The global population of tigers has experienced an increase this year after a century due to extreme conservational efforts. However, another big cat, the leopard, is not doing as well as its striped cousin.

"Leopards' secretive nature, coupled with the occasional, brazen appearance of individual animals within megacities like Mumbai and Johannesburg, perpetuates the misconception that these big cats continue to thrive in the wild-when actually our study underlies the fact that they are increasingly threatened," said Luke Dollar, a co-author and the program director of the National Geographic Society's Big Cats Initiative, said in a statement.

According to the study published in the journal PeerJ, a new comprehensive study of leopards revealed that the iconic big cats have lost 75 percent of their historic range, from 35 million square kilometers (13.5 million square miles) to approximately 8.5 million square kilometers (3.3 million square miles) throughout Africa, the Middle East and Asia. To make matters worse, only about 17 percent of the existing range of leopard is legally protected.

For the study, researchers analyzed more than 1,300 sources on the leopard's historic and current range. Upon reviewing all the available data, the researchers discovered that four leopard subspecies, which include the Javan (P. p. melas), Persian (P. p. saxicolor), Indochinese (P. p. delacouri), and Sri Lankan (P. p. kotiya), are at the verge of extinction.

Meanwhile, the three subspecies that experienced the most decline in their numbers are Amur (P. p. orientalis), Arabian (nimr), and north Chinese (japonensis).

Despite being powerful and adaptive, human activities such as poaching and deforestation continue to decrease the global population of leopards. Leopard's skin is still prized in some parts of Africa. Uncontrollable trophy hunting also plays a crucial role in the recent decline of leopards.

With their findings, researchers hope that global conservation groups will strengthen their efforts in protecting the remaining ranges of leopards.

Their study is in-line with the change of Leopard's Red List Status, from "near threatened" to "vulnerable".