Why are northern pintails declining while most duck species recover?
- T. Edward Nickens
- Apr 01, 2004
IT LOOKS SO GOOD TO A DUCK. From 200 feet above the rolling sweep of southern Saskatchewan, the land appears as inviting as it has for millennia—a tawny sea of short grasses bejeweled with shallow pond after shallow pond for as far as the eye can see. So the bird cups her wings and calls it home: a little corner of prairie country. A fine place to raise a brood of northern pintail ducks.
The problem is that it looks pretty good to a farmer, too. That sea of short grasses turns out to be a few hundred acres of wheat stubble, and a month after the duck settles in, a large tractor sends the panicked pintail hen into the sky. Her unhatched eggs lie defenseless on the ground.
It’s a scene that is repeated countless times, in countless spring fields, across the great swath of prairie that blankets much of Montana, North and South Dakota and the Canadian provinces of Alberta, Saskatchewan and Manitoba. And the pintail hens’ predicament seems to be taking a tremendous toll on the species. In the spring of 2002, North American pintail numbers hit an all-time low of 1.79 million birds, 39 percent below their long-term average and just a fifth of the duck’s population peak of more than 10 million birds in 1956.
The pintail’s plight stands in stark contrast to the status of most North American duck species, which have responded well to improved water conditions and crop policies instituted in the 1990s across much of the famed “duck factory” of the prairie pothole region. (See below.) Obvious problems facing pintails are negative effects of farming and predation on nesting success in the ducks’ northern breeding grounds. But these alone do not fully account for the species’ dramatic population drops. Indeed, why “sprigs,” as some old-timers call the long-tailed ducks, have not fared better over the past decade is one of the great conundrums of waterfowl science today.
To try and solve the mystery, researchers on both sides of the U.S.-Canadian border have turned to groundbreaking, high-technology research and enormous landscape-scale studies. The scientists have two major goals: to identify the pintail’s most important spring migration stopovers and to better understand its reproductive ecology. Already, the research is providing new clues to the unusual habits and habitats of the prairie’s most regal duck. And it is underscoring just how large the challenges to pintail conservation remain.
On the wing, pintails are so unlike other waterfowl that identifying them is a snap. They’re known as “the greyhound of ducks”: slender birds with a swift wingbeat and overlong necks and pointed tails that set them apart from other species even from a distance.
Pintails are unlike most dabbling ducks in a number of other ways, too, many of which play a role in hampering their recovery. Unlike marsh and tallgrass-nesting ducks such as mallards, gadwall and blue-winged teal, pintail hens seek out short-grass prairie and farm fields cloaked in sparse stubble. They nest earlier and lay fewer eggs than other similarly sized ducks. Sprigs also are among the first duck species to leave wintering grounds in the early spring, which puts them at risk of running into difficult weather, and they choose shallow water bodies over deeper ponds, an unfortunate preference during dry conditions. Observes Karla Guyn, a waterfowl biologist with Ducks Unlimited Canada: “Pintails play with a bad hand of cards all year long, especially given the way humans have changed the landscape.”
Beyond such generalities, scientists don’t know a lot about pintails, especially about their life on the move. “The biggest hole has been knowledge about spring migration,” explains Michael Miller, a waterfowl biologist with the U.S. Geological Survey’s (USGS) Western Ecological Research Center. To fill the gaps, USGS biologists launched a four-year satellite telemetry study in the spring of 2000 to pin down migration routes and tease out possible connections between wintering, migrating and nesting habitats.
Dubbed “Discovery for Recovery,” the international project first put a microscope on the spring migratory patterns of North America’s largest wintering population of pintails—the approximately one million birds that spend the cold months in California’s Central Valley. In 2002, the project was expanded to pintails wintering in south-central New Mexico, along the Texas Gulf Coast and in the Texas playa lakes region. Wearing tiny, 20-gram transmitters affixed to their backs with Teflon ribbon, pintails provide location signals for five hours every third day of the migration. Picked up by orbiting satellites, the data are sent to researchers via e-mail.
The work in California, Miller reports, has accomplished more in just a few years than many years of traditional leg banding could have. Specifically, his team has discovered the exact spring migration paths used by this critical western population and identified its most important staging areas. Pintails, it turns out, use as many as five different routes as they depart the Central Valley and fly to their breeding grounds.
One critical piece of new information comes from the 10,000-square-mile Klamath Basin on the Oregon-California border. A large majority of California’s wintering pintails spend nearly two months here in what conservationists call the western Everglades, laying on fat reserves desperately needed for a continued northward push. But this region is now embroiled in a bitter fight over water resources and land use. Approximately 80 percent of the upper basin lands are farmed and heavily irrigated today, leaving fish including the endangered Klamath River coho salmon on the ropes. “Under the Endangered Species Act, those fish get more water,” says Miller, “and that leaves farmers and ducks standing in line. It’s a very difficult situation for everyone—including pintails.”
Another discovery with huge conservation consequences is the fragile public safety net afforded Pacific Flyway pintails. In a typical year, between 50 and 80 percent of the land used by migrating pintails is in private hands. Among the most important layovers are several river valleys in western Montana and the Chewaucan Marsh of southern Oregon. “Identifying these privately owned stopover areas should really focus land protection and management efforts,” Miller says.
This year, as these major satellite studies wind down, another massive project based on birds outfitted with conventional radio transmitters is going strong. For the past two years, researchers in Texas and Nebraska have been monitoring hundreds of radio-tagged pintails as they migrate from the Gulf Coast and the plains to the rainwater basins of Nebraska. Following the birds in trucks and airplanes, the scientists are learning how pintails use different kinds of migratory habitat.
“We believe conditions on the wintering grounds and through the spring migrations impact reproduction and survival on the breeding grounds,” says U.S. Fish and Wildlife Service biologist and project participant David Haukos. “We have to make sure that the birds on the playas have the fat reserves needed to get to Nebraska’s rainwater basins. And from there, they need enough fuel to get them to the Canadian prairies in good condition.”
The project is intensive—Haukos and his colleagues locate each bird at least once a week—but the labor has a huge payoff: Scientists are able to follow individual female pintails for up to 200 days. “This will open a new window on the life history of individual birds,” says Haukos. “Once we mark a bird we’ll know how much she weighs in the fall, whether she prefers to feed in certain fields or certain types of wetlands, and how she responds to disturbance.”
These details may finally give scientists and land managers concrete strategies to stem the pintail’s decline. In the Texas playa country, for example, pintails and other waterfowl depend on private land, unlike California, which boasts large areas of public land. Until now a lack of specifics has hampered on-the-ground protection in Texas. The new studies will suggest how many playas pintails need in a given area, how far apart they should be, and what kinds and how much food are required.
While U.S. scientists fill in these blanks of pintail migration, waterfowl conservationists in Canada are coming to a consensus about what needs to be done to improve nesting success on the bird’s breeding grounds. The obstacles here have more to do with human society than with waterfowl biology. From the 1950s through the 1970s, many Canadian farmers allowed a portion of their acreage to lie idle during the early part of the growing season, a practice called summerfallow. The resulting stubble fields were a magnet—and safe haven—for short-grass-loving pintails. But modern farmers, pushed to turn a profit on every possible acre, have increasingly abandoned the practice.
At the same time, greater reliance on spring-seeded crops such as barley, spring wheat and canola, coupled with larger mechanized equipment, has swept across the prairies like a wild wind. The result: the most dramatic ecological shift to occur here in the past quarter century. Between 1981 and 1996, more than 8 million acres of Canadian prairie summerfallow—a landmass nearly four times the size of Yellowstone National Park—became subject to spring seeding. It’s been a catastrophe for pintails: In one study, the duck’s nesting success in spring-seeded lands averaged just one successful nest per 1,000 acres, compared to one per 80 acres in fall-seeded crops.
Boosting pintail populations, then, will mean changing the world in which they live—or more specifically, the place in which they raise their young. To help start the process, Ducks Unlimited Canada has launched its first-ever species-specific conservation strategy. Part of the effort, called “Restoring the Tradition,” will encourage legislative support for incentives that recognize ecological benefits of taking marginal cropland out of production. Another priority is to support breeding and development of new weather-resistant strains of winter wheat. But the strategy’s primary focus is to convince first a few, and ultimately thousands, of farmers to convert part of their fields to fall-seeded crops such as winter wheat and fall rye. “We’ve learned that to change duck populations you have to change big, big landscapes,” says Guyn. “And that’s a big, big challenge.”
But no bigger, perhaps, than the challenge that confronts a pintail hen come April. Equipped with a homing instinct, a breeding urge and wings that can carry her 1,000 miles in a single day, she needs two more things that only humans can provide today: Healthy habitat as she heads north. And a safe home for the next generation of sprigs.
According to North Carolina writer T. Edward Nickens, there is nothing quite as gallant as a pintail drake with wings set over a winter marsh.
The Lesser Scaup: Another Unlucky Duck
I have watched lesser scaup whirl in winged tornadoes above North Carolina’s Pamlico Sound, hundreds of ducks in a single flock, and flock after flock lined up on the horizon. And I’ve watched scaup numbers plummet as quickly as the birds drop into decoys with a famous lack of caution. Like the northern pintail, the lesser scaup is faring poorly in an era of rebounding duck populations. Today scaup numbers are 29 percent below their 1955-2003 average. “Exactly why lesser scaup continue to decline is unknown, but it is no doubt a combination of factors,” says NWF senior scientist Doug Inkley.
Biologists are studying a number of potential causes. Lesser scaup breed extensively in the northern boreal forests of Canada, where timber and mining activities have ramped up over the years. Global climate change may also be playing a hand; warming conditions on the breeding grounds could be causing heavy flooding along rivers where scaup nest. Over the past 20 years, the duck’s boreal forest population, which includes nearly 70 percent of all lesser scaup, has been declining at 150,000 birds per year.
Problems during migration may also be playing a role. Like pintails, scaup need healthy habitats along migratory paths to arrive on the breeding grounds in peak condition. But certain kinds of freshwater shrimp, a primary food, have nearly disappeared from many scaup waters. In addition, introduced zebra mussels in the Great Lakes are known to harbor high levels of selenium. It could be that scaup, which eat the mussels, are suffering from contamination, too.
“For years it was hard to get people excited about this little duck,” says Alan Afton, a wildlife biologist at Louisiana State University who has studied lesser scaup for four decades. “That’s finally beginning to change, but there are a lot of frustrating questions.”—T. Edward Nickens
North American Duck Revival
By the mid-1980s, populations of most of North America’s waterfowl species had declined to record lows, devastated by habitat destruction and particularly by the draining of wetlands for agriculture. In response, the governments of the United States and Canada teamed up in 1986 (joined by Mexico in 1994) to launch the North American Waterfowl Management Plan, an ambitious international conservation project to restore the continent’s duck, goose and swan populations. Passed in 1989, the North American Wetlands Conservation Act embraced the plan by providing federal funding for wetlands conservation in the United States, Mexico and Canada when matched by state and private dollars. To date, federal, state and private partners have worked to protect, enhance or restore more than 8 million acres of wetlands habitat. Their efforts are paying off: Today populations of most North American duck species are stable or rebounding.
Dabbling Versus Diving
Dabbling ducks like the northern pintail feed primarily by dipping their bills into the water or by tipping forward in shallow water to probe the bottom. These ducks rarely dive and take to the air directly without running. By contrast, the bufflehead is a diving duck. The feet of diving ducks are positioned further back, enabling the birds to dive underwater for food in deeper waters. Heavier ducks, they often run along the water’s surface before taking off and fly faster with quicker wingbeats. North America is home to 23 species of diving ducks and 16 species of dabbling ducks.