Australia has more native bird species than almost anywhere else. What led to this explosion of diversity?

An Opalton grasswren. Barry Baker

When you went out today, did you see any birds? A galah perhaps, or a crow?

If you did, there’s a decent chance the bird you saw lives nowhere but Australia. Out of about 850 species found in Australia, 45% are “endemic”, which means they’re unique to Australia. The only other country with more endemic species is Indonesia.