The terms foreign, introduced, and exotic have different connotations but are often used interchangeably to refer to foreign species introduced into new environments. Since colonization began, thousands of species of plants and animals have been brought to North America; many are now in Texas. The term exotic is commonly applied in Texas to foreign big game acquired by private landowners and released within fenced enclosures or allowed to range free.
Although exotics are not distributed statewide, several species have become prominent in certain regions. The most popular and numerous are species of deer, antelope, and sheep. Though less popular as a game animal, the European wild swine is among the most numerous introduced species.
Most of the more successful free-ranging exotic species in Texas come from the Asian continent. Axis deer, nilgai antelope, and blackbuck antelope were originally from India; the sika deer was imported from Southeast Asia. The mouflon sheep was from Sardinia and Corsica, the fallow deer from Asia Minor and southern Europe, and the European wild swine from Europe. The aoudad sheep was brought to Texas from North Africa.
Texans have acquired exotics to observe for pleasure, to substitute for extirpated native big game, to increase the variety of game for hunting, to increase production and income from rangelands by using combinations of animals that have varied food habits, and to sustain populations of species that are endangered on their native ranges. Most of the original exotic brood stock in Texas came from zoos. Subsequent stocking has been with animals mainly purchased from private landowners, zoos, and animal dealers. Exotics are not protected by the regulations that cover native game animals, and they are hunted at the prerogative of the landowner. Exceptions are the axis deer in Bexar and Kendall counties and aoudad sheep in counties contiguous to Palo Duro Canyon, where they are under state game regulations.
Perhaps the earliest releases of exotics were of nilgai antelope acquired by the King Ranch between 1930 and 1941 from the San Diego Zoo and stocked on the ranch's South Texas rangelands. During the same decade blackbuck antelope and axis (also called chital and spotted) deer, sika deer, and sambar deer were released. From the late 1930s through the 1950s mouflon sheep, eland antelope, red deer, swamp deer (barasingha), and other species were released.
Today, more species and greater numbers of exotic big game are in Texas than anywhere else in North America. The first statewide census of exotics by the Texas Parks and Wildlife Department in 1963 found thirteen species and 13,000 animals. The 1984 survey revealed about seventy-five species and 120,000 animals. Some species, such as the nilgai, are probably more numerous in Texas than they now are in their native habitats.
Exotics are found in about half of the 254 Texas counties; 55 percent are concentrated in the Edwards Plateau. South Texas has 18 percent, and most of the remaining number are in localized areas of North, central East, and far West Texas. About 70 percent are confined on pastures by game-proof fences. The remaining 30 percent range free. The most numerous species have developed substantial free-ranging populations.
Hybridization or intergradation has occurred between some species and subspecies through planned breeding and by chance; consequently, there are free-ranging individuals that are atypical of the species. Examples are mouflon that have crossed with Barbados and other breeds of domestic sheep, and crosses between swine and domestic feral swine.
Because exotic populations are localized and are found on private lands where their availability is limited, the general public is not aware of their numbers. Most exotics have been released without regard for their chances for survival, their compatibility with native biota, and their roles in the introduction and spread of diseases. Major studies on exotics in Texas have been done by the Texas Parks and Wildlife Department, Texas A&M University, Texas Tech University, and Texas A&I University (now Texas A&M University–Kingsville). The Caesar Kleberg Foundation, under the direction of Richard B. Davis, funded much of the early research. The most studied species have been the axis, nilgai, blackbuck, sika, fallow, and aoudad; little is known about the ecology of other species.
Generally, though Texas exotics have fared well and ecological complications have been few, even successful free-ranging populations have occasionally had difficulty with their Texas habitat. Nilgai, blackbuck, and axis evolved in warm climates and are not physiologically adapted to withstand severe cold. Some have died during unusually cold winters. Aoudad have died from infestations of liver flukes, endoparasites for which the sheep are new hosts. Studies indicate that axis, sika, fallow, and nilgai are dominant competitors with native deer for food, and on some heavily populated ranges, native deer are declining as the exotics increase. A major need is proper control of their numbers where prolific free-ranging populations exist. Favorable economic methods of control are to harvest them by sport hunting and for meat. New management changes have begun to emphasize the husbandry of exotics, not just stocking and hunting. The new commercial enterprise involves the production of brood stock, meat, and body parts such as antlers (which are sold as aphrodisiacs in Asia). Exotic meat for human food is gaining attention in the United States, and exotic game dishes are becoming popular in restaurants. Because of the large number of foreign animals and the ecological backlashes they have often caused, many people are opposed to having exotics free-ranging in this country. In Texas, however, where large numbers of exotics are firmly established, the concern now is understanding their ecological roles and practicing sound management.