“The hunters grew up reading hunting magazines that said you needed brush, and you do need some,” says Matthew Poole, a wildlife biologist with Texas Parks & Wildlife Department (TPWD). “But our deer are getting bigger on open country.”
Poole is optimistic that, over time, cultural attitudes will catch up with the science. That science is dispelling some old notions and offering new opportunities to manage lands for both wildlife and cattle.
Poole’s research lab is the 28,000-acre Matador Wildlife Management Area near Paducah, Texas. He and manager Chip Ruthven try to operate the area like a cattle rancher who has a bias toward his wildlife enterprise.
Lessees’ cows rotationally graze the area, leaving enough grass for nesting cover. Ruthven added fencing and windmills, plus solar pumps and tanks to improve grazing distribution. He and Poole deal with brush.
Research here is landscape scale, and the land teaches some lessons. “We hope to demonstrate that livestock can be used to manage for wildlife,” Poole says. “Cows have the same effect as bison in pre-European settlement.
“If we didn’t have cows, the grasslands would choke themselves out. These grasslands produce more biomass in a year than what can be decomposed naturally.”
Pre-European settlement is the habitat model the managers seek to emulate. That benefits all native wildlife species. One hurdle has been mesquite that’s invaded the grasslands, creating mesquite dominated woodlands.
For that, the managers in 2004 turned primarily to aerial applications of herbicide with follow-up measures to maintain control. In recent years, they’ve used Sendero® herbicide, touted by Corteva Agriscience™ for its efficacy and its selectivity on mesquite and little else.
Poole estimated the first application of Sendero on the wildlife management area in 2012 controlled at least 95 percent of the target mesquite. Then he learned a timing lesson with one that yielded about 55 percent control.
“We sprayed after the recommended time,” Poole admits. “I thought soil temperature was everything, but that timing after bud break is important.”
Still, mesquite spraying largely has accomplished TPWD’s first goal: Grow grass for cows and allow hoof action to disturb the soil and bring in forbs. Poole and Ruthven have targeted areas where mesquite canopy covers 60 percent to 90 percent of the ground.
What the herbicide hasn’t controlled is almost as important as what it has. Some wildlife managers worry about “forb shock” — killing broadleaf herbaceous plants that are preferred by wildlife.
“In Year 1 after application, we do see a little forb shock on sunflower and ragweeds,” Poole says. “But there aren’t many desirable forbs in the understory of this dense mesquite. If there is any collateral forb shock, it’s temporary.
“From a wildlife standpoint, given a choice between live mesquite or dead mesquite and forb shock, I’d take dead mesquite and forb shock every time. Forbs will come back.”
Among woody plants, bumelia and hackberry valued by wildlife survived the mesquite spraying. The hackberries initially did turn yellow and brown, Poole says, but after a year, they seem unaffected.
How grasses respond to brush control is driven by weather, Poole says. In his experience, given adequate rainfall, plains bristlegrass has dominated uplands the next year. Little bluestem has come in later. Creek bottoms have responded in big bluestem, Indiangrass and switchgrass. Those grasses provide excellent livestock grazing, nesting cover for birds and fawning cover for deer.
With grazing, Poole says, Engelmann daisy and dayflower have come into sprayed areas. Both forbs are valued by deer and cattle. Dayflower seeds are relished by quail.
Grass response also provides fine fuel for a prescribed burn. A winter burn three to seven years after application has reduced the standing dead brush and woody litter. It’s also opened the site for more sunlight to allow native grasses and forbs to thrive.
With adequate fuel, burning at five- to seven-year intervals tends to suppress new mesquite growth in the Rolling Plains, Poole says. Under normal rainfall, one growing season of grazing deferment typically provides that fuel. Burning helps to maintain a savannah appearance — a mosaic of brush and open country.
Where repeated burns failed to remove standing dead trunks of sprayed mesquite, Poole tried knocking some down with an aerator pulled by a bulldozer. The old snags had provided a perch for hawks and other quail predators.
It worked best to wait at least three years after spraying for wood rot to set in —“Easier on equipment,” Poole says — and then install another burn. The follow-up burn reduces woody litter that otherwise makes it hard to even walk through a pasture, he says.
Don’t take an aerator or roller chopper to live mesquite, Poole advises, or it resprouts with many more stems. Along with mesquite control, the managers adjusted hunting on the area to improve buck-to-doe ratios to about 1 to 2 for whitetails and 1 to 4 for mule deer. Over time, deer body sizes and antler growth have increased. Use of preferred browse now is at a healthy level. Cows continue to graze.
"You can have a successful cow-calf operation and still have wildlife," Poole concludes.
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