The study done by a team of scientists from the World Wildlife Fund (WWF) and Princeton University pointed out how large mammals were vulnerable to extinction because of the increasing loss of their habitats to human settlements. If their numbers countinue to drop, it's going to have long-term effects on the health of an ecosystem.

They were able to find out that the tiger, elk, American bison, leopard, lion, horse, and wolf were being driven out of their habitats.

These mammals serve as landscape engineers as they are the top predators. Their numbers affect the health of an ecosystem.

The scientists were able to create a study that is the first of its kind to measure ecological impacts of humans on biodiversity based on the absence of native, large mammals - animals with a body mass over 44 lbs. Their study used AD 1500 as their baseline date reference since this was the time when there was a significant increase in colonization activity. Furthermore, this was also the time of the Industrial Revolution, where human activities had a big influence on nature.

On this, Eric Dinerstein, WWF's Chief Scientist and Vice-President of Conservation Science, commented that,

...we can now pinpoint places where large mammal assemblages still play important roles in terrestrial ecosystems. Second, we now have targets where through strategic reintroductions - such as returning wolves to Yellowstone - we can restore intactness in places missing one or two species and recover the ecological fabric of these important conservation landscapes.

With this new found knowledge, perhaps further extinction of animals could be avoided and eventually efforts could be made to restore nature back to its health.