Little-known species are at even more risk of extinction, scientists say

The species scientists know least about are at an even higher risk of extinction because researchers are unable to tailor conservation efforts to their needs, according to researchers.

More than 4,300 species whose extinction risk cannot be assessed due to a lack of ecological data are likely at risk of extinction, according to study published in Communications Biology on Thursday.

Among the more than 26,000 species that have been assessed by the International Union for Conservation of Nature (IUCN), nearly 7,700 have been declared data deficient, meaning there is not enough data to make any sort of declaration on their extinction risk, Jan Borgelt, an ecologist at the Norwegian University of Science and Technology and author of the study, told ABC News.

Calculations based on previously published data on the geographical areas the species live in, as well as factors known to affect biodiversity -- such as climate change, land use by humans and threats posed by invasive species -- were used to predict extinction risk for data deficient species, according to the study.

The researchers found that about 56% of data deficient species are likely threatened with extinction compared with 28% of species that have been assessed for the International Union for Conservation of Nature Red List of Threatened Species.

This becomes a problem for those making conservation plans, Borgelt said.

"So in most cases, actually, these data deficiencies are just ignored in a lot of analysis simply because we don't know how threatened they are, if they're threatened at all," he said.

Extinction risks for data deficient species varied between groups and geographic areas. About 85% of amphibians, 40% of ray-finned fish, 61% of mammals, 59% of reptiles and 62% of insects are likely at risk of extinction, the study said.

For land-dwelling species that are data deficient, risk of extinction is prevalent among those that occupy smaller geographical areas within regions such as central Africa, southern Asia and Madagascar, the researchers found.

Maintaining the earth's biodiversity is critical because all life depends on the proper functioning of ecosystems -- such as clean water and carbon sequestration to help mitigate climate change, Borgelt said.

"Ultimately, functioning ecosystems depend on the species that live in those ecosystems," he said. "And once we lose species, we sort of distract these ecological networks."

The findings highlight potential biases in current conservation priorities as well as the importance of conservation for many data deficient species that are likely threatened by extinction, the paper concluded.

These assessments are "the very foundation of all conservation-related actions," Borgelt said.