Which of these is considered the most destructive invasive species in the United States:

  • The European Rabbit
  • Asian Carp
  • Starlings
  • Wild Hogs

Answer: Wild Hogs!!

You can frame discussions of invasive species in a variety of ways. When you talk about rapidly reproducing species like rats, starlings, or rabbits you can highlight the sheer number of them. When you talk about invasive waterborne species like zebra mussels and Asian carp you can talk about their ecological impact on waterways and the Great Lakes. Invasive plants can be framed in terms of the volume of land they’re conquering (like how the prolific and invasive Kudzu vine consumes over a hundred thousand acres of land a year).
But if you want to talk about pound-for-pound destructive abilities the title goes to an invasive species that, if you’re not from the southern or western United States, you might not even be aware of: wild hogs.
Sure rats might cause problems by chewing on water and power lines here or there, Asian carp might be shifting the ecosystem of the Great Lakes, and the vines slowly consuming Georgia and other Southern states are a huge nuisance, but they all (even collectively) have nothing on the feral hog populations exploding up out of the southern states.
Although feral hog populations have been with us since Christopher Columbus introduced them to the New World hundreds of years ago, their numbers have grown over the years and increasingly better animal husbandry of domestic hog populations has kept diseases from spreading to the wild populations (further protecting and bolstering their numbers). What’s so destructive about the wild hog population, you ask? Wild hogs breed prolifically and are relentless in their pursuit of food. Unlike a flock of birds that swoops down and picks a crop clean, however, hogs will stampede through forest and field alike using their highly adapted hooves and strong and elongated snouts to dig, and dig, and dig, for food.
Farmers in Texas routinely find enormous tractor-swallowing holes in their fields where the hogs have, if you’ll pardon the pun, gone wild digging for food. The hogs are opportunistic and will eat just about anything: a group of hogs can strip an entire field of rice, wheat, corn, melons, potatoes, you name it, clean in a night. Some farmers have even reported the hogs coming during the night after the first planting and systematically eating every seed or seedling out of every single row. The destruction isn’t limited to just farmland, however, the hogs uproot entire trees, trigger widespread erosion with their foraging, and ravage native plant species (which in turn makes it easier for hardier invasive species to take hold in the wake of the hogs’ handiwork).
Worse yet, feral hogs have been reported in 39 U.S. states and as far north as Canada and, to complicate the matter, there are no legal poisons that work on them and efforts to cull the herd through hunting (Texas has year round open season on hogs with no bag limit) have done little to stunt the growth of the hog population. Even in years when local populations are reduced by 50 percent or more the population springs back within two to three years after extensive thinning.
So while the rats and waterway clogging fish might have captured the public imagination when it comes to invasive species, the real powerhouses in the invasive animal world are the hogs doing hundreds upon hundreds of millions of dollars worth of damage across the U.S. every year.
Image courtesy of NASA.