Nonnative Species

Nonnative, or exotic, species are those that are native to another areas but move into new areas, usually with some help from humans. They often cause negative impacts to native species, and in severe cases, to entire ecosystems. Big Thicket National Preserve has documented several nonnative species of animals and plants in the preserve, including fire ants and many plant species. By far the most problematic invasive animal species in the preserve is the feral hog.

 

Feral hogs

NPS Photo

Feral Hogs

Feral hogs are one of the most destructive nonnative animals found in the preserve, both in terms of their raw habitat-altering impact and the challenges to control them. The term “feral hog” applies to domestic hogs that were released or escaped to the wild, Eurasian wild boars introduced for sport hunting, and hybrids of the two. Brought to the United States by early explorers and settlers and first introduced to Texas in the 1680s, feral hog numbers have increased dramatically in the past decade. An estimated 2-3 million feral hogs range over the state of Texas.

Feral hogs are omnivorous and have voracious appetites. They compete with native wildlife for food, and can root-up large areas literally overnight. Feral hogs are known to eat acorns, tubers, fruits, insect grubs, carrion, amphibians, reptiles, eggs, birds, and arthropods (especially beetles) and can prey on the young of many mammals including white-tailed deer fawns. Because they can be carriers of a host of diseases and parasites such as brucellosis, tuberculosis, plague, and anthrax they also represent a health hazard to native wildlife, domestic animals, and humans.

The preserve is using a multi-pronged approach to address the issue of feral hogs. Learn more about feral hog control efforts, including how you can participate.

Feral Cats and Dogs

Stray or abandoned cats and dogs are also of concern in Big Thicket National Preserve. They may compete with native animals for food resources, or starve due to lack of hunting skills. Cats can be extremely efficient killers of birds, lizards, rabbits, and small rodents. Some feral animals may become aggressive toward humans. All of these factors are problematic for preserve visitors, preserve wildlife, and the stray animals themselves.

 

Giant salvinia, originally from Brazil, is a problem plant in Texas and the southeastern US.

NPS Photo

Plants

Invasive plants are among the greatest threats to the ecological integrity of the Big Thicket. The highly fragmented nature of the preserve, crossed by numerous pipelines, road corridors, and waterways, as well as the potential for invasive weed seeds to come from neighboring private lands, nearby urban areas, and from oil & gas production pads all have allowed several invasive plant species to gain a foothold in the preserve.

In recent years, the preserve has focused control efforts on Chinese tallow, Japanese climbing fern, golden bamboo, and trifoliate orange. The National Park Service's Exotic Plant Management Team, as well as volunteers, have assisted in this effort.

One of the most problematic aquatic plants found here is giant salvinia. It forms dense mats that block sunlight and decrease oxygen content in the water, harming fish and other aquatic animals; the mats can completely cover small bodies of water. New nonnatives recently found in the preserve include Chinaberry, kudzu, and coral ardisia. Water hyacinth, an aquatic invasive of particular concern, is prolific and is expanding in the waterways.