Many species are known to have vanished from the Earth over the last few hundred years. Over the same period, many new species have been discovered. Logically, there must be some species that went extinct without ever being discovered. How can we estimate these “undetected extinctions”? In a paper just published in Conservation Biology, we provide a new method for doing so. Our method is more flexible than previous methods because it does not rely on strong assumptions about extinction and detection rates being constant over time. Our method can be applied at both global and national levels.

We apply the new method to Singapore’s bird fauna over the last 200 years and estimate that, in addition to the 58 known extinctions out of 195 total known bird species, a further 9.6 species have gone extinct without ever being discovered (with a 95% confidence interval of [3.4, 19.8]).

Chisholm R.A., Giam X., Sadanandan K.R., Fung T. & Rheindt F.E. (2016). A robust non-parametric method for quantifying undetected extinctions. Conservation Biology.

The Scarlet-rumped Trogon (Harpactes duvaucelii) could conceivably be one of Singapore’s undetected extinctions: it is common in forests in nearby Johor but was never observed in Singapore itself (Photo credit: David Tan).