Waterbirds At Risk

Despite their value, or perhaps because of it, waterbirds have not always fared well at the hands of humans. In one case, the harm was irreversible. The last sighting of the Great Auk in 1852 heralded the extinction of this colonial waterbird species through direct hunting impacts. Fortunately, the mass destruction of egrets by market hunting in the late 1800s and early 1900s was stemmed in time, and in fact, led to the modern conservation movement in North America. Yet as illustrated by the crash of the Brown Pelican population in the Gulf of Mexico due to contaminants, waterbirds are still at risk due to human activities.

Some waterbirds continue to be threatened by direct impacts of human activities. Longline and gill net fisheries kill large numbers of seabirds through entanglement and drowning. Oil spills from ships and chronic bilge discharge sicken and kill hundreds of thousands of waterbirds. Impacts from exposure to pesticides and other chemicals, which caused population declines in Double-crested Cormorants and Brown Pelicans in the 1960s and 1970s, continue to threaten waterbirds in places throughout the Americas.

Food concentrated in aquaculture ponds and hatchery facilities attracts herons, cormorants, terns, and pelicans, and may result in illegal killing by distressed fish farmers. Citizens sometimes look upon waterbirds with disfavor when nesting or roosting congregations in urban and suburban environments conflict with aesthetic standards. Public disaffection with waterbirds, warranted or not, may be among their greatest long-term threats.

The habitats of waterbirds—the important sites on which they depend for nesting, feeding and wintering—are also at risk due to human related and natural threats. Hydrologic change of freshwater wetlands, degradation of coastal and marine habitats, introduction of exotic and invasive species, and depletion of the food base all adversely affect waterbirds.  Habitat loss and degradation can cause population declines.