The South African oryx, or gemsbok (Oryx gazella), is an antelope native to the arid Kalahari Desert. This large ungulate, which can weigh up to 450 pounds and is recognizable by its long, straight horns, was intentionally introduced into New Mexico decades ago. It is considered a non-native, or exotic, species within the Chihuahuan Desert ecosystem, where it now thrives. Its presence in the American Southwest represents a successful exotic introduction that requires ongoing population management.
The History of Oryx Introduction in New Mexico
The establishment of oryx in New Mexico was part of a program initiated by the New Mexico Department of Game and Fish (NMDGF) in the 1960s. The goal was to diversify big-game hunting opportunities. Officials noted the ecological similarity between the Kalahari Desert and the Tularosa Basin, believing the species would be well-suited to the area’s arid conditions. The rationale was to create a new resource for hunters where native big-game species were less abundant.
The introduction program began with the release of captive-bred oryx offspring onto the White Sands Missile Range (WSMR) between 1969 and 1977. A total of 95 animals were released onto the Tularosa Range, a vast, restricted area that provided an initial sanctuary. The first regulated public hunt took place in 1974, marking the start of a popular hunting tradition. The oryx quickly expanded its range and population far beyond the initial expectations of state game managers.
Current Population Estimates and Geographic Distribution
The number of oryx in New Mexico has grown substantially since their introduction, far exceeding initial management goals. While exact figures are difficult to obtain for a free-ranging species, the population is estimated to be between 3,000 and 5,000 animals. This rapid growth is attributed to the species’ physiological adaptations to aridity, continuous reproduction, and the lack of natural predators in the Chihuahuan Desert environment.
The core habitat remains the White Sands Missile Range (WSMR), spanning a significant portion of the Tularosa Basin. The restricted access and size of the WSMR have been integral to the population’s success, providing a large, undisturbed area for reproduction and foraging. From this central location, the oryx have dispersed into adjacent areas, including the San Andres Mountains and the Jornada Basin, expanding their range across southern New Mexico. Population counts are periodically conducted using aerial surveys to generate estimates for management purposes.
Management Strategies and Harvest Control
The New Mexico Department of Game and Fish manages the oryx population primarily through controlled public hunting, which acts as the main form of population control. This system is necessary because the population continues to expand and has few natural checks in the region. Management goals are designed to keep the population within desired bounds. This mitigates ecological damage and conflicts with human activities, such as those on the WSMR.
The state employs a draw system for hunting licenses, dividing hunts into categories like once-in-a-lifetime trophy hunts, broken-horn hunts, and general off-range hunts. The number of permits issued, or the quota, is set based on the latest population surveys and management objectives. The annual harvest has reached over 1,500 animals in recent years. This framework balances the revenue and recreational opportunities generated by the species with the necessity of limiting its numbers.
Environmental Impact of a Non-Native Species
The establishment of a large, non-native ungulate like the oryx has generated socio-ecological concerns regarding the Chihuahuan Desert ecosystem. Oryx are generalist grazers whose diet includes native desert grasses, yucca, and mesquite bean pods. This puts them in direct competition with native herbivores such as mule deer and pronghorn for forage, especially during dry periods. Their foraging habits, particularly their preference for unencroached grasslands, may accelerate a landscape change known as shrub encroachment.
By focusing their grazing on remaining grass patches, the oryx contribute to grassland loss. Large herds can also trample native vegetation. Additionally, there is a risk of disease transmission to native ungulates, including the desert bighorn sheep.