Nilgai Movements on El Sauz

On one hand, nilgai antelope are a prized trophy for hunters, offering year-round recreational opportunities. On the other hand, nilgai compete for forage with cattle and white-tailed deer, and are a host of cattle fever ticks, thus complicating tick eradication strategies. As such, nilgai are loved by some landowners and loathed by other landowners. Either way, more information is needed to develop effective nilgai management strategies.

Very little is known about the biology of nilgai on rangelands of South Texas, particularly related to their movement rates, patterns, and habits. In a recent publication investigating nilgai movements in South Texas, animals displayed no differences between sexes in home range size and had maximum home range axes between 8 and 10 miles. However, nilgai behavior was highly variable. New GPS collars allow for more detailed characterizations of animal movements.

Together with our partners, we placed 30 state-of-the art GPS collars on 15 cow nilgai and 15 bull nilgai in early April 2015 on our El Sauz Ranch. GPS locations from only a few months of sampling on the El Sauz
Ranch suggest:

  • About half of nilgai remained on the Ranch
  • About a quarter of nilgai used the Ranch and adjacent properties
  • About a quarter of nilgai moved away from the Ranch
  • For animals that have moved away from the Ranch, distances were from 1 to 30 miles

Our ultimate goal is to gain understanding of nilgai behavior and determine effective management unit size. This will enable landowners to make informed management decisions related to this non-native
animal.

Partners: Texas Animal Health Commission, United States Department of Agriculture, and Caesar Kleberg Wildlife Research Institute.

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