RICK KELLEY, Staff Writer
RIO HONDO — In the thorn scrub and patchy grazing land east of this city, an experiment has ended and a real-world project has assumed its place.
An innovative program which may save nilgai antelope in the Rio Grande Valley from helicopter culling in the war against the cattle fever tick has moved from a pilot project to the installation of 150 motion-activated sprayers in the field.
Six private ranches here, totaling 40,000 acres of prime nilgai habitat, are the venues to spritz nilgai bellies and legs with water containing billions of microscopic nematodes which kill cattle fever ticks.
“We’ve been able to prove that we can spray nilgai, and we know that the nematodes kill the tick, but what we don’t know is, when the whole thing comes together, can we really eradicate the tick on nilgai?” said John Goolsby, a U.S. Department of Agriculture tick expert who is overseeing the project.
They’re back
South Texas is in the middle of an irruption of the cattle fever tick which is spreading north from Mexico, where it is endemic.
The fever ticks can carry a disease fatal to cattle called babesiosis, which has been a potentially catastrophic threat to ranchers and to Texas’ $12 billion-a-year beef industry.
A huge multi-state effort to eliminate the cattle fever tick in the United States early last century was a success by 1943, but ticks from Mexico periodically push northward into South Texas.
A permanent quarantine zone was established along the Rio Grande and extends 500 miles from Brownsville up the Valley in hopes of detecting and containing any cattle fever tick spillover from Mexico.
All of Cameron and Willacy counties are at present in a temporary cattle fever tick quarantine zone.
Locals, feds partner
The work here in eastern Cameron County is a partnership between Las Huellas, a local nonprofit conservation organization, the federal government and the Caesar Kleberg Wildlife Research Institute at TAMU-Kingsville. Funding comes from Las Huellas and congressional dollars allocated for emergency cattle fever tick research last year.
Las Huellas, or “the tracks” in Spanish, began and still continues its mission of restoring wild turkeys to the Rio Grande Valley. It has expanded now to the preservation of nilgai, a prized game animal native to South Asia which was brought to Texas by the King Ranch in the 1930s.
“We decided we needed to evolve,” said Sam Manatt, a Las Huellas member who owns one of the six ranches on which the new nilgai spraying program will operate.
Setting the ambush
Last week, a crew from the Caesar Kleberg institute was busy installing some of the 150 sprayers which will be installed at fence crossings on the six ranches.
Under a mesquite tree, the nilgai have carved out a hole underneath the fence separating one of the ranches from a national wildlife refuge on the other side, and were using the crossing regularly.
“If it was three-strand barbed wire, they might be crossing anywhere,” Goolsby said looking down at the deep tracks of nilgai hooves at the muddy crossing. “But if you have this net (fencing), it’s really good for holding cattle in and if you have horses they don’t get cut. Maybe a hog starts it, the nilgai get underneath there with its full strength, and just pops it on up.”
Carly Barbera works for the Caesar Kleberg institute and was part of the team installing the sprayers. She says she graduated from college with a biology major a couple of years ago, and then signed on in Kingsville.
“I know the cattle fever tick is a huge problem in the area, so we definitely have got to deal with it now,” she said. “It’s been really fun to learn this methodology, to learn a little bit more about the nematodes.”
Helicopters, cowboys
The nematodes are, coincidentally, native to Cameron County. The tiny worms are raised commercially and come in a cake-like block — billions of them. Valley and Florida citrus growers also use them to fight root infestations.
But spraying a nilgai is one thing. Finding out if what you’re doing is working is another.
“The next step is we capture the nilgai and we put the ear tags on them. when we capture the nilgai we’re going to scratch and do the count, any ticks on there I’ll count them and pull them off, but count them to see how many the nilgai have and then come back a month later and we’ll scratch them again,” Goolsby said. “Capture them and put some satellite collars on them.”
Goolsby makes it sound easy, but capturing a nilgai — cows weigh about 220 pounds and bulls up to 550 pounds — can be dicey.
“They’re in specialized helicopters that have these big net cannons,” Goolsby said. “They’re like right up, they’re not real low either, and BOOM! They explode that net right onto the nilgai.”
“Then they get the cowboys to go in there,” Manatt said.
A blindfold is put on the animals to try to keep them calm, and then their teeth are inspected to age the big antelope, and then they are scratched for ticks, which are collected.
“We’ll come back again with the helicopter and say, ‘Let’s look for that purple and yellow tag,’ and we’ll capture them again,” Goolsby said. “They should have zero or fewer ticks on them the next time.”
If it works here, Goolsby says the plan is to then expand the spraying program to all of Cameron and Willacy counties, which would amount to an additional 60,000 acres.
New discoveries
Already this project has caused upheaval within the cadre of nilgai experts.
The initial motion-activated sensors were set up at communal latrines where nilgai gather to do their business. Scientists were in agreement these communal dung heaps probably give nilgai some kind of evolutionary advantage against their age-old nemesis, the Bengal tiger.
It turns out the science was unsettled.
A TAMU-Kingsville graduate student hired by Las Huellas to study DNA samples taken from these dung heaps found these were not communal latrines at all.
“Now we know latrines are only single bulls, sometimes two bulls, but almost always single bulls,” Goolsby said. “Nobody knew that until Las Huellas funded that study. Before this was figured out, every single person in South Texas would tell you it was a common latrine.”
Problem was, the first prototype nilgai sprayers were set up to take advantage of nilgai congregating at those latrines, but instead of spritzing a whole herd with the nematode-laced water, they were getting only a bull or two.
“It turns out there are lots of good fence crossings, there are rally good places where nilgai concentrate,” Goolsby said. “These sprayers are designed to activate right at the fence crossing.”
New discoveries
Already this project has caused upheaval within the cadre of nilgai experts.
The initial motion-activated sensors were set up at communal latrines where nilgai gather to do their business. Scientists were in agreement these communal dung heaps probably give nilgai some kind of evolutionary advantage against their age-old nemesis, the Bengal tiger.
It turns out the science was unsettled.
A TAMU-Kingsville graduate student hired by Las Huellas to study DNA samples taken from these dung heaps found these were not communal latrines at all.
“Now we know latrines are only single bulls, sometimes two bulls, but almost always single bulls,” Goolsby said. “Nobody knew that until Las Huellas funded that study. Before this was figured out, every single person in South Texas would tell you it was a common latrine.”
Problem was, the first prototype nilgai sprayers were set up to take advantage of nilgai congregating at those latrines, but instead of spritzing a whole herd with the nematode-laced water, they were getting only a bull or two.
“It turns out there are lots of good fence crossings, there are rally good places where nilgai concentrate,” Goolsby said. “These sprayers are designed to activate right at the fence crossing.”
