Invasive species pose a significant threat to ecosystems across North America. These non-native organisms can cause extensive damage to the environment, economy, and even human health. Often introduced accidentally or intentionally by humans, invasive species outcompete native species, leading to biodiversity loss and ecological imbalance. Here, we explore eight invasive species that wreak havoc across the continent.
Feral Swine (Sus scrofa)
Originating from parts of Europe, Asia, and North Africa, feral swine were introduced to the U.S. by European settlers in the 1500s for food and later for sport hunting. These destructive creatures, estimated to number at least 6 million in 35 states, cause extensive damage to agriculture, natural resources, and property. Feral swine root through fields, destroy crops, and degrade habitats, making them one of the most detrimental invasive species in North America.
Burmese Pythons (Python bivittatus)
Imported for the exotic pet trade, Burmese pythons were released into Florida’s wilds and rapidly established populations, particularly in the Everglades. These massive snakes, which can grow over 20 feet long, decimate native small mammal populations and disrupt the ecological balance. The absence of natural predators and the pythons’ high reproductive rate have exacerbated the problem, making control efforts extremely challenging.
Domestic Cats (Felis catus)
Introduced by European settlers as pets, domestic cats have become a destructive invasive species, killing billions of birds and mammals annually. Despite their popularity as pets, their impact on native wildlife has sparked controversy. Free-roaming and feral cats hunt a wide variety of species, leading to significant declines in native bird and small mammal populations, and contributing to the extinction of some species.
European Starlings (Sturnus vulgaris)
Originally introduced to North America by Shakespeare enthusiast Eugene Schieffelin, European starlings have become a widespread nuisance, destroying crops and outcompeting native species. These birds, recognizable by their dark plumage and iridescent sheen, form large flocks that can devastate agricultural fields and displace native birds from nesting sites. Their adaptability and aggressive nature make them a formidable invasive species.
Nutria (Myocastor coypus)
Brought to the U.S. for the fur trade, nutria have spread across the country, causing extensive damage to crops, natural resources, and infrastructure. Described as a cross between a beaver and a sewer rat, these rodents are prolific breeders and voracious eaters. Nutria burrow into levees and dikes, weakening flood control systems, and consume vast amounts of vegetation, leading to erosion and habitat degradation.
Asian Carp (multiple species)
Imported to the U.S. in the 1970s for various purposes, Asian carp have invaded waterways across the country, outcompeting native fish for food and habitat. With some species capable of eating up to 100% of their body weight daily, they pose a significant threat to aquatic ecosystems. Their rapid reproduction and aggressive feeding habits disrupt food chains and alter habitats, making them a critical concern for fisheries and conservationists.
Gypsy Moths (Lymantria dispar)
Accidentally introduced by French artist Étienne Léopold Trouvelot in the late 1860s, gypsy moths have spread throughout the northeastern U.S., defoliating millions of acres of trees and shrubs. These voracious pests pose a threat to forests, as their larvae consume the leaves of over 300 species of trees and plants. The defoliation weakens trees, making them more susceptible to disease and other stressors, which can lead to widespread forest decline.
American Bullfrog (Lithobates catesbeianus)
While native to large parts of North America, the American bullfrog has been introduced to new areas for food purposes, leading to disruptions in local ecosystems. These large frogs prey on native amphibians, contributing to declines in amphibian populations. Their voracious appetite and broad diet allow them to outcompete and displace native species, causing significant ecological imbalances.
