It's 5000 BCE in the verdant swamps of North America, and this young deer has no idea it’s being hunted. Suddenly, an alligator hurtles out of the water at almost 50 kilometers an hour, locking its jaws around its prey and swinging wildly in a signature move known as the death roll. This deer never stood a chance, but then, nothing in this region can compete with this apex predator. These alligators easily devour the birds, turtles, and small fish living in what’s known today as Everglades National Park. But despite ruling the swamp for millennia, the last 500 years have brought deadly new predators that challenge the alligators’ reign. And the origins of these international invaders are just as unexpected as their impact on the Everglades.
We tend to think of swamps as hostile landscapes since they’re overflowing with plant and animal life. But all this biodiversity makes these environments vital to regional food webs. And the Everglades are no exception. The park's subtropical climate can support species from around the world, and its borders are full of ecotones— transition areas between habitats— that connect the region’s freshwater prairies, rocky pinelands, mangrove forests, and more. Human activity has made the region even more biodiverse, developing Florida into a major port that welcomes countless human and non-human migrants.
In the 1500s, Spanish colonizers brought wild boar to the area, which quickly multiplied and uprooted the wetlands. They devoured alligator eggs and spread European parasites to local panthers. Then, in the 1800s, Florida’s shipping industry exploded, bringing all manner of new invasive species. Brazilian peppertrees blocked out the sun, water hyacinths clogged the rivers, and brown anole lizards upset the food chain. Alligator populations mostly endured this onslaught, but in the late 19th century, human intervention kicked things up a notch. Government and business officials wanted to turn the Everglades into farmland and began building canals to drain the swamp. They also planted non-native trees which crowded out the plants local birds relied on for food and shelter, which in turn limited the alligators’ supply of prey.
Interventions like this wreaked havoc on the Everglades for decades, until a conservationist named Marjory Stoneman Douglas finally came to their defense. In 1947, Douglas published a landmark book explaining that the Everglades were not only a unique and precious ecosystem, but that the region’s most fearsome residents were actually vital to sustaining it. During the wet season, alligators are constantly shaping the muddy landscape, drawing lines with their bodies and digging holes with their snouts, claws, and tails. In the dry season, these indentations become essential watering holes and firebreaks, maintaining and protecting the swamp’s other residents.
In the wake of Douglas’ book, Everglades National Park was established to formally begin protecting the landscape and its scaly stewards. But outside the park, conditions were brewing for the most dangerous invasion yet. Over the next 40 years, the exotic pet trade brought parakeets, iguanas, and relatives of piranhas to the region. In the 1990s, Burmese pythons became a cheap, popular pet for many Floridians. Some snake owners released their pets into the wild when they grew too large. But the python population really exploded in 1992 when a hurricane destroyed a breeding facility and released countless snakes into the wild. Since then, pythons have been connected to a 90% decrease in some local mammal populations, decimating the alligators’ food supply. And with help from other invasive reptiles like black and white tegus— giant lizards who devour alligator eggs— these snakes have made a serious play for the top of the local food chain.
Today, Florida ranks among the regions with the most invasive species in the world. Some researchers suggest hunting these invaders down, while others recommend bringing in yet more creatures to balance the scales, such as releasing insects to eat invasive plants. It might seem absurd to try solving this problem with more foreign fauna. But perhaps a new arrival could fight invaders and feed the alligators— giving them the boost they need to reclaim their ancient home.
