Habitat Connectivity

The catastrophic decline around the world of “apex” predators such as wolves, cougars, lions or sharks has led to a huge increase in smaller “mesopredators” that are causing major economic and ecological disruptions, a new study concludes.

The findings, published October 1 in the journal Bioscience, found that in North America all of the largest terrestrial predators have been in decline during the past 200 years while the ranges of 60 percent of mesopredators have expanded. The problem is global, growing and severe, scientists say, with few solutions in sight.

An example: in parts of Sub-Saharan Africa, lion and leopard populations have been decimated, allowing a surge in the “mesopredator” population next down the line, baboons. In some cases children are now being kept home from school to guard family gardens from brazen packs of crop-raiding baboons.

In case after case around the world, the researchers said, primary predators such as wolves, lions or sharks have been dramatically reduced if not eliminated, usually on purpose and sometimes by forces such as habitat disruption, hunting or fishing. Many times this has been viewed positively by humans, fearful of personal attack, loss of livestock or other concerns. But the new picture that’s emerging is a range of problems, including ecosystem and economic disruption that may dwarf any problems presented by the original primary predators.

The elimination of wolves is often favored by ranchers, for instance, who fear attacks on their livestock. However, that has led to a huge surge in the number of coyotes, a “mesopredator” once kept in check by the wolves. The coyotes attack pronghorn antelope and domestic sheep, and attempts to control them have been hugely expensive, costing hundreds of millions of dollars.

The problems are not confined to terrestrial ecosystems. Sharks, for instance, are in serious decline due to overfishing. In some places that has led to an explosion in the populations of rays, which in turn caused the collapse of a bay scallop fishery and both ecological an economic losses.

Source and complete article: ScienceDaily (Oct. 4, 2009)

The Asiatic black bear is now listed as vulnerable, therefore six of the eight species of bear in the world are now officially facing extinction.

The smallest, the sun bear, is the latest to be classified as vulnerable on the Red List of Threatened Species. Four other species – Asiatic black bear, Sloth bear, Andean bear and Polar bear – are also listed as vulnerable.

The giant panda is facing the greatest threat and remains in the endangered category. There is least concern over the European brown bear and the American black bear.

The sun bear found in Souteast Asia, Sumatra and Borneo, will be included in the 2007 Red List drawn up by the World Conservation Union (IUCN). Previously it was known as ‘Data Defficient’ meaning not enough was known about it to give it a classification. Rob Steinmetz, co-chair of the IUCN Bear Specialist Group’s sun bear expert team, said: “Although we still have lot to learn about the biology and ecology of this species, we are quite certain that it is in trouble.

“We estimate that sun bears have declined by at least 30 per cent over the past 30 years (three bear generations), and continue to decline at this rate. Deforestation has reduced both the area and quality of their habitat. Where habitat is now protected, commercial poaching remains a significant threat.

“We are working with governments, protected area managers, conservation groups and local people to prevent extinction of the many small, isolated sun bear populations that remain in many parts of Southeast Asia.”

Bear hunting is illegal throughout Southern Asia, but they suffer heavy losses from poachers, who risk the small chance of being caught against lucrative gains from selling parts. Bile from the bear’s gall bladder is used in traditional Chinese medicine and their paws are consumed as a delicacy. Additionally, bears are often killed when they prey on livestock or raid agricultural crops. Bears simply roaming near a village may be killed because they are perceived as a threat to human life.

Dave Garshelis, co-chair of the Bear Specialist Group, which met earlier this month in Mexico, to update the status of the eight species, said: “Although the bear population estimates for Asia are not as reliable as we would like, we estimate that bears in Southeast Asia are declining at a particularly rapid rate due to extensive loss of forest habitat combined with rampant poaching.”

Bruce McLellan, also a co-chair, said: “An enormous amount of effort and funding for conservation and management continue to be directed at bears in North America where their status is relatively favourable. It is unfortunate that so little is directed at bears in Asia and South America where the need is extreme. We are trying to change this situation but success is slow.”

By Paul Eccleston, Telegraph.co.uk