White-tailed Deer, Nilgai, and Cattle Grazing Interactions

Non-native animals often threaten the productivity of native rangelands. Nilgai, native to India, are one such large herbivore. First, nilgai compete for food with white-tailed deer and cattle. This becomes a major problem during periods of drought when food is scarce. Second, nilgai are alternative hosts of cattle fever ticks, which carry the deadly cattle disease – Texas Cattle Fever (A.K.A. bovine babesiosis), which is a significant threat to the U.S. cattle industry.

On the forage competition front, East Foundation and its research partners conduct extensive vegetation sampling across its four largest properties – the San Antonio Viejo, El Sauz, Santa Rosa, and Buena Vista ranches. Plant (both grass and forb) biomass and diversity are determined, from which annual estimates of grazing intensity and forage standing crop (available pant material) are known. Concurrent analysis of animal tissues (blood, hair, and dung) allow for the reconstruction of animal diets to determine diet overlap and assess competition. An unexpected outcome was the finding that during periods of drought nilgai diets are more like white-tailed deer than cattle.

Thus, nilgai are more likely to compete with deer for woody plants than with cattle for grass during dry times. Efforts to better understand these and other foraging interactions continue.

With regards to cattle fever ticks and nilgai, East Foundation has partnered with other organizations and government agencies to answer critical questions, mainly aimed at developing methods to treat ticks on nilgai. Some of these include:

• How far do nilgai move? How large of an area do nilgai use?
• What time of day are nilgai most active?
• Do nilgai attractants exist?
• How often do nilgai cross through holes in fences?
• Why do nilgai use latrines (large dung piles)?
• Can you determine the age of a nilgai from its teeth?

East Foundation is committed to using science and state-of-the art tools to provide solutions to problems threatening native rangelands.

For more information or questions about this project contact Andrea Montalvo at amontalvo@eastfoundation.net.