e360 digest

02 Oct 2009: Loss of World’s Large Predators
Causing Alarming Rise in ‘Mesopredators’

The decline of the world’s large, or “apex,” predators is leading to an increase in smaller, so-called “mesopredators,” causing significant ecological and economic damage, according to a new study.

The populations of primary predators such as wolves, lions, and sharks have sharply declined because of hunting, fishing, and habitat disruption, researchers from Oregon State University say in a report published in the journal Bioscience. And in numerous cases worldwide, the next species in line including birds, sea turtles, lizards, rodents, and insects — have flourished, often with unintended consequences.

In Sub-Saharan Africa, for instance, the decimation of lion and leopard populations has caused a surge in populations of baboons, which increasingly destroy crops and menace villagers. Steep declines in sharks have led to increases in ray populations, which have decimated some bay scallop fisheries. In North America, the largest terrestrial species have declined for two centuries, enabling 60 percent of smaller predators to expand their ranges.

Among other findings, researchers say the surge in smaller predators has triggered collapses of entire ecosystems and led to significant plant and crop damage. The researchers said it may be more cost-effective to reintroduce apex predators into ecosystems than spending large sums controlling mesopredators. Yale Environment 360: Loss of World’s Large Predators Causing Alarming Rise in ‘Mesopredators’