Songbirds Came From Australia

Northern cardinal, singing (photo from Wikimedia Commons)

31 August 2022

Songbirds (Oscines) are the majority of the world’s birds as you can see circled on the supertree below. In August 2016 we found out that all of them originated in Australia. Here’s how it happened.

Phylogenomic supertree of birds, a clockwise spiral from oldest to newest, marked with Australian origins (image from MDPI, July 2019)

The world was a very different place during the Oligocene 35 million years ago. For one thing there was a big gap between Australia and Asia and songbirds’ ancestors could not leave Australia.

Geography of the Oligocene from Wikimedia Commons

Then about 25 million years ago a land bridge formed when tectonic activity forced a patch of islands called Wallacea to the ocean’s surface. Wallacea, now part of Indonesia, bridged the gap and was the first step on the songbirds’ journey. (Ancient Wallacea in yellow below.)

Map of ancient Wallacea from Wikimedia Commons

They made the journey in flying steps, reaching the Western Hemisphere before Eurasia:

  1. Australia (label C below)
  2. Wallacea, an island group in Indonesia (label D)
  3. Southeast Asia and India (label E)
  4. Sub-Saharan Africa (label F)
  5. The Americas (label G)
Steps of songbird radiation from Australasia (map from “Tectonic collision and uplift of Wallacea triggered the global songbird radiation, Nature Communications, 30 Aug 2016) annotation: Wallacea “D” is circled in white

Like this…

Some songbirds were so successful that their DNA is found at each stop in living species across the world. Corvids are one such group.

Common raven, Yosemite (photo from Wikimedia Commons)

Others, like waxwings (Bombycillidae), have few DNA traces to show the path they took. Waxwings’ living DNA relatives are found only in Wallacea, North America and northern Eurasia.

Cedar waxwing (photo by Cris Hamilton)

Learn more about songbirds’ amazing journey in these articles:

(blank world map from Wikimedia Commons. photo and remaining maps are credited in the captions, click on the links to see the originals)

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