By Douglas Hunter

As the Deepwater Horizon oil rig disaster in the Gulf of Mexico continued to unfold throughout the summer, Canadian scientists began considering the consequences of this unprecedented environmental disaster on the bird species that depend on the gulf region as a major winter stopover and migratory pathway.

Joe Nocera, a research scientist with Ontario’s Ministry of Natural Resources and an adjunct professor in the environmental and life sciences graduate program at Trent University, watched the impact of the spill on avian wildlife with concern. Nocera’s specialty is species at risk, and he has paid particular attention in his fieldwork to the white pelican, officially listed as threatened in Ontario. Like their cousins the brown pelicans, white pelicans are in the front ranks of migratory waterbirds under dire threat from the oil leak. The list of waterbirds – in addition to songbirds, on which the potential impacts are more difficult to gauge – in harm’s way is extensive.

“I would say it’s the fish-eating birds that will experience the earliest impact,” Nocera says. “[the oil spill] will affect any waterbird species that are in the gulf as more than a migratory path. The ones that stop over and eat fish are directly in contact with the oil.” Terns, cormorants and sea ducks are the Ontario birds most likely to suffer. Sea ducks alone include a range of species, among them mergansers, eiders, buffleheads and goldeneyes. As for white pelicans, he says, “we know very little about their wintering habits. It’s fair to say some of them do winter over there.”

Birds that use the watershed or wetlands of the gulf coast region also could suffer, depending how much damage the oil leak ultimately inflicts, directly and indirectly, on those areas. “It could range to even freshwater waterfowl using coastal areas temporarily. A lot of freshwater herons would be the most noticeably affected. Not all of them winter down that far, but some do.”

The scale of the potential impact of the oil spill is unknown, but seeing how many birds return in the spring of 2011 will provide insight into its effect on a number of species. The impact, however, could play out for years. “We learned some lessons from Exxon Valdez,” Nocera says, referring to the oil tanker spill 20 years ago in Alaska’s Prince William Sound. “But this is far worse. Hydrocarbon poisoning could shut down the reproductive ability of birds. We just don’t know at this point.”

“And if the oil enters the Gulf Stream and reaches Cape Cod,” Nocera adds, “the number of affected species will grow.”