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Ask a Birder: Why are there more bird species now than 25 years ago?

May 28, 2025 by Kai Pflug 5 Comments

As you can see from the chart, the number of recognized bird species has increased from about 9,750 in 2000 to a bit more than 11,000 in 2024. Why?

Mostly, this is the result of species being split, rather than new species being discovered. Only about 5-10% of “new” species are the result of newly discovered birds, the rest are established species being split.

As ornithologists learn more about known bird species, they sometimes discover substantial differences within an established species. Newer tools and technologies, such as DNA analysis, as well as an added focus on bird behavior, are among the drivers of this process.

For example, in 2023, the Northern Goshawk was split into the Eurasian Goshawk and the American Goshawk, as their DNA shows substantial differences, and their vocalization is also different. Somewhat ironically, this is the reversal of a lumping of the two species about 80 years earlier.

There are also truly new species identified, typically 5 to 10 each year. For example, in 2022, the Meratus White-eye was formally described (as if the world needed more White-eyes). It had probably escaped ornithologists before, as it has only a small range and does not look all that different from some other species of white-eyes. The Inti Tanager is a more interesting example, a species discovery that required a new genus (i.e., it is not strongly related to the established species).

Purely based on the mathematical shape of the curve shown above, there will be about 15,000 bird species by 2100. Of course, most of us will be dead by then.

Sidenote: even though the rise in species makes the name of our website, 10,000 Birds, sound slightly outdated, we have no plans to change it.

Written by Kai Pflug
Kai has lived in Shanghai for 21 years. He only started birding after moving to China, so he is far more familiar with Chinese birds than the ones back in his native Germany. As a birder, he considers himself strictly average and tries to make up for it with photography, which he shares on a separate website. Alas, most of the photos are pretty average as well.He hopes that few clients of his consulting firm—focused on China’s chemical industry—ever find this blog, as it might raise questions about his professional priorities. Much of his time is spent either editing posts for 10,000 Birds or cleaning the litter boxes of his numerous indoor cats. He occasionally considers writing a piece comparing the two activities.