by Jeff Wells
Oil from the Deepwater Horizon spill along Louisiana's Gulf Coast. Photo by Ducks Unlimited.
While the Gulf oil spill certainly has far-reaching consequences for people, the environment and industry, from a purely bird-centric view, the spill occurred in one of the worst possible places. The Gulf Coast serves as important habitat for hundreds of bird species, which use the region for breeding, wintering and stopover habitat. These birds, and the generations that come after them, are put at risk by the spill's potential impact on marsh and beach habitat.
The migratory birds of Canada's Boreal Forest make up a significant percentage of the migrating birds that winter in the Gulf Coast region or stop over during their travels farther south.
Canada's Boreal is home to more than 300 bird species, including 80 percent of North American waterfowl species, 63 percent of finches and 53 percent of warblers. Nearly 5 billion of Canada's migratory birds fly south in the fall, with many wintering or stopping in the U.S. Gulf region.
The Gulf Coast, especially the Mississippi River Delta, is vitally important for many wetland bird species. The marshes, beaches and tidal flats provide ideal nesting and migratory stopover habitat for millions of waterfowl, seabirds, shorebirds and other waterbirds. These habitats also house the fish, mollusks and other marine life of the Gulf of Mexico, which make up the food supply for these birds. Scientists worry that the impact on some of the smaller food sources like plankton could have a far-reaching ripple effect on the entire food chain.
As summer progresses into fall, the birds that winter or use the Gulf region to feed and rest during migration may be impacted by the oil spill. Beginning in early July and continuing into fall, many species of shorebirds that live and breed in Canada's Boreal and the Arctic migrate south.
By October, large numbers of ducks typically arrive in Louisiana marshes and spend the winter in areas rich with food. This includes species like the green-winged teal, American wigeon, ring-necked duck, and lesser and greater scaup, all of which have more than half of their breeding populations within Canada's Boreal. Most of these species are particularly reliant on the Louisiana coast. An estimated 40 percent of the green-winged teal, 30 percent of scaup and 20 percent of American wigeon and ring-necked ducks that depart the Boreal winter on the Louisiana coast.
Oil spill impacts infographic – click to enlarge.
When the oil spill first occurred, many experts rightfully feared this spill would have a detrimental impact on a variety of birds. Currently, nesting birds are bearing the heaviest burden. This includes beach- and barrier-island-nesting plovers, terns, gulls, herons, egrets and pelicans. Louisiana's coast is estimated to support 77 percent of the U.S. breeding population of sandwich tern, 52 percent of forster's tern and 44 percent of black skimmer. Sadly, many of North America's most at-risk species also spend some portion of the year in the region, including yellow rail, black rail, snowy plover, piping plover and short-billed dowitcher. Clearly, the oil spill has potential to impact these species, and for some, could have long-term implications for the health of their overall populations.
As fall migration begins, we may see additional impacts to birds as they return to wintering grounds along the Gulf. Adding to the toll of birds lost from direct contact with oil are the longer-term effects stemming from physiological impacts of ingested oil that may lower breeding success rates.
These factors pose the largest threat to the birds that either migrate through or spend their winters in the region. While the majority of attention to date has been given to local resident species, there is a chance for lingering impacts for many of the waterfowl and shorebirds that breed in Canada's Boreal Forest and the Prairie Pothole Region and migrate to or winter in the Gulf region. This includes mallards, northern pintail, green-winged teal, American wigeon, ring-necked duck and greater and lesser scaup.
Many migratory, wetland-dependent smaller birds and shorebirds, including black-bellied plover, semipalmated plover, greater and lesser yellowlegs, solitary sandpiper, least sandpiper, dunlin, stilt sandpiper, short-billed dowitcher, wilson's snipe and many others, will stop in the region to rest and feed before continuing on their journeys to the Caribbean and South America. They may encounter habitats and food sources contaminated with oil on their journey south that could cause mortality.
While there is likely little we can do to mitigate the effects of the oil spill on Canada's migratory birds, there is hope for many of these species. We have the opportunity to preserve critical summer habitat for billions of birds in Canada's Boreal Forest. By maintaining this largely intact forest ecosystem—4.4 million square kilometers of intact forest—we will save the "the other duck factory," also known as the "Bird Nursery of the North." This forest is home to more than 300 breeding bird species and provides habitat for nearly 5 billion migratory birds that fly south from the Boreal each fall.
Boreal Forest habitat. Photo by Ducks Unlimited Canada.
Though Canada's Boreal is largely intact, industrial disturbance has led to habitat loss and fragmentation that affects bird populations. More than 30 percent of Boreal forest land has been allocated to logging, mining and other energy development, and only 12 percent of the forest has been permanently protected. Habitat loss and fragmentation is one of the leading causes of declining bird populations worldwide. By protecting the 1.3 billion acres of Canada's Boreal forest—one of the largest intact forest ecosystems remaining on Earth—we can give these critical populations of migratory birds a fighting chance of recovering from devastating occurrences such as the Gulf oil spill.
Dr. Jeff Wells is the senior scientist for the Boreal Songbird Initiative, an organization dedicated to outreach and education about the importance of the Boreal Forest region to North America's birds, other wildlife and the global environment. He is the author of Birder's Conservation Handbook.
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