Conflicts between African lions and human communities threaten the lion's survival throughout its range. A new study by Earthwatch Institute-supported scientists working in the Tsavo region of Kenya investigates the annual toll on livestock and provides a hopeful model for coexistence through compensation and seasonal livestock management.

The study, published online in the journal Biological Conservation, concludes that $8,749 would be needed annually to offset the economic damage of a vigorous population of 26 adult lions inhabiting two ranches in Kenya totaling 160,000 acres.

"Ranches are in the front lines of conservation," said Dr. Bruce Patterson, MacArthur Curator of Mammals at Chicago's Field Museum and author of the study. "Lions based in Tsavo National Park exact a toll on neighboring properties in terms of livestock. But the cost to ranchers per lion, $290 per year, is so small in Western terms that there ought to be some way to provide compensation and permit coexistence."

The study analyzed 312 attacks, primarily by lions, which claimed the lives of 433 head of livestock on two ranches adjoining Tsavo East National Park over four years in the late 1990s. Predators killed 2.4 percent of the herd, representing 2.6 percent of the herd's estimated economic value.

Although lions may once have been the world's most widespread terrestrial mammal species, experts recently estimated that as few as 22,600 African lions remain, 10 percent of their population just 25 years ago. Most of this decline can be attributed to conflicts with an expanding human population, specifically to depredations on livestock.

"As the number of lions continues to dwindle and humans continue to encroach on lion habitat, conservationists must seek creative ways to mitigate conflict between lions and humans over increasingly scarce resources," said Patterson, principal investigator of the Earthwatch-supported Lions of Tsavo project. "In order to be effective, conservation solutions must involve politics and economics, as well as biology."

Surprisingly, the study concluded that lion attacks in this arid scrubland increase during periods of precipitation. This contrasts with the pattern of lion predation elsewhere in Africa, such as the Serengeti, where lion attacks increase during dry spells. In Tsavo, dry seasons concentrate prey near water reservoirs, making them easy targets. Wet seasons, on the other hand, allow prey to disperse, exploiting scattered temporary water sources.

"Scattered prey are harder to hunt, prompting Tsavo lions to attack livestock," said co-author Dr. Roland Kays (New York State Museum), also a principal investigator on Lions of Tsavo. "A hungry lion is a dangerous lion."

The authors conclude by suggesting a seasonal stocking plan to reduce lion predation on local livestock in Tsavo. By quartering livestock only during the dry season and taking them to market before the annual rains, herders could take advantage of the growth of annual vegetation but avoid the majority of recurrent losses to predators.

Earthwatch teams working with Patterson and Kays were instrumental in documenting lion densities on the ranches, used to calculate the percentage of livestock in the population's diet and the biomass they must consume. The continued participation of Earthwatch volunteers will help the scientists further understand the local ecology of lions and help mitigate their conflicts with human communities.

"Mediating animal-human conflict is a central responsibility of Kenya Wildlife Service, which has a big job and scant resources and personnel," said Patterson. "Teaming up with our Earthwatch-supported research teams is like winning the lottery for them."

For more information, see "Livestock predation by lions (Panthera leo) and other carnivores on ranches neighboring Tsavo National Park, Kenya." Bruce D. Patterson , Samuel M. Kasiki, Edwin Selempo, and Roland W. Kays. Biological Conservation, 119: 507-516, or find it online at http://fm1.fieldmuseum.org/aa/Files/patterso/Biol_Cons_2004.pdf.

For more information on Tsavo's lions, see Patterson's new book, The Lions of Tsavo: Exploring the Legacy of Africa's Notorious Man-eaters.

Earthwatch Institute is an international nonprofit organization which supports scientific field research worldwide by offering members of the public unique opportunities to work alongside leading field scientists and researchers. The Institute's mission is to engage people worldwide in scientific field research and education to promote the understanding and action necessary for a sustainable environment