Cumberland Island is the only barrier island in Georgia with feral horses. Despite their popularity with tourists, they have caused serious damage to the island’s native ecosystem.
- Horses trample and graze upon key plant species. This includes Spanish moss (Tilandsia usneoides) and smooth cordgrass (Spartina alterniflora), the primary plant of the marshland. This grazing reduces the density of grasses in the marsh, which are crucial for trapping and holding sediments. As erosion increases, the marsh is more severely affected by storms.
- They feed upon sea oats (Uniola paniculata), which provide stabilization for coastal dunes and provide nesting areas for a number of endangered and protected animals.
- Feral horses that eat hundreds of pounds of vegetation each year also produce an excessive amount of waste, which is unable to be cycled quickly enough into the ecosystem. Effects on the island’s fresh water supply have not been thoroughly studied, but island clam beds have been closed to public harvest because of waste. Water at the swimming beach is never tested, but is visible at the water line.
Their heavy weight and hooves compress and churn delicate marshland: the homes of fiddler crabs, mussels, and nesting shorebirds. Their presence alone can frighten birds from their nests, and their hooves decimate shorebird eggs.
Thriving in a non-native environment is difficult for these grassland mammals; their flowing manes and long-haired tails can be deadly in vine-tangled forests, where they are snared and held until death.
Open expanses of salt marsh may seem potentially hospitable, but the weight of a horse is distributed on four small points that offer very little support in its soft mud. Once a horse sinks belly-deep, escape is unlikely; the tide, however, is inevitable. Many have drowned, held fast by the mud.
The National Park Service does not produce annual reports on the horse population (including any encephalitis data), or offer any reports related to staff or visitor injuries. However, it does estimate the herd’s population hovers between 150-200 animals.
In 2016, the NPS did release a brochure to educate the public on some aspects of the horses.
The damage from feral horses is visible to the naked eye, if you know what you’re looking for. In fact, you’d be hard-pressed to find an ecosystem on the island that isn’t directly impacted by these animals. Learn how to identify it yourself:
- Horses have teeth on both their upper and lower jaws, so they ‘cut’ plants on branches, stems, or leaves. Look for clean cuts of vegetation in a vertical swath, over a broad area. You may also observe the ‘browse line’, which is a horizontal line of decreased vegetation at a consistent height – it will correlate with average horse height.
- Visitors commonly observe the island’s horses concentrated in marshland and beach areas. As grassland animals, they prefer wide open spaces; the result is the degradation of stabilizing marsh grasses and delicate dunes as they forage for food.
- Piles of dung cover the island from the moment you step off the ferry until you reach the beach. Besides the overall breathtaking beauty of the island, it’s possibly the most commonly-recalled memory by visitors.
The wild horses of Cumberland Island may be a romantic notion for visitors, but they threaten the very ecosystems that create it.
The National Park Service does not produce any reports on the horse population (including encephalitis), or offer any data related to staff or visitor injuries.
- Document your concerns and observations — share them with Wild Cumberland and the NPS.
- Demand the NPS document and manage the feral horse population with transparency and in accordance with their governing responsibility.