Once-exotic antelope blamed for spread of cattle fever tick

The nilgai, a once-exotic antelope imported from Asia for zoos and let loose for trophy hunts on Texas ranches, are now being blamed for spreading the potentially devastating cattle fever tick the farthest into the U.S. interior in decades, possibly since it was declared eradicated in 1943. The Laguna Atascosa National Wildlife Refuge in lower Cameron County, about 2 miles north of the Mexican border at the southernmost tip of Texas, is being called ground zero for infested nilgai and white-tailed deer, which also are hosts. The park came under quarantine after the tick was found on the carcasses of hunted game in 2014. While the U.S. has strict rules requiring infected animals to be quarantined and treated to keep the ticks from spreading, Mexico does not. And the nilgai, cattle and other hosts for the nefarious fever tick roam unchecked across the border. The situation is especially grave because the animals are free-ranging and compromise ongoing eradication efforts such as systematic treatment or moving cattle out of infested pastures. According to the U.S. Department of Agriculture, an extended tick outbreak could cost U.S. ranchers and the broader economy more than $1.2 billion in extermination expenses and lost revenue from diseased animals. It's estimated that 70 percent of white-tailed deer and nearly 70 percent of nilgai on the refuge are infested, prompting officials to require that animals killed by hunters be tested and skinned on site, freezing the heads that are kept for mounting for 24 hours to kill the ticks. In the last year, the U.S. Department of Agriculture has contracted with helicopters and sharp shooters for aerial attacks that have so far killed about 200 of the nilgai. More aerial harvests are planned for the nilgai, refuge manager Boyd Blihovde said. "We've already done in my opinion quite a lot and we're going to continue do our part whenever we can," he said. But the damage may already have been done. Without natural wildlife predators, the nilgai population has exploded in South Texas, and female nilgai have been known to migrate as much as 30 miles. Neal Wilkins, CEO of the East Foundation, said 27,000 acres of the Foundation's 200,000-acre ranch in South Texas are under quarantine because the parcel is adjacent to an infested property...more