Big animals like elephants, rhinoceros and hippopotamus could vanish within the next hundred years as smaller creatures, which can adapt to more confined habitats will flourish, new research shows.
Researchers at the University of Southampton found that the body mass of mammals will collectively reduce by 25 per cent over the next century as humans encroach onto their land.
Although most of the reduction will be caused by the extinction of large animals, some bigger creatures may actually shrink in size as they are forced to deal with smaller living environments.
Experts studied nearly 15,500 mammals and birds across the globe and used computer modelling to predict how expected habitat loss would impact populations.
While creatures like the Asian elephant, Javan rhinoceros and giraffe will struggle with habitat loss, animals expected to flourish include brown rat, bush rat, and blackbird which are more adaptable.
Rob Cooke, lead author of the study published in the journal Nature Communications, said: “By far the biggest threat to birds and mammals is humankind - with habitats being destroyed due to our impact on the planet, such as deforestation, hunting, intensive farming, urbanisation and the effects of global warming.
“The substantial 'downsizing' of species which we forecast could incur further negative impacts for the long-term sustainability of ecology and evolution.
“In the future, small, fast-lived, highly-fertile, insect-eating animals, which can thrive in a wide-variety of habitats, will predominate.”
Many scientists now believe that Earth has already entered a sixth mass extinction event with animals now dying out at 100 times the normal rate, scientists have warned.
Humans have created a toxic mix of habitat loss, pollution and climate change, which has already led to the loss of at least 77 species of mammals, 140 types of bird since and 34 amphibians since 1500.
They include creatures like the dodo, Steller’s Sea Cow, the Falkland Islands wolf, the quagga, the Formosan clouded leopard, the Atlas bear, the Caspian tiger and the Cape lion.
Natural population changes in the wild usually lead to two species of mammals dying out every 10,000 years. But the current rate is 114 times that level.
Felix Eigenbrod, Professor of Applied Spatial Ecology, at the University of Southampton, added: "We have demonstrated that the projected loss of mammals and birds will not be ecologically random - rather a selective process where certain creatures will be filtered out, depending on their traits and vulnerability to ecological change."