Waterbird Conservation: Issues and Answers
For conservation goals to be identified and accomplished, wildlife managers require data on species’ population sizes and trends, and information on threats to population viability. Somewhat dauntingly, waterbirds are among the toughest to monitor of all birds. Seabirds spend most of their lives at sea, and most shorebird species breed in the Arctic and move quickly across the continent, in large groups that are difficult to count, to and from southern wintering areas. Many waterbirds that nest in human-occupied areas do so far from roads, and many waterbird species are secretive outside of, as well as during, breeding seasons. Yet recent efforts by people working on behalf of waterbird protection have begun to shed light on the lives of, and many of the conservation threats facing, North American waterbirds.
Most waterbird declines are a function of human-mediated habitat loss:
A Piping Plover predator-proof enclosure. Photo by Fred Atwood
Many waterbirds exhibit breeding site fidelity - they return to breed in the same areas, often wetland habitats, year after year. They are thus vulnerable to habitat changes and other local threats to survival and reproductive success.
The land area that comprises America’s “lower 48” states contained an estimated 221 million acres of wetlands in the 1780s. After 200 years of draining, filling, dredging, leveling, and flooding, only 104 million wetland acres remain – a loss of more than half. This is equivalent to losing 60 acres of wetlands every hour between the 1780s and 1980s (Dahl 1990).
Each year, approximately 1.2 million acres of cropland, pastureland, and rangeland – potential wildlife habitat - are lost to development (Goodbody 2005).
Waterbird populations are negatively affected by other forces, as well. Unfavorable weather patterns, disease organisms, and predation pressure have all compromised survivorship and breeding success. Yet the direct and indirect effects of human behavior are more lethal. Humans destroy and degrade waterbird habitat – lakes, ponds, river and stream systems, wetlands, estuaries, oceans, and intertidal areas, and the associated terrestrial habitats of all – in myriad ways.
Off-Road Recreational Vehicles on Plymouth Beach. Photo by Cary Wolinsky
In the 20th century:
- Human development and use of beaches for recreation, conversion of estuaries into marinas, oil-related activities, fishing and agricultural practices, and water diversion and impoundment have permanently altered breeding, roosting, and foraging habitats, and the population dynamics of waterbird prey species.
- The introduction into waterbird habitats of human-commensal predator species (predators that exploit or benefit from human presence, e.g., cats, rats, and crows), invasive plant species, pollution, and toxins has caused widespread mortality and reduced reproductive success.
- The long-term effects of human-mediated climate change are just beginning to unfold. Global warming has already been documented to be associated with changes in population size, the timing of reproductive activities, migratory patterns, and poleward shifts in the distribution ranges of bird species. Global warming will undoubtedly result in the loss of shorebird breeding habitat in the Arctic.
The diversity of ways in which humans affect waterbirds is matched by the ways in which those effects are manifested. For example:
Common Terns over Pond Island Lighthouse. Photo by Steve Kress
Prior to the federal banning, in 1991, of the use of lead shot in hunting, thousands of tons of lead were deposited annually into lakes, marshes, and estuaries – about 6,440 pellets per bird bagged (Eisler 1988). Currently, 2,700 tons of lead sinkers are manufactured each year in the U.S., as are 400-550 tons in Canada (Sanborn 2002). Presumably, much of this represents replacements for sinkers lost during fishing. Many waterbirds ingest the smaller sinkers to use as grit in their gizzards, and the lead within them is released as the sinkers are ground along with sand and rocks. In New England, lead poisoning is the greatest source of adult loon mortality and accounts for approximately 50% of all deaths (Sanborn 2002); 64% of Common Loon carcasses from New Hampshire, and 44% of those from Maine, had ingested fishing sinkers (U.S. Environmental Protection Agency [EPA] 1994). Scientists consider levels of 5-6 ppm of lead in the liver to be toxic in waterbirds, and the levels in four loons that had lead sinkers in their gizzards ranged from 5.03-18.0 ppm (EPA 1994).
- Many seabird populations are imperiled because of numerous anthropogenic factors, including introduced predators on islands, oil spills, ocean pollution, human overfishing of seabird prey populations, and entanglement in driftnets and longlines. Longline fisheries cause high seabird mortality; a single vessel may deploy 35,000 baited hooks on lines that extend up to 60 miles (American Bird Conservancy [ABC] 2006a). Hooks are baited with whole fish or squid, and foraging seabirds drown upon becoming hooked. Hundreds of thousands of seabirds are killed each year because of longline fishing (Worldwatch Institute 2003).
- Global warming is expected to reduce the number of ducks in the north-central U.S. by more than one half in the next 50 years – from approximately 5 million today to between 2.1-2.7 million in 2060 (EPA 1999). Thousands of ponds in the prairie pothole region are likely to dry up because of warmer temperatures and more frequent droughts. While accounting for only 10% of North American waterfowl breeding habitat, the ponds in this region are responsible for the production of 50-80% of the continent’s ducks (EPA 1999). These “potholes” also provide important stopover habitat during waterfowl migration.
And yet, advances in waterbird protection and conservation continue to be made, in many different ways. For example:
- Ninety-eight cents of every dollar you spend on The Migratory Bird Hunting and Conservation Stamps, often called the 'Duck' Stamp, goes directly into purchasing habitat for protection in the National Wildlife Refuge System. Since 1934, the Migratory Bird Hunting and Conservation Stamp program has raised over $700 million to protect more than 5.2 million acres of habitat (U.S. Fish and Wildlife Service 2005).
- In response to the precipitous declines of several well-known birds during the 1950s and 1960s – the result of ingestion of DDT and other organochlorine pesticides, and their lethal effects on eggshells – pressure to protect America’s imperiled species mounted. The Endangered Species Preservation Act was passed in 1966, modified in 1969, and became the Endangered Species Act (ESA) in 1973 (ABC 2006b). The ESA, which provides for the conservation of species that are endangered or threatened with extinction (and includes the ecosystems on which they depend), may be the most important piece of conservation legislation ever passed. By encouraging States with financial assistance and incentives, conservation programs that meet national and international standards have been developed and maintained. Many waterbirds have benefited from ESA protection, and the population sizes of several species have increased since listing, e.g., Wood Stork, Snail Kite, Bald Eagle, Clapper Rail, Sandhill Crane, Whooping Crane, Piping Plover, and California Least Tern. A couple of waterbirds have recovered and been delisted, e.g., the Brown Pelican and Aleutian or Cackling Canada Goose (ABC 2006b).
- In 1986, the Emergency Wetlands Resources Act of 1986 was enacted to promote the conservation of wetland habitats across the U.S. Between 1986 and 1997, the net loss of wetlands across the lower 48 states was 644,000 acres (approximately 58,500/year), a rate that is 80% lower than the rate of wetland loss during the 1970s and 1980s (Dahl 2000).
- U.S. farmers and ranchers have contributed hugely to wetlands conservation in recent years: approximately 263,000 acres of agricultural wetlands were protected or restored from 1997-2003. (U.S. Department of Agriculture 2005)
Please see our:
American Bird Conservancy. 2006a. Seabirds and Longlines. ABC Programs, Birds and Public Policy. (http://www.abcbirds.org/policy/seabirds.htm) (accessed 4/4/06)
American Bird Conservancy. 2006b. American Birds: an Endangered Species Act Success Story. (http://www.abcbirds.org/esa/AmBirdConservancy_ESAreport.pdf) (accessed 4/4/06)
Dahl, Thomas E. 1990. Wetlands losses in the United States 1780's to 1980's. U.S. Department of the Interior, Fish and Wildlife Service, Washington, D.C. Jamestown, ND: Northern Prairie Wildlife Research Center Home Page. (http://www.npwrc.usgs.gov/resource/othrdata/wetloss/wetloss.htm) (Version 16JUL97) (accessed 4/4/06)
Dahl, TE. 2000. Status and Trends of Wetlands in the conterminus United States 1986 to 1997. U.S. Department of Interior, Fish and Wildlife Service, Washington D.C. 82 pp. () (accessed 4/4/06)
Eisler, R. 1988. Lead hazards to fish, wildlife, and invertebrates: a synoptic Review. Contaminant Hazard Reviews. U.S Fish and Wildlife Service, Biological Report 85(1.14).
Goodbody, J. 2005. Green Acres. Audubon Magazine, Nov-Dec (pp 50-58).
Hughes, L. 2000. Biological consequences of global warming: is the signal already apparent? Trends Ecology Evolution 15: 56-61.
Oedekoven, CS, DG Ainley, and LB Spear. 2001. Variable responses of seabirds to change in marine climate: California Current, 1985-1994. Marine Ecology – Progress series 212: 265-281.
National Audubon Society. 2002. Black-footed Albatross. Bird Conservation, Audubon Watchlist, View Watchlist. (http://audubon2.org/webapp/watchlist/viewSpecies.jsp?id=32) (accessed 4/4/06)
Sanborn, W. 2002. Lead poisoning of North American Wildlife from Lead Shot and Lead Fishing Tackle. Hawkwatch International Publications. (accessed 4/4/06)
Spear, LB, and DG Ainley. 1999. Migration routes of Sooty Shearwaters in the Pacific Ocean. Condor 101: 205-218.
Thomas, CD, and JJ Lennon. 1999. Birds extend their ranges northwards. Nature 399: 213.
U.S. Department of Agriculture. 2005. Natural Resources Conservation Service, News release: NRCS data show significant gains in agricultural wetland acreage. http://www.nrcs.usda.gov/news/releases/2005/wetlandsgain.html. (accessed 3/24/06)
U.S. Environmental Protection Agency (EPA). 1999. Climate Change and Birds. Change on the Wing. Office of Policy: EPA-236-f-99-003. (accessed 4/4/06)
U.S. Environmental Protection Agency. 1994. Lead Fishing Sinkers: Response to Citizens’ Petition and Proposed Ban, Proposed Rule. Federal Register 59-11122-11143.
U.S. Fish and Wildlife Service. 2005. The Federal Duck Stamp Program. Protecting habitat: your Duck Stamp dollars at work. http://www.fws.gov/duckstamps/Conservation/conservation.htm. (accessed 3/24/06)
Walther, G-R, E Post, P Covey, et al. 2002. Ecological responses to recent climate change. Nature 416: 389-395.
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