(This story first appeared in the Summer 2014 Outdoor Reporter)
By Colleen Richardson, Special to New Mexico Wildlife Federation
As your eyes scan across the open range, the unmistakable snow-white rump of an antelope catches your attention. Their keen vision, sense of smell and speeds of more than 50 mph makes them a worthy adversary for hunters – particularly in New Mexico, where pronghorn records are set.
It’s never easy to draw an antelope tag, but odds could decline even further if the current drought continues much longer. Although adult pronghorn can weather the lack of moisture fairly well, fawn survival rates are showing signs of stress for a number of reasons, Department of Game and Fish officials say. If the drought deepens and adult numbers drop, hunters could see cutbacks in tags. On the other hand, a year or two of decent rain – and this summer’s monsoon rains are expected to be above average – could keep pronghorn numbers stable.
The American pronghorn antelope that grace the plains of New Mexico and much of the West is found only in North America, a true representative of western wildlife. Interestingly, it isn’t even closely related to any of the African antelope species.
Pronghorn antelope numbers were once estimated upwards of 40 million in the western prairie of North America, but overhunting and habitat loss during early settlement of the West were devastating. In New Mexico, pronghorn numbers were estimated at just 1,700 animals in 1912, the year New Mexico joined the Union.
Thanks to stronger laws and game management through New Mexico’s adherence to the North American Model of Wildlife Management, plus efforts by sportsmen and the state to rebuild populations, pronghorn numbers began to rise. With the advent of translocation efforts, pronghorn began to return to areas where they once thrived.
The current population in New Mexico is estimated at 45,000 animals, using fixed-wing aircraft surveys to estimate the population. Although antelope are found around most of New Mexico, the northeastern quadrant historically has the most robust populations and pronghorn numbers appear to be stable, said Stewart Liley, the Big Game Program manager for the Department of Game and Fish.
In the southeast and southwest, numbers fluctuate more because of drought, and there antelope numbers are down slightly from the long-term average, he said.
Adult survival is actually pretty good on average, but fawn survival is a concern, Liley said. A year or two of low fawn production is typically not a problem in the long-term health of a pronghorn population. “But if we see another year or two of this fawn production being suppressed and we may have to look at” reducing harvest levels, Liley said. “As long as we can get good fawn production every once in a while, however, that will help us out.”
Last year’s surveys found an overall fawn-to-doe ratio of 28-to-100, which is thought to be below the level needed to promote population growth.
Drought is driving the higher fawn mortality rates for a number of reasons, he continued. Precipitation provides better forage for pregnant does, which gives their offspring greater overall vitality.
Rainfall also provides critical protective cover for newborns. Because of their small size and inability to keep up with the herd within the first few days of life, does will nest their fawns in areas with high density grass cover to protect them from the elements and predators such as coyotes and eagles. Drought conditions can also lead to malnutrition and altered migration patterns that can have a small effect on population distributions.
Habitat improvement projects could mitigate some of the impact of drought, said Ryan Darr, who is managing the Department’s antelope program. Removing encroaching juniper, better grazing management, fencing modifications, targeted predator control and supplemental water sources could help give pronghorn populations an additional edge during periods of sustained drought.
Texas has seen its pronghorn population fluctuate due to various culprits including drought and predation, but also disease and parasites. Diseases recently studied in the Panhandle and Trans-Pecos regions, such as blue-tongue virus and epizootic-hemorrhagic disease, can cause large scale die-offs and severe impacts to the population.
One parasite of particular concern is the barber pole worm. More than 100 worms can be found in a host animal, living off the blood and consuming half a milliliter of blood per day. At that rate, it doesn’t take long for the animal to become anemic and die.
The long-term effect of this parasite comes from the eggs it produces and excretes though the feces of the pronghorn. Antelope are social animals and often congregate around common areas such as water tanks. With the spread of egg-infested fecal matter, other members of the herd can pick up the eggs during grazing and become infected themselves.
This parasite is common in areas where sheep and goats are grazed. “Sampling in New Mexico has revealed the barber pole worms in a few pronghorn; however, no population level impacts have been observed,” Liley said.
One challenge pronghorn face that sportsmen and ranchers can help overcome is the type and distribution of fencing across much of New Mexico. Many fences that separate land parcels are not wildlife friendly, specifically for antelope. Pronghorn seldom jump anything over 3 feet in height, preferring instead to go under, so a fence 4 feet or higher and with a bottom wire less than 12 inches above the ground can create a significant barrier to antelope.
State agencies and some landowners have begun to work together on “wildlife-friendly fencing,” rebuilding sections of fence to have 15 to 18 inches of ground clearance that allow easy access for pronghorn movement between pastures and properties.
Although other states have higher numbers of antelope, New Mexico has become one of the most popular states for antelope hunting. According to the 2014 Draw Odds Summary, more than 34,000 hunters applied for antelope tags in New Mexico, though only 1,851 tags were available to both resident and non-resident hunters through the public draw. Only about 30 percent of all available antelope licenses in New Mexico go through the draw – the remainder are given to landowners enrolled in the Antelope Private Land Use System, or APLUS.
Based on the number of Boone and Crocket entries, New Mexico ranks a phenomenal No. 2. More than 560 antelope taken in New Mexico meet the minimum requirement to be entered – 80 inches. But what produces a trophy animal? New Mexico generally has milder winters and longer growing seasons compared to northern states, thus providing better nutritional value to the forage – which eventually translates into mass, total length and size of prongs. Everything from soil type and annual precipitation to age of animal and genetics can play a factor in the development of a trophy animal.
The northeastern GMUs are the most popular to apply for and have the largest number of tags available to hunters. These units are also primarily privately owned, which presents both problems and opportunities to hunters. Under A-PLUS, a hunter applies through the public draw, and if successful is assigned to a ranch selected by Game and Fish. Enrolled ranches can sell their non-draw license authorizations. New Mexico Wildlife Federation calculates the odds of drawing an antelope tag at about 5 percent – roughly one hunt every 20 years.
Not every ranch enrolls in APLUS, but the Department in recent years has established a way for draw hunters to access areas of public land. The agency will essentially find large tracts of legally accessible public land with huntable populations of pronghorn, and declare it a “public land ranch.”
Pronghorn will forever be a unique and cherished resource for sportsmen and women in New Mexico. To ensure populations are sustainable for harvest, landowners, hunters and game management agencies must work together to ensure high quality habitat is provided in the form of proper grazing practices, wildlife friendly fences and adequate water supply. When multiple forces come together for the benefit of wildlife, the possibilities are endless.
