I've been blessed to be able to hunt 3 family owned cattle ranches with a great game management program including all the native species plus a wide assortment of exotics for the past 20 years. While this is a high fence operation, combined acreage is over 21,000 acres and all exotics are brought in, allowed to become acclimated within a large (posted) pasture, then released to roam free within the high outer perimeter fence.
One of the most popular and plentiful of the many exotics is the Nilgai, an antelope from India. These were first released by a circus which went bankrupt onto the King Ranch during the depression and have multiplied across south Texas.
Nilgai are excellent table fare, very lean meat. Mature Bull can reach a weight of 650# w/a charcoal grey coloration
Cows are reddish brown, weigh up to 450#. Young bulls are also this color but have buttons which develop into horns as they mature.
Most of the year the bulls run in bachelor groups, cows with calves in separate groups. During the rut, it is every bull for himself.
Two bulls square off by circling one-another in an ever tightening arc until contact is made.
When both bulls seemed to be exhausted, the circle slowly expanded and one, apparently conceding defeat slowly walked off into the brush, leaving the victor to claim the prize.
More details here.