How Invasive Species Threaten Habitat

Removing Invasive Plant Species

Each year in America, more than 3 million acres are lost to invasive weeds -- an area equal to a strip of land two miles wide stretching from coast to coast. These weeds and animals like rats and feral pigs are not just wrecking vacant lots and dusty roads inhabited only by tumbleweed. Invasive species are choking out and destroying some of America's most valuable bird and wildlife habitat. In fact, invasive species are a primary threat to America's 94 million acre National Wildlife Refuge System as well as Audubon Important Bird Areas (IBA) across the country.

Invasive Species Threaten America's Wildlife Refuges

Wildlife refuges provide critically important habitat for America's birds and wildlife. Unfortunately, many of America's wildlife refuges are succumbing to a suffocating attack by invasive species.

According to the Fish and Wildlife Service, invasive species have become the single greatest threat to the Refuge System, causing "widespread habitat destruction" and "contributing significantly to the decline of trust species."

More than 250 wildlife refuges have been infested by invasive species that choke out, devour, and destroy native birds, wildlife, and their habitat.

More than 8 million acres of habitat within the Refuge System are infested with invasive weeds, including some of the System's most valuable habitat for birds and wildlife.

For example, the highly invasive Chinese tallow tree, which shades out native grasses and transforms grasslands, prairies and brushlands into tallow woodlands, has destroyed more than 55,000 acres of bird and wildlife habitat on Aransas National Wildlife Refuge in Texas. Millions of birds representing nearly 400 species funnel through this area at the base of the Mississippi Flyway. The open grasslands being destroyed by Chinese Tallow are important stopover habitat for thousands of Neotropical migratory songbirds, as well as the hunting grounds of the WatchListed Short-eared Owl.

Wildlife Refuges Provide Critically Important Habitat for Birds

The National Wildlife Refuge System is comprised of more than 540 land units spanning a vast geographic range encompassing more than 94 million acres. Within this area can be found nearly every major habitat type or biome in America: deserts, forests, tundra, great rivers, vast marshes, swamps, prairies, estuaries, coral reefs, and remote islands.

More than 700 species of birds can be found nesting, breeding, and wintering within the protected confines of the Refuge System. Particularly important to migratory birds is the System's extensive wetlands habitat, located strategically along the four major North American migratory flyways. These refuges are used as stepping-stones for millions of migrating birds each year as they fly thousands of miles south for the winter and return on their northern migration in spring. St. Marks National Wildlife Refuge in Florida, for example, protects 40 miles of coastline along the Gulf of Mexico supporting significant populations of a great variety of aquatic birds, including wading birds, shorebirds, and waterfowl. The coastal hammocks and upland forests of the refuge support Neotropical migrant songbirds. Longleaf pine flatwoods support breeding populations of endangered Red-cockaded Woodpeckers and wintering populations of the imperiled Henslow's Sparrow.

Dozens of wildlife refuges were established expressly for the conservation of threatened and endangered birds, such as the California Condor, Golden-cheeked Warbler, Greater Prairie Chicken.

Invasive Species Threaten Important Bird Areas (IBAs)

Audubon, as the Partner Designate for BirdLife International is working to identify a network of sites that provide critical habitat for birds. This effort known as the Important Bird Areas Program (IBA) recognizes that habitat loss and fragmentation are the most serious threats facing populations of birds across America and around the world. By working through partnerships, principally the North American Bird Conservation Initiative to identify those places that are critical to birds during some part of their life cycle (breeding, wintering, feeding, migrating) we hope to minimize the effects that habitat loss, and degradation have on bird populations. Unless we can slow the rapid destruction and degradation of habitat, populations of many birds may decline to dangerously low levels. The IBA program is a global effort to identify areas that are most important for maintaining bird populations, and focus conservation efforts at protecting these sites.