Scientists are underestimating many species’ risk of extinction

“We were extremely surprised by how much the IUCN ranges overestimated what we deem the true ranges to be,” said researcher Don Melnick.
By Brooks Hays   |   April 26, 2017
Researchers found the geographical range of the Nilgiri flycatcher, Eumyias albicaudatus, is 65 percent smaller than estimates used by IUCN scientists. Photo by Adesh Shivkar/Columbia University

April 26 (UPI) — The extinction risks of many species are greatly underestimated, according to new research by ecologists at Columbia University.

The underestimation can be explained by overestimation, the new study — published in the journal Biological Conservation — shows. Researchers have been systematically overestimating the geographical range in which vulnerable species can thrive, the new study argues, suggesting extinction risk for many species is far greater than thought.

Maps featuring overly generous geological ranges are used by conservation organizations like the International Union for Conservation of Nature to determine a species’ threat status.

“Concerned about this issue, we aimed to determine how far off those maps were,” Don Melnick, a professor of conservation biology at Columbia, said in a news release. “In doing so, we found there is an enormous amount of freely available data on many species around the world that can be employed to get a better picture of exactly how many species are truly under extreme threat.”

“This picture, grim as it may be, is necessary if we are going to accurately plan the steps needed to stem those threats, locally and globally,” Melnick added.

Confirmed expert sightings are used to draw boundary lines and map a species’ geographic range. Morgan and his colleagues argue the technique routinely incorporates unsuitable habitat into the mapped range, causing ecologists with IUCN to overestimate species population and underestimate a species vulnerability.

To measure the problem, the researchers at Columbia decided to draw their own maps. They plotted the ranges of 18 bird species endemic to the Western Ghats, mountain range of southwest India.

The scientists used data from eBird, the largest citizen science database, to get a rough estimate of the bird’s range. They coupled the observations of citizen scientists with ecological data, including details on temperature, elevation, climate, vegetation and more. The combination of data allowed researchers to build what they believe to be more accurate estimations of each species’ current range.

When they compared their maps to those used by IUCN, they found the ranges of 17 of 18 species had been overestimated and included large swaths of unsuitable habitat. The new maps suggest at least 10 of the 18 species are more vulnerable than previously estimate and that their statuses should be elevated by the IUCN.

“We were extremely surprised by how much the IUCN ranges overestimated what we deem the true ranges to be,” said researcher Don Melnick. “In a number of cases the ranges were overestimated by an order of magnitude. The drastic reduction in range size and the increased habitat fragmentation that our study indicates leads us to infer that there is a much greater threat to these endemic birds than was ever imagined.”


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