The rapid loss of species signals an acceleration of the natural process of extinction. While species naturally disappear over geological time, the current rate is estimated to be far higher than the historical baseline. This decline in global biodiversity is recognized by scientists as a crisis impacting ecosystems. Species losses officially noted in any given year, such as 2019, serve as stark indicators of this ongoing trend and highlight the urgent need to understand the mechanisms driving the disappearance of life forms.
The Process of Declaring a Species Extinct
The declaration that a species is extinct is a rigorous process overseen largely by the International Union for Conservation of Nature (IUCN). The organization defines a species as “Extinct” only when there is no reasonable doubt that the last individual has died. This determination requires extensive field surveys conducted throughout the species’ known and expected habitat over a period appropriate to its life cycle.
This strict methodology means a species declared extinct in a specific year, like 2019, may have actually vanished decades earlier. A separate category, “Extinct in the Wild,” is used when a species only survives in captivity or as a population far outside its original range, such as in a zoo or conservation facility. The time lag between a species’ functional disappearance and its official declaration reflects the scientific community’s reluctance to give up hope until all search efforts have been exhausted.
Confirmed Species Losses of 2019
The year 2019 saw the official confirmation of several notable species losses. One of the most significant was the Bramble Cay melomys (Melomys rubicola), a small rodent endemic to a single, low-lying island in the Torres Strait of Australia. This particular loss gained attention because it was recognized as the first mammal extinction directly attributable to human-caused climate change, specifically due to repeated ocean inundation of its habitat.
Freshwater ecosystems contributed several losses. This included the Chinese paddlefish (Psephurus gladius), a giant fish that could grow up to 23 feet long in the Yangtze River. Surveys confirmed its disappearance, with its population likely collapsing between 2005 and 2010 due to overfishing and habitat fragmentation from dam construction. Another significant freshwater loss was the Catarina pupfish (Megupsilon aporus) from Mexico, known only from a single spring that dried up due to groundwater extraction.
Amphibians, birds, and invertebrates also featured among the confirmed losses:
- The Cunning silverside (Atherinella callida), a small Mexican fish, was declared extinct after not being seen since 1957, with water pollution cited as a likely factor in its demise.
- The Poʻouli (Melamprosops phaeosoma), a rare bird endemic to the island of Maui in Hawaii, was officially declared extinct in 2019, having last been sighted in the wild in 2004.
- The Achatinella apexfulva tree snail, affectionately known as George, died in captivity in 2019, cementing the extinction of its species. This Hawaiian snail was one of hundreds of native snail species decimated by the introduction of the invasive rosy wolf snail.
- The Alagoas foliage-gleaner (Philydor novaesi), a bird from Brazil’s Atlantic Forest, was last seen in 2011.
- The Corky’s robber frog (Craugastor gollmeri) from Honduras, succumbed to a combination of habitat loss and fungal disease.
Primary Drivers of These Extinctions
The disappearances confirmed in 2019 were driven by recurrent human-related factors that often act in combination.
Land and Sea Use Change
The largest driver was land and sea use change, which includes the destruction and fragmentation of specific habitats. This was responsible for the loss of the Alagoas foliage-gleaner, whose forest home was cleared for agriculture and charcoal production.
Overexploitation and Resource Extraction
The overexploitation of organisms, primarily through unsustainable fishing and hunting, contributed directly to the loss of the Chinese paddlefish. For localized species like the Catarina pupfish, the extraction and diversion of water resources led to the complete destruction of their entire habitat.
Climate Change and Invasive Species
Climate change was a definitive driver in the extinction of the Bramble Cay melomys, which was wiped out by rising sea levels and storm surges. Invasive alien species were responsible for the demise of the Hawaiian tree snail. The Corky’s robber frog was likely lost due to habitat loss combined with the spread of infectious diseases, such as the chytrid fungus.