A Wing and a Scare

After Katrina, a rough winter lies in store for Minnesota's migratory birds

In the weeks since Katrina and Rita devastated the Gulf Coast, there has been no shortage of stories on the myriad miseries they wrought. Most coverage has focused on the human carnage or the economic toll. And, in a nation where a lot of people feel more connected to their pets than their neighbors, there has also been an abundance of ink spilled on the suffering of all the dogs and cats left marooned.

But despite the wall-to-wall coverage, some questions remain largely unexamined. For instance: What will Katrina's effects be on Minnesota wildlife? At first blush, the matter may seem picayune. But among bird lovers, hunters, and natural resource managers, there is growing concern that the havoc wreaked by the storms could spell trouble for some of the many Minnesota bird species that winter in Louisiana.

Take the case of the lesser scaup, known more commonly in the Midwest as the bluebill. For generations, the graceful, fast-flying birds have been a favorite target of Minnesota duck hunters. But in recent years, bluebills have suffered a worrisome and largely unexplained decline in population, as have many other Minnesota duck species. In the last year alone, according to DNR counts, the number of breeding ducks in Minnesota declined by about 30 percent.

The bluebills' troubles may well worsen in the coming months. Many of the birds spend their winters at Lake Pontchartrain, where they feed on clams and other bivalves. Such organisms tend to accumulate toxins, which means the bluebills might be poisoned if they feed in the now badly degraded Pontchartrain. According to some estimates, the Katrina oil spill is roughly two-thirds the size of the spill from the Exxon Valdez, a disaster whose environmental repercussions lingered for more than 15 years after the event. To make matters worse, many experts think it will be more difficult to clean the fouled marshlands and bayous of Louisiana than the rocky, relatively well-defined shorelines of Alaska.

"Ducks are used to changes in their environment. But I don't know if they've seen anything quite like Katrina," says Steve Cordts, a waterfowl specialist with the Minnesota Department of Natural Resources. "So it's hard to say what impacts it will have on fitness of birds or overall survival. I don't think the information exists on the extent of the damage." Right now, he notes, wildlife managers are scrambling for money to monitor the water quality and ready themselves for the winter bird counts.

Aside from the issue of pollution, scientists are worried about large-scale loss of coastal habitat. Not only did the storm surge simply wipe out a lot of coastal marshes--which were disappearing at the rate of 25 square miles per year before Katrina--it also forced highly saline ocean water into freshwater marshes. Consequently a lot of freshwater plant species are likely to die off, resulting in significant changes to the habitat. That's significant because freshwater marshes tend to have much more varied plant communities than saltwater marshes and hence promote greater diversity in animal life.

"Everyone says it's nature, it's a natural occurrence, it will come back. And that's true. But it might take an incredibly long time," notes Tom MacKenzie, an employee with the U.S. Fish and Wildlife Service who spent the past month touring and photographing wildlife areas damaged by the storms. "On the positive side, we're hoping this provides increased attention to protecting our coasts. Why don't we come up with a buffer zone that has swamps and bayous? The more wetlands you've got, the more hurricane protection you've got."

Carrol Henderson, a nongame wildlife specialist with the Minnesota DNR, says he is uncertain how Katrina will affect other migratory species from Minnesota. "This is a real interesting and challenging question. When you look at aerial photos of former shallow marshland on the coast, it appears that lots of those areas are gone," Henderson notes. For birds that rely on wet, swampy soil and shallow water habitat--including common Minnesota nesters like herons, egrets, wood ducks, pied-billed grebes, and woodcocks, as well as relatively rare species such as the American bittern--the loss of such shallows will leave the birds with two options: starve or move. Meanwhile, many tree-nesting species familiar to Minnesota birders--warblers and other songbirds--will find the hurricane-ravaged forests of Louisiana suddenly much less suited to their needs.

Tom Moorman, a director of conservation planning with the group Ducks Unlimited, figures most migratory birds will simply fly on if they discover their wintering grounds degraded. But there could be some exceptions, especially for philopatric birds--the species that habitually return to the same summering and wintering grounds. Some of the philopatric species affected by Katrina (such as Canada geese and canvasback ducks) have relatively robust populations. Fortunately, Moorman notes, the hurricanes narrowly missed the wintering grounds of much more vulnerable philopatric species, such as the whooping crane.

In the end, Moorman is relatively optimistic about the overall chances for waterfowl, especially the Minnesota migrants. "Most birds are pretty good at finding new areas, so I would not anticipate survival rates that will be dramatically lower," he says. "It's probably not something that you will notice on a continental scale. There will be a significant reduction in the number of birds that winter in coastal Louisiana." And, he notes, waterfowl migrating to Louisiana will have one advantage this fall: While the Fish and Wildlife Service has chosen not to reduce bag limits in response to the storm, there will probably be a lot fewer hunters in the swamps and bayous.

 
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