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Loss of African Wildlife Spurs Cascade of Consequences in Savannas, Says New Study Led by Bard Biology Professor

Mark Primoff
Bard College Biology Professor Felicia Keesing
ANNANDALE-ON-HUDSON, N.Y.— The loss of large mammals from African savannas can have unexpected and often undesirable consequences for the people and livestock that depend on them, according to a new study published today in the journal BioScience.

Scientists from Bard College and the University of California, Davis, experimentally removed large grazing mammals from plots of savanna land in Kenya where both livestock and wildlife are abundant. That removal, the researchers found, set in motion a cascade of consequences. Most significantly, populations of a small grazing mammal, the pouched mouse, doubled. The mice attracted venomous snakes like the olive hissing snake, devastated tree seedlings, and doubled flea populations, which potentially increased the risk of transmission of flea-borne pathogens.

“The results of this long-term study show that preserving large mammals in African savannas can be a win-win for conservation and for human welfare,” says lead author Felicia Keesing, a biology professor at Bard. “Large mammals like giraffes, zebras, and elephants keep rodents in check, which in turn reduces the number of venomous snakes and the number of fleas that can transmit diseases. Through their effects on rodents, large mammals also increase the survival of tree seedlings.”

The study was undertaken at the Kenya Long-term Exclusion Experiment (KLEE) in the Laikipia plateau, a project led by Truman Young, a UC Davis professor and restoration ecologist. For the past 19 years, Young and scientists at KLEE have been experimentally excluding wildlife and livestock from 18 different 10-acre savanna study plots and monitoring the effects, gaining important insights into the effects of livestock and wild animals on each other and on rangeland ecology. African savannas are among the most productive grasslands on Earth and host an abundance of wildlife, including zebras, lions, and leopards. This productivity also makes the savannas attractive to people who want to live there and raise their cattle, sheep, and goats. As human populations increase, wildlife needs come into conflict with the needs of people and the livestock they tend. However, the study shows that careful coordination between them could benefit both humans and wildlife, at least in some cases.

“The relationship between wildlife and livestock is complicated,” says Young. “But the negative impact of wildlife on livestock is often less severe than we’d have guessed, mitigated by the kinds of responses we have seen in the rodents.”

The study received primary funding from the National Science Foundation.

Felicia Keesing is David and Rosalie Rose Distinguished Professor of Science, Mathematics, and Computing and director of the Biology Program at Bard College. She is a community ecologist who studies the consequences of interactions among species and is particularly interested in how species diversity affects disease transmission. Her primary research is based at the Cary Institute of Ecosystem Studies in Millbrook, New York, where, together with colleague Rick Ostfeld, she investigates how the risk for humans of contracting Lyme disease is influenced by interactions among forest vertebrates, the causative agent of Lyme disease, and its vector, the blacklegged tick (Ixodes scapularis). Since 1995, she has studied how African savannas function when the large, charismatic animals, like elephants, buffaloes, zebras, and giraffes, disappear. She also studies how interactions among species influence the probability that humans will be exposed to infectious diseases. Keesing and fellow Bard Biology Professor Michael Tibbetts currently have two grants from the National Science Foundation to study anaplasmosis and babesiosis, two emerging tick-borne diseases in humans. Keesing has received grants from the National Geographic Society, National Science Foundation, National Institutes of Health, and Environmental Protection Agency, among others, and her awards include the United States Presidential Early Career Award for Scientists and Engineers (2000). She has contributed to articles in Nature, Proceedings of the National Academy of Sciences, Ecology Letters, Emerging Infectious Diseases, Proceedings of the Royal Society, Ecology, BioScience, Conservation Biology, Trends in Ecology & Evolution, Vector-Borne and Zoonotic Diseases, and Canadian Journal of Zoology, among other leading publications. Keesing has a Ph.D. from the University of California, Berkeley and a B.S. from Stanford University.

Media contacts:

Mark Primoff, Bard College Director of Communications, 845-758-7412,

Felicia Keesing, Bard College, 845-752-2331,

Kat Kerlin, UC Davis News and Media Relations, 530-752-7704,

Truman Young, UC Davis Plant Sciences, 530-754-9925,

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This event was last updated on 05-07-2014