Tigers and polar bears’ huge appetites make them much more vulnerable to environmental change, scientists said today.
Large predators suffer more than smaller species from overhunting and habitat change because they have to work so hard to find their next meal.
Experts matched studies of predator populations to the abundance of their prey and found populations of the largest species, such as lions, tigers or polar bears, dropped more when food was scarce than smaller species, such as weasels or badgers.
It suggests that the vulnerability of larger species may be linked with the high energetic costs of being “big”.
The robustness and large size of these species, which are well suited for hunting large prey, might become a hindrance when times are tough, prey are rare, and individuals have to work harder to find their next meal.
Dr Phillip Stephens, from Durham University’s School of Biological and Biomedical Sciences, said when prey was scarce, large predator populations dropped five to six times more than those of their smaller rivals.
He said: “It’s hard work being a large predator roaming and hunting across extensive areas to find food.
“The apparent vulnerability of tigers and polar bears to reductions in the availability of prey may be linked to the energetic costs of being a large carnivore.
“We found that the largest species exhibited a five to six-fold greater decrease in relative abundance in response to a decrease in their prey.”
He said the study showed the need for more detailed research to aid carnivore conservation.
“It shows how much more remains to be understood about the relationship between predators and their prey.”
Dr Chris Carbone, senior research fellow at the Institute of Zoology, the Zoological Society of London, said: “This study helps us to understand why large carnivores are particularly sensitive to environmental disturbance and why the protection and conservation of their habitat and, in particular, of their prey, are so important to global initiatives to save large carnivores in the wild.”
The review of studies of 11 species of carnivores by researchers from Durham University and the Zoological Society of London is published in the Royal Society journal Biology Letters today.