wrote, Australia has “forests that exude energy.”

In his book , Low reasoned that Australia’s birds have benefited from the island’s free-flowing that the largest group of birds—the oscines, or songbirds—originated in Australia before spreading worldwide. That group now contains about 5,000 of the 10,000 known bird species, including robins, cardinals, thrushes, sparrows, finches, jays, and starlings. All of these birds descended from an ancestor whose voice lilted through Australian trees and whose taste buds were tickled by sweet Australian nectar.