According to a recent study published in the Proceedings of the National Academy of Sciences, roughly 23,000 African elephants were killed for their tusks in 2006. As a consequence of illegal ivory poaching, elephant numbers are dwindling in many west, central and east African countries. However, in southern Africa, where 58 percent of the elephant population resides, numbers are rising to problematic levels. Scientists are now beginning to explore alternatives to culling in order to sustainably manage expanding elephant populations.
The Problem of Overpopulation
South Africa's Kruger National Park is famous for providing international tourists with the ability to view Africa's "Big Five": the elephant, rhino, lion, leopard, and buffalo. Currently, the Park is home to roughly 14,000 elephants, a 75 percent increase since culling was stopping in 1994. With a growth rate of six to seven percent a year, the population is expected to double by 2020.
Elephants inflict a heavy toll on surrounding vegetation, consuming up to 660 pounds of grass, leaves and twigs each day. As populations increase beyond the capacity of the land, both elephants and other important species are at risk of hunger and conflict over resources.
Options for Population Management
Between 1967 and 1994, South Africa culled 14,562 elephants. Without this effort, it is estimated that the population would now total 80,000 (as opposed to the current total of 20,000). However, culling has not provided a feasible long-term solution since it requires continuous effort and is internationally controversial. Researchers are now exploring more sustainable solutions, including reducing the number of watering holes, removing fences to create transborder "megaparks," and relocation. Deciding which method, or combination of methods, is optimal will require improved understanding of elephant numbers and movements. According to a recent article in Science, a new research group will be outfitting 91 elephants in seven southern African countries with GPS tracking collars in an effort to monitor the ecological impacts of various approaches.
RELATED LINKS:
World Conservation Union (IUCN) African Elephant Database
African Elephant Status Report 2007
World Wildlife Fund African Elephant Factsheet
EarthTrends
Biodiversity and Protected Areas Searchable Database
（引自earthtrends.wri.org    2007年3月9日）