Nilgai antelope behavior and movement: Implications for cattle fever tick eradication

Authors: ZOROMSKI, LISA - TEXAS A&M UNIVERSITY; DEYOUNG, RANDY - TEXAS A&M UNIVERSITY; Goolsby, John; FOLEY, AARON - TEXAS A&M UNIVERSITY; ORTEGA-S, J - TEXAS A&M UNIVERSITY; HEWITT, DAVID - TEXAS A&M UNIVERSITY; CAMPBELL, TYLER - EAST FOUNDATION

Submitted to: The Wildlife Society
Publication Type: Proceedings
Publication Acceptance Date: 2/7/2019
Publication Date: 2/23/2019
Citation: Zoromski, L.D., Deyoung, R.W., Goolsby, J., Foley, A., Ortega-S, J.A., Hewitt, D.G., Campbell, T.A. 2019. Nilgai antelope behavior and movement: Implications for cattle fever tick eradication. The Wildlife Society. p. 123.

Interpretive Summary: Nilgai antelope (Boselaphus tragocamelus) were first introduced to Texas rangelands during the 1920’s – 1940’s. Native to India, Nepal, and Pakistan, nilgai have expanded into much of coastal South Texas and northern Mexico. Nilgai have the ability to spread cattle fever ticks (CFT; Rhipicephalus annulatus and R. microplus). Cattle fever ticks can transmit bovine babesiosis to cattle, a serious economic threat to the U.S. cattle industry.The USDA-ARS has developed remotely activated sprayers as a treatment measure for nilgai. However, the sprayers must be positioned in locations that nilgai use frequently. Research is lacking on nilgai behavior, but nilgai regularly re-visit fence crossings and latrines, where repeated defecations occur at a localized site. We are assessing frequency, time, sex, and age of nilgai that use latrines and fence crossings via camera traps on 3 South Texas ranches. With 6 months of preliminary data, we found fence crossings to be used at a 50:50 sex ratio, while latrines are visited mostly by adult males. Both crossings and latrines are visited every 2-3 days on average. Latrines are visited more often at night, while crossings are used throughout the day. Estimates show hundreds of latrines on the ranches studied, making placement of sprayers on every latrine impractical. Fence crossings are less abundant, and may be more promising areas to administer sprayers. Knowledge of nilgai movement and behavior will help identify areas to place sprayers to help with the eradication of CFT in the U.S.

Technical Abstract: Nilgai antelope (Boselaphus tragocamelus) were first introduced to Texas rangelands during the 1920’s – 1940’s. Native to India, Nepal, and Pakistan, nilgai have expanded into much of coastal South Texas and northern Mexico. Nilgai provide a significant economic benefit to ranching operations. However, nilgai have the ability to spread cattle fever ticks (CFT; Rhipicephalus annulatus and R. microplus). Cattle fever ticks can transmit bovine babesiosis to cattle, a serious economic threat to the U.S. cattle industry. Incursions of CFT into South Texas from Mexico required the establishment of quarantine zones. This burdens infested ranches with expensive and time-consuming eradication requirements. Wildlife can hinder eradication efforts on livestock because white-tailed deer (Odocoileus virginianus) and nilgai are alternative hosts for CFT. Control methods, such as treated baits, are available for deer. Nilgai do not respond to bait, which is a major challenge for controlling the spread of CFT. The USDA-ARS has developed remotely activated sprayers as a treatment measure for nilgai. However, the sprayers must be positioned in locations that nilgai use frequently. Research is lacking on nilgai behavior, but nilgai regularly re-visit fence crossings and latrines, where repeated defecations occur at a localized site. We are assessing frequency, time, sex, and age of nilgai that use latrines and fence crossings via camera traps on 3 South Texas ranches. We are also identifying the number and distribution of latrines. Knowledge of nilgai movement and behavior will help identify areas to place sprayers to help with the eradication of CFT in the U.S.