Classifying species as extinct is an inherently inexact science, particularly in cases where they exist in small populations or extremely remote areas.
Consider the once ubiquitous, Australian yellow-spotted bell frog, one of seven frog species thought to have been wiped out in the 1970s by an African fungus.
By happenstance, a colony of 100 was found in a rural area of New South Wales last year, and their rediscovery announced on May 4. Dave Hunter, threatened species officer with the Department of Climate Change and Water:
To have found this species that hasn’t been seen for 30 years and that professional researchers thought was extinct is great. It gives us a lot of hope that a lot of other species that we thought were extinct aren’t actually extinct – we just haven’t found them.”
The case of the yellow-spotted bell frog is one example of why scientists are hesitant to declare species extinct even when they haven’t been observed for decades. Such reluctance, and the fact that so few of Earth’s species have been cataloged, results in more “new” species being identified each year than are declared extinct — even as human activity is known to have increased historical rates of extinctions.
In the last decade, three new species of frog have been discovered in the Kimberley,” he said, referring to a northern region of Western Australia state. “I know of two more in the Northern Territory which haven’t even yet been described … one of the specimens is sitting here on my desk looking at me.”
In terms of survival, whether a once thriving species is classified as extinct or reduced to a population of 100 is almost a distinction without difference – except in cases where rediscovery and conservation efforts can help species regain a foothold. According to the Sydney Morning Herald, six tadpoles have been taken to the Taronga Zoo to establish a breeding program.
If it has a predisposition to being resistant to this fungus, as opposed to having site attributes resulting in resistance, that will afford it much greater protection when we start putting it elsewhere,” Dr Hunter said.
The yellow-spotted bell frog is the second Australian frog species have reappeared in the last few years.
As encouraging as these rediscoveries are, Earth’s biodiversity remains in peril. the International Union for Conservation of Nature (IUCN) estimates that as many as 17,300 species are under threat of extinction, including one-in-five mammals, one-in-eight birds, one-in-three amphibians, and one-in-four corals.
