There are invaders among us. Large and small, they have infiltrated and spread, displacing native inhabitants and upsetting the natural balance. The culprits are known as invasive species, and they pose a real and significant danger to environmental, economic and human health.
By: Elliot Ambrose, Georgia DNR Public Affairs Intern
The War on Georgia’s Invasive Species: Part I
Some have been here for years; others have only recently made an appearance. Even more have the potential to become problems in the near future. Whatever the case, invasive species can have wide-ranging and long-lasting impacts if not addressed.
One invasive that exemplifies this problem is the feral hog.
A prolific and destructive species, feral hogs have been in Georgia for centuries. In the last several decades, however, pig populations—and the cost of damages they cause—have skyrocketed.
The Pig Problem
Introduced by Spanish settlers in the 1500s, feral hogs have increased their range, and their impact, significantly in Georgia over the last 50 years. Spread in large part by people illegally moving them to other areas, the species now occupies more of the state than ever and is having a devastating effect on native plants and animals and their habitats.
According to Charlie Killmaster, state deer biologist with the DNR Game Management Section, feral hogs threaten some native species by excluding them from valuable food sources.
“It’s another big animal out on the landscape that’s requiring a lot of resources to keep going,” Killmaster said. “The fact that they can out-compete a lot of our native species is causing a problem.”
On Ossabaw Island, where feral hogs have flourished in near isolation for hundreds of years, the threat to native species is even more direct. In the early 2000s, hogs destroyed nearly 70 percent of loggerhead sea turtle nests laid on Ossabaw beaches. In a DNR effort started in 2006 with State Wildlife Grant funding, systematic shooting and trapping has shrunk the predation rate to 10 percent. But keeping it there requires relentless work.
“If we stopped hunting them, it would get out of control quick,” said Cody Elrod, a DNR wildlife technician in his sixth summer on Ossabaw.
Wild hogs can begin breeding at 6 months old and give birth to eight to 26 piglets a year.
Feral pigs will also eat the eggs of ground-nesting birds, including shorebirds, turkey and quail. As they search for food, wild hogs use their snouts and tusks to root through the soil, a destructive behavior that can severely impact native plant communities and reduce the total number of plant species in an area. Declines caused by extensive rooting can also lead to infestations by invasive plants such as Chinese tallow, particularly in wetlands and other sensitive habitats.
In addition to environmental impacts, feral hogs also wreak economic havoc, particularly for farmers. Hogs destroy acres of farmland by rooting up crops and recently planted seeds. Their foraging creates uneven, dug out areas that can damage large farm equipment. Feral hogs are also carriers of diseases, such as swine brucellosis and pseudorabies, which can be transmitted to domestic pigs.
The cost of the damage is uncertain, but a University of Georgia survey of landowners in 2011 estimated the total at more than $81 million.
Georgia’s Least Wanted
The voracious feral hog is just one invasive species causing concern in Georgia.
Known as “the seventh worst weed in the world,” cogongrass was documented at fewer than 10 sites in Georgia in 2004. By 2012, this Asian grass variety had spread to more than 600. Now covering 1.25 million acres of the southeastern U.S., cogongrass is more widespread than kudzu, the region and state’s most infamous invasive. Fortunately, all known cogongrass sites in Georgia have been mapped and treated.
A more recent arrival in Georgia, the emerald ash borer first appeared near Atlanta in 2013. The small green beetle native to Asia and east Russia is widespread throughout much of the Northeast, and has killed tens of millions of ash trees. The emerald ash borer is viewed as one of the most destructive forest pests ever seen in North America, making it a top priority for state and federal agencies.
Control efforts in Georgia are focused on containing the infestation, including through raising public awareness about how the insect is spread, typically through transporting contaminated firewood.
As is evident with the efforts to control feral hogs on Ossabaw, managing invasive species requires persistent effort. And because many exotic invasives spread rapidly and are difficult to eliminate once established, the focus is usually on management and control, rather than eradication.
There are a number of ways the public can help in the war on invasives. Learn to identify the invasive species found in your area to keep tabs on potential problems in your neighborhood. Take care to clean your gear and equipment before leaving outdoor areas and never release pets into the wild. When landscaping or gardening, consider choosing native plants instead of exotic varieties that may spread beyond your yard and put pressure on native species.
(Editor’s note: This is the first post in a multi-part series on invasive species in Georgia. Up next: Watch what you plant! Explore the benefits of “growing native” and how to avoid exotic invasive plants.)
Help with Hogs
Georgia lawmakers further relaxed restrictions on hog hunting this year, allowing for more options and opportunities to harvest wild pigs.
Hunters Helping Farmers, a private lands initiative by the Georgia Department of Agriculture and DNR, connects farmers and landowners with a pig problem to hog hunters in their area.
The USDA Animal and Plant Health Inspection Service offers the Feral Swine Damage Management Program, a national initiative to reduce wild pig populations and their impacts. The program is the first federally authorized feral hog management effort and involves coordination between federal, state and local agencies.
Key Offenders, Plus Some Lesser-Knowns
- Hemlock wooly adelgid: Native to Asia, this small, aphid-like insect feeds on the sap and inner bark of hemlock trees. First reported in Virginia in the early 1950s, it is now established in several eastern states and has affected more than 50 percent of the geographic range of the eastern hemlock.
- Chinese wisteria: Brought to the U.S. from China as a garden ornamental in the early 1800s, the woody vine is capable of reaching a height of 40 feet. This invasive displaces native vegetation and kills trees and shrubs by girdling them.
- Kudzu bug: This stink bug family member was discovered in the U.S. in October 2009 and has since spread through the Southeast. A native of India and China, it has become a nuisance pest in Georgia, damaging soybean crops and overwintering in houses.
- Cuban treefrog: With a wide diet and the ability to deter predators with noxious mucus, this large treefrog is highly adaptable and believed to have a detrimental impact on native species. First recorded near Savannah in 2009, Cuban treefrogs have established large colonies in Florida and are widely available for purchase as pets.
The Statewide Invasive Strategy
The focus of Georgia’s invasive species strategy is preventing the introduction of new invasive species and minimizing the spread of existing populations and their impact on native species, the economy and environmental and human health.
This goal is achieved through early detection and rapid response programs, cooperative management activities, and public outreach and education. The strategy also includes monitoring and research of invasive species to determine key management priorities, as well as designing and proposing legislative or regulatory measures.
The invasive strategy was called for in Georgia’s State Wildlife Action Plan, a comprehensive strategy guiding DNR and partner efforts to conserve Georgia’s native wildlife and natural habitats. That plan is being revised, yet will continue to emphasize controlling exotics.