Many animal species facing extinction: Study
Thanks to the excessive exploitation of natural resources by man, many animal species are either dead or are on way to their eminent death.
The threat of mass extinction that the world is facing is much more severe than its perception, says a new study done by researchers from Stanford University and the National Autonomous University of Mexico. The study has been published in journal Proceedings of the National Academy of Sciences (PNAS).
The demise of billions of animals from thousands of species both rare and common means the sixth mass extinction event is already underway, says the study.
So far, during the 500 million years of earth’s history there have been five mass extinctions, each of which resulted in disappearance of nearly 75 per cent of existing species.
The most recent mass extinction occurred some 66 million years ago, when 76 per cent of all species were lost due to volcanic activity, climate change and asteroid impact. Dinosaurs too disappeared at this time.
The study attributes the declining number of both common and rare species to a number of factors including, habitat loss, over-exploitation, invasive organisms, pollution, toxification and climate disruption.
Several species of mammals e.g. cheetahs, orangutans, lions, pangolin and giraffes, that were relatively safe one or two decades ago are now endangered. Though the earth’s habitat is not immediately threatened, it is nevertheless, facing a major loss in its biodiversity.
The study used a sample of 27,600 terrestrial vertebrate species and 177 mammal species that faced population extinction between 1900 and 2015 which showed extremely high degree of population decay in vertebrates, even in species of low concern.
Of the 27,600 species that comprises nearly half of known vertebrate species, a third or 8,851 have decreased in population size and geographic range, even though they are not currently considered endangered, the study found.
In the 177 mammals, all have lost 30 per cent or more of their geographic ranges, while more than 40 per cent have experienced severe population decline with more than 80 per cent range shrinkage.