Rediscovery of disappeared species: Truly back from the brink?

Extinction is a focal issue among scientists, policy makers and the general public. Each year, numerous species which are thought to have disappeared are rediscovered. Yet, these rediscoveries remain on the brink of extinction.

Researchers from the National University of Singapore (NUS), University of Adelaide and Princeton University found that over the past 122 years, at least 351 species which are thought to have disappeared, have been rediscovered. The finding was derived from a first-ever such study conducted on the full extent of amphibian, bird and mammal species rediscoveries globally. The rediscovery of these once-missing amphibians, birds, and mammals occur mostly in the tropics.

However, despite many rediscoveries, 92 per cent of amphibians, 86 per cent of birds and 86 per cent of mammals are highly threatened, independent of how long they were missing or when they were rediscovered.

Under the current trends of widespread habitat loss, particularly in the tropics, most rediscovered species remain on the brink of extinction.

According to the lead researcher, Brett R. Scheffers, who is from the Department of Biological Sciences at NUS, most rediscovered species have small range size, which is the main driver in species extinction globally.

He said: "Rediscoveries, without aggressive conservation, likely represent the delayed extinction of doomed species and not the return of viable populations. In short, there is hope but we must step up rapid conservation efforts."

To make matters worse, the average number of years a species went missing is 61 years. This long duration makes conservation planning for missing species very difficult, particularly in areas that are of high value to humans. For instance, the protected areas that have been put aside for a particular species that has not been seen for numerous years could have be converted for agricultural use.

Findings from the study, which was published on PLoS One in July, are indicative of the limited knowledge of biological diversity in the poorly known tropics. Elaborating, Scheffers said: "We still have much to discover and these results indicate that it may not be too late for many species that have gone unseen for many years."

"We support and encourage more biodiversity surveys in the poorly known tropics. This is particularly important as many museums are experiencing shortened budgets or event budget cuts," Scheffers added.