Toronto Star : Humans deadly to other species

Humans deadly to other species

New study of mammals shows large animals have been pushed to globe's farthest reaches

Peter Calamai | Science Reporter | January 1, 2008

The expansion of humanity that began with European colonization has exacted a far deadlier toll than previously realized on the world's other large land mammals, a new study has found.

Only one-fifth of the Earth's surface is today home to the same diversity of large mammals as five centuries ago and most of that lies in six remote wilderness areas, such as the Canadian Arctic and the Amazon basin.

Wildlife researchers say this large-scale vanishing act is bad news for the continued health of ecological systems.

"Areas retaining a full complement of large mammals are more likely to be ecologically functional than those missing one or more large mammal species," warns John Morrison of the World Wildlife Fund.

Morrison and colleagues produced this sombre picture of humanity's impact by assembling the first-ever picture of global mammal populations then and now, published in the current issue of the Journal of Mammalogy.

The big losers include iconic wild animals such as the lion, tiger and rhinoceros, but also the brown bear, elk and wild horse. They have all been pushed out by exploding human settlement and hunting, often losing habitat ranges larger than Canada.

The researchers define large mammals as those weighing more than 20 kilograms. At least a third of the 263 species studied have lost more than half their former habitat range since 1500, the date when extensive European colonization began.

Only seven large mammals have actually become extinct in that period but many others survive largely in remote wildernesses or protected areas. Ten parks and reserves in sub-Saharan Africa each conserve more than 25 species, the greatest number in the world.

By contrast, the Arctic Archipelago is a refuge for only three species – caribou, musk ox and grey wolf.

Yet the grey wolf has been successfully reintroduced in parts of North America, a success wildlife researchers say should be repeated with other threatened large mammals, along with other conservation measures.

"There is a strong need for creation of new reserves in unprotected areas and enhanced efforts to prevent poaching and habitat degradation within current reserves," they write.

The research identified 108 areas that still retained the same mix of large mammals present there in 1500, ranging from tiny Bawean Island in Indonesia to all of Siberia.

But only a quarter of these areas have the bulk of their land under some sort of conservation protection. The Arctic Archipelago is listed as "poorly" protected and north-central and Eastern Canada as "partially."

The researchers drew upon 500 written sources plus interviews with experts to create the range maps for individual mammal species in 1500. Current distribution information came from an international study now underway called the Global Mammal Assessment.