BEAUFORT, N.C. -- More than any other creatures, wild island ponies personify the rugged beauty of the sandy barrier beaches that line much of the East Coast.
Motels are named for them. They are a recurring decorative motif in restaurants. And tourists by the boatload venture out to watch as mares and foals walk along the water's edge and bend gracefully to crop the marsh grass, while stallions watch alertly from nearby dunes.
But a growing number of scientists say these scenes are not as benign as they seem. The horses are not existing with nature, the scientists say, but destroying it with every mouthful of the tender shoots they favor.
New research on barrier islands near here shows that grazing horses greatly reduce the amount and variety of island plants. And when the islands lose the plants, they can lose much of their ability to trap sand and defend themselves against erosion. The horses also cause trouble by trampling the soil, destabilizing the dunes, grazing on rare plants and by leaving droppings that alter the nutrient balance in the soil. By destroying the low-growing plants in the islands' maritime forests, they leave trees open to destruction through salt spray and wind.
The National Park Service has begun a three-year study to develop a management plan for horses on barrier islands in the Southeast. Initially, researchers will study horses on Cumberland Island National Seashore in Georgia, where earlier research showed that horses reduced above-ground vegetation by up to 98 percent, and Cape Lookout National Seashore and Cape Hatteras National Seashore, both in North Carolina.
Many researchers who have studied the issue have concluded that the several hundred horses on the islands do not belong there and say their numbers should be reduced by culling herds or other means, such as sterilization. Scientists at the Assateague Island National Seashore in Maryland are testing drugs that make mares temporarily infertile.
But, as a North Carolina report noted in 1990, "the horses of the barrier islands have a strong and emotional constituency."
Horses have lived on many of the islands since the 19th century or even earlier. Most biologists believe the ponies descended from horses left behind when settlers abandoned the islands or dumped there when they had lost their usefulness on mainland farms.