Winter’s coming for feral hogs, giant salvinia
Winter swings a cruel scythe over the natural landscape and the creatures on it, reaping swaths of the unprepared and unlucky, the too old and too young, too slow and too weak and even some who are none of these things.
This is true even in temperate Texas, where the darkest of seasons isn’t nearly as seemingly pitiless as in higher latitudes. But even here, so much of the landscape is stripped of most of its vegetative clothing and the rest is mostly dormant, ragged and bare, unable to provide cover or sustenance. With autumn’s bounty’s mostly long ago consumed, the promise of spring’s flush of renewed richness is weeks or months away. Even a short spell of cold, wet weather can prove fatal to exposed, hungry terrestrial and, sometimes, aquatic life.
Late winter can be, and usually is, a time of profound stress and vulnerability for so many pieces of Texas’ natural mosaic. And that includes some of the pieces that don’t belong there and whose absence would greatly benefit Texas, Texans and their native natural resources.
This is a good thing. Winter, especially late winter, can be an ally in the war against some of the invasive species that threaten and greatly damage the state’s native natural resources. Take two of the worst: Feral hogs and giant salvinia.
Winter — this one and the previous — has proven a blessing in a long-running battle to reduce the amount of giant salvinia plaguing more than two dozen of Texas’ inland waters and the life in them.
Caddo Lake now winning the war
Two summers ago, a stunning 6,000 acres — more than nine square miles — of 25,000-acre Caddo Lake were covered with a smothering mat of the alien aquatic plant. The picturesque, shallow, swampy, cypress-studded lake, which holds the most diverse fishery in the state, was suffocating under the covering created by the South American plant.
Salvinia, like so many non-native invasive species, has no natural controls in its invaded world — no insect, fish, animal or other native creature eats it. And with the ability to grow at astounding rates, salvinia can completely cover the surface of large areas of water.
That blanket quite literally chokes the life from the water beneath it. The mat prevents sunlight from penetrating the water, and submerged aquatic plants as well as phytoplankton lose the key ingredient for photosynthesis. They die, taking with them the oxygen that photosynthesis produces, with the bacterial process of breaking down the now-dead native submerged plants sucking even more dissolved oxygen from the water. Aquatic life — all of it, vertebrate and invertebrate, fish to crawfish, snails and insects — can’t survive without that dissolved oxygen. The mat of invasive plants quite literally smothers the life from the water.
Winter gave Caddo — and several other Texas waters — a break from this choking invasive. A pair of good freezes in early 2018 killed a large quantity of salvinia on some waters, Caddo included. Many of the tropical plants could not weather an extended period with temperatures below freezing.
Then winter weather, last year and again this year, produced another blow to the salvinia invasion. Heavy winter rains caused flooding on river and reservoirs, sweeping salvinia with it.
A recent survey of Caddo Lake showed the salvinia mat had been reduced to “just” 1,500 acres.
“We can thank Mother Nature for the cold snap and subsequent flooding that caused a massive decrease in giant salvinia on Caddo Lake and at our other infested East Texas lakes,” John Findeisen, who leads Texas Parks and Wildlife Department’s Inland Fisheries Division’s aquatic habitat enhancement team, said. “A hard freeze in January 2018 made a huge dent in the giant salvinia, freezing much of the plant material and loosening the dense mats. This was followed by high water inflows a month later, pushing the remaining giant salvinia to the open lake, where it was destroyed by wind and waves and washed up on shore.”
This winter has not proven as cold as 2018 was. But it has been much wetter. And that has helped to further reduce salvinia coverage on some inland waters as weeks-long sieges of flooding on rivers and reservoirs flushed the mats downstream. This winter’s high-water levels along the Trinity River — the lower section of the river has been at or above flood stage for most of the lpast three months — has swept much of what had been a growing salvinia infestation in the oxbows, sloughs and swamps along the Lower Trinity into Trinity Bay, dooming the plants.
Winter’s effects on salvinia give human efforts to try controlling the invasive plants an advantage they otherwise would not have. With acreage covered by the plants reduced, follow-up efforts — herbicide treatments and release of a new crop of salvinia weevils, a South American insect that feeds exclusively on salvinia — stand to have a better chance of controlling the invasive plants ahead of the warm-weather growing season.
Late winter also gives Texas hunters their best chance of the year to make inroads into the state’s pestilence of wild pigs.
Texas is awash in a sea of feral hogs, with as many as 3 million of the swine devastating the landscape, causing profound economic and environmental damage. The sweep of that damage is frightening and goes far beyond the tens of millions of dollars the pigs’ actions annually inflict on agriculture and other property. Not only do feral hogs compete — out-compete — native wildlife for space and resources, they wreak havoc on all manner of native wildlife through predation. They devastate amphibians and reptiles and are opportunistic predators of ground-nesting birds such as quail and turkey.
Feral pigs can be reservoirs of diseases that infect humans as well as ravage domestic swine. And their behaviors — their plundering of wild mast crops and their habit of tearing open large areas of ground through their rooting efforts — have a significant detrimental effect on the landscape. Studies have shown feral hogs reduce the diversity of plant life, especially woody species such as oaks, hickory, tupelo and other mastproducing trees in their range.
Perhaps even more disturbing, feral hogs’ actions, especially their rooting behavior, helps spread Chinese tallow trees, another invasive species that causesacute economic and ecological damage. Research indicates that tallow trees are twice as abundant in areas inhabited by feral hogs as they are in equivalent areas where the swine are absent.
Helping make feral hogs “absent” through hunting or trapping them can be most effectively accomplished during late winter. The season works against the swine and in favor of hunters.
As February arrives, winter has stripped much of Texas’ landscape. That forces the pigs to concentrate in or near areas holding what is left of decent cover that offers at least some protection from the elements. Places such as thick stands of young pines, yaupon or switchcane thickets, cedar ( juniper) breaks and swales in the lee of hills are magnets for sounders looking for a respite from winter’s chill and wet. They are a good place for hunters to start.
And when those feral hogs do move out of those refuges from winter’s cold grip, as they must, the lack of vegetative cover on most of the landscape leaves pigs more exposed and visible to hunters than during other seasons. The advantage to hunters is clearly seen through a rifle’s scope.
Feral hogs are much more likely to be active — moving — during winter. They are hungry. Very hungry.
While feral hogs are the ultimate omnivores and can subsist on even the most nutrient-poor forage, even they are hardpressed to find food during late winter. Autumn’s mast crop has been greedily devoured. Winter has shriveled most emergent plant life; the first flush of cool-season forbs is just starting to show. Even the reptiles, amphibians and other wildlife that make up about 10 percent of feral hogs’ diet are hibernating or otherwise sequestered in winter quarters and unavailable.
Hogs love a free meal
Feral hogs have to constantly scramble to find forage this time of year. So they are almost constantly on the move, hunting for something to eat.
That constant movement increases chances a hunter will encounter them. And hunters can greatly increase the odds of such encounters by giving pigs a reliable food source.
Throughout the year, baiting — using battery-powered automatic feeders filled with shelled corn and fit with a timer that distributes a free meal — is an almost universally used method of drawing feral hogs to an area where they can be shot or trapped. But the tactic can be particularly effective during late winter, when the swine are desperate for calories.
Corn-spewing feeders set in an area holding hogs are sure to draw traffic. Hunters can set feeders to distribute corn soon after sunrise or an hour or so ahead of sunset, set up in a blind within easy rifle range and stand a good chance of seeing pigs.
To increase odds of success, set a remote-sensing game camera to monitor the feeder or travel paths to and from the feeder. The cameras record the time photos that are taken of animals visiting the feeder or traveling a trail. Once hungry hogs find a feeder (and they will), they typically will visit it daily at the same general times. A camera can tell a hunter what time of day or night; feral hogs are one of the few animals that can legally be hunted at night when the hunter has the best odds of success.
That success — killing feral hogs — produces multiple benefits. Not only has the hunter enjoyed time afield but also has collected the makings of many fine meals; feral hogs provide wonderfully delicious protein. But even more beneficial, that hunter has removed an incredibly destructive invasive species from the landscape.
Late-winter hunting of feral hogs is not a solution to the feral-hog problem facing Texas, just as the increasingly infrequent sieges of significantly cold temperatures will not rid the state’s water of the scourge of giant salvinia. But both are good reasons to look at late winter in a bit more positive light — something that can be hard to do, otherwise.