Movement patterns of nilgai antelope in South Texas: Implications for cattle fever tick management.

Wildlife, both native and introduced, can harbor and spread diseases of importance to the livestock industry. Describing movement patterns of such wildlife is essential to formulate effective disease management strategies. Nilgai antelope (Boselaphus tragocamelus) are a free-ranging, introduced ungulate in southern Texas known to carry cattle fever ticks (CFT, Rhipicephalus (Boophilus) microplus, R. (B.) annulatus). CFT are the vector for the etiological agent of bovine babesiosis, a lethal disease causing high mortality in susceptible Bos taurus populations and severely affecting the beef cattle industry. Efforts to eradicate CFT from the United States have been successful. However, a permanent quarantine area is maintained between Texas and Mexico to check its entry from infested areas of neighboring Mexico states on wildlife and stray cattle. In recent years, there has been an increase in CFT infestations outside of the permanent quarantine area in Texas. Nilgai are of interest in understanding how CFT may be spread through the landscape. Thirty nilgai of both sexes were captured and fitted with satellite radio collars in South Texas to gain information about movement patterns, response to disturbances, and movement barriers. Median annual home range sizes were highly variable in males (4665ha, range=571-20,809) and females (1606ha, range=848-29,909). Female movement patterns appeared to be seasonal with peaks during June-August; these peaks appeared to be a function of break-ups in female social groups rather than environmental conditions. Nilgai, which reportedly are sensitive to disturbance, were more likely to relocate into new areas immediately after being captured versus four other types of helicopter activities. Nilgai did not cross 1.25m high cattle fences parallel to paved highways but did cross other fence types. Results indicate that females have a higher chance of spreading CFT through the landscape than males, but spread of CFT may be mitigated via maintenance of cattle fences running parallel with paved highways. Our results highlight the importance of documenting species-specific behavior in wildlife-livestock interfaces that can be used to develop effective disease management strategies in the United States and worldwide.

Comparison of natural and artificial odor lures for nilgai (Boselaphus tragocamelus) and white-tailed deer (Odocoileus virginianus) in South Texas: Developing treatment for cattle fever tick eradication.

Cattle fever ticks (CFT), vectors of bovine babesiosis and anaplasmosis, were eradicated from the United States by 1943, but are frequently reintroduced from neighboring border states of Mexico via stray cattle and wildlife hosts including white-tailed deer (Odocoileus virginianus) (WTD) and nilgai antelope (Boselaphus tragocamelus). Nilgai antelope are exotic bovids from India that are hosts of CFT, have large home ranges as compared to WTD, thus have the potential to spread CFT through the landscape. Currently, there are no methods to control CFT on nilgai. Odor lures were evaluated to determine if nilgai could be attracted to a central point for development of control methods. Four treatments, nilgai offal a natural odor lure was used as the positive control; and compared to three artificial odors; screw worm lure, volatile fatty acids, citronella oil. Studies were conducted on a free-ranging population of nilgai at the East Foundation's Santa Rosa Ranch (Kenedy Co., near Riviera, Texas, USA). Game cameras were used to document visitation to the lures. In the ten randomly placed transects, 110 nilgai and 104 WTD were photographed. Offal had significantly more visits by nilgai (71% of total visits) than screwworm (15%), VFA (11%), and citronella (4%). For WTD, there was no significant difference in visitation at the lure treatments.

Use of Remote Cameras to Monitor the Potential Prevalence of Sarcoptic Mange in Southern Texas, USA.

Sarcoptic mange, caused by the mite Sarcoptes scabiei , is a common, highly contagious skin disease that has been reported from more than 100 species of mammals, including humans. Our objectives were to 1) determine the prevalence of sarcoptic mange within mammals from southern Texas, and 2) determine the efficacy of using remote cameras to estimate mange prevalence. We collected remote camera photographs from a 64-km2 area and blood and skin scrapings from 166 mammals representing 12 species in southern Texas, US during 2012-13. Only 16% of the 344,395 photograph series were of animals with an appearance consistent with sarcoptic mange and only individuals of four species: 16/25 feral hogs ( Sus scrofa ), 13/28 white-tailed deer ( Odocoileus virginianus ), 18/25 coyotes ( Canis latrans ), and 1/5 nilgai ( Boselaphus tragocamelus ) displayed alopecia, seborrhea, and crusted lesions that were consistent with mange. However, only feral hogs, coyotes, and white-tailed deer had mites present within skin scrapings. Two photographs of each collected mammal that displayed characteristics consistent with mange (n=83 animals; 166 photographs) were reviewed in a blind trial by a veterinarian experienced with cases of mange. The veterinarian correctly identified 18 and 97 animals from photographs as positive and negative for mange, respectively, with 19, 9, and 23 animals from photographs being false positive, false negative, and inconclusive, respectively. Moderate to severe cases of mange were readily identifiable via photographs; however, mild cases and summer coats often were misdiagnosed, making the technique of debatable use.