By David Howerter, Ph.D., and Johann Walker
The Prairie Pothole Region
(PPR) of the United States and Canada forms the heart of duck production in North America. DU scientists working in the PPR today benefit from research conducted by generations of scientists who came before us. Pioneering work conducted in the late 1930s and early 1940s by early waterfowl scientists Al Hochbaum and Lyle Sowls culminated in two seminal books, The Canvasback on a Prairie Marsh
and Prairie Ducks
, respectively, which provided some of the first insights into the ecological interplay between ducks and their environments. These volumes are must reads for aspiring waterfowl biologists
to this day. Later, luminaries such as Lew Cowardin, Ray Greenwood, and Al Sargeant of the Northern Prairie Wildlife Research Center in Jamestown, North Dakota, conducted studies that contributed immensely to our understanding of duck breeding ecology.
An important lesson from this early research was that ducks don't recognize the international border between Canada and the United States—the PPR is a single ecosystem. DU has long recognized this fact and works in both countries to solve the problems facing waterfowl. DU also conducts extensive research to help guide its prairie conservation programs. These studies focus on several issues that are of vital importance to accomplishing DU's conservation mission
Evaluating Landscape Change
At its core, DU is in the landscape-change business. We either attempt to change landscapes in a way that restores ecological functions that benefit waterfowl and their habitats
, or we attempt to prevent change that will harm these habitats and the birds. Understanding how landscape change affects duck populations is pivotal to the conservation work we do. That's why we continue to conduct these types of investigations.
In 2002, DU launched sister studies in the U.S. and Canadian PPR to evaluate the key tenet underlying many of our prairie conservation actions: that nesting success—the proportion of nests that hatch—is highest, on average, on landscapes that have abundant grassland habitat. These studies, which are scheduled to wind down in 2011, have examined duck nesting success on more than 180 study sites in Alberta, Saskatchewan, Manitoba, and North and South Dakota. In total, data have been collected on nearly 20,000 duck nests.
Such a large effort was necessary because the PPR is so dynamic. Periods of drought and abundant water, fluctuating predator populations, and changing land use all affect duck nesting success. Only with large samples of nests are we able to account for all these factors and achieve a statistically clear picture of the impact our work has on the birds we care so much about.
Under favorable conditions, more duck nests hatch in cropland-dominated landscapes than many researchers expected. (photo by Jason Riopel, DU)
So what have we learned? Preliminary results suggest that environmental conditions play an even larger role in determining duck nesting success in a given year than we previously thought. There is growing evidence that landscape-level wetland conditions have a larger impact on duck nesting success than many other variables. In other words, under favorable wetland conditions more duck nests hatch in cropland-dominated landscapes than many of us expected. These results don't mean that grassland habitat is any less important to breeding ducks. In fact, preliminary data from recent large-scale brood surveys conducted by DU and partners in North Dakota, South Dakota, Minnesota, Iowa, and Saskatchewan indicate that duck broods are most plentiful in late July on landscapes with extensive grassland and numerous small wetlands. But our findings do suggest that the relationships between ducks and their habitats are incredibly complex as prairie landscapes transition through their characteristic wet-dry cycles.
Measuring the Value of Waterfowl Habitat
Waterfowl habitats provide a wealth of benefits to society that, until recently, went largely unappreciated by the general public. In addition to providing important wildlife habitat, wetlands remove excess nutrients and pollutants from water that flows into lakes, rivers, and groundwater. Moreover, wetlands store water and reduce the impacts of flooding by regulating stream flows, and water stored in wetlands helps recharge aquifers.
Recent investigations by DU scientists have also demonstrated that wetlands sequester large amounts of carbon, thereby reducing amounts of greenhouse gases in the atmosphere. Quantifying these benefits provides society with a new appreciation for the services that waterfowl habitats provide, and hopefully will encourage decision makers at various levels of government to support policies to conserve them.
Putting Science into Practice
helps DU measure the effectiveness of the suite of conservation actions that we employ on the prairie landscape. Protection and restoration of wetland and grassland habitats important to ducks
are DU's highest priorities on both sides of the border. That's a huge job and requires a diverse mix of approaches guided by sound science
. We use direct programs like conservation easements or grassland and wetland restorations to conserve habitat incrementally. Policy efforts that can result in extensive, landscape-level impacts over a shorter time frame are also important. The Conservation Reserve Program (CRP)
in the United States is a prime example of a DU-supported government policy that has had a positive effect on waterfowl populations in the PPR. Scientific knowledge has helped DU and its partners repeatedly argue in favor of CRP extensions and reenrollments in the PPR. Extensive, long-term research into relationships between duck populations and their habitats provides the crucial information base needed to guide current and future conservation policies across the prairies and beyond.
Another important benefit of these studies is that they allow DU scientists to develop powerful computer-based tools to plan future conservation actions. These tools allow us to incorporate the best scientific information available to target landscapes and design a mix of conservation programs that will accomplish our objectives in the most cost-efficient manner. Planning tools developed to guide waterfowl conservation on the prairies have become a model for bird conservation throughout North America. These tools make it possible for conservation planners to visualize the extent of existing habitat, identify opportunities for habitat restoration, and prioritize alternative actions. To be most useful, these tools require constant adaptation as the threats to waterfowl populations and their habitats change over time. Waterfowl conservation strategies must also change in response through a continuous process of implementation, evaluation, and adaptation.
The greatest long-term threat to prairie duck populations has historically been conversion of grasslands and wetlands to agricultural production. Given growing demand for food and fuel, agricultural intensification remains a concern for prairie ducks, but a relatively new concern is widespread, intensive energy development driven by rising demand for oil and electricity. Wind farms have become increasingly common on the prairie landscape in recent years. And while wind energy is generally viewed as a “green” energy source, the effect of wind towers on grassland-nesting birds—including ducks—is uncertain.
To help answer these questions, DU and partners have initiated research to investigate whether wind farms affect settling of breeding ducks on nearby wetlands and whether direct mortality of ducks striking wind turbines is a concern. Analyses are ongoing, but preliminary results indicate that in the first three years of operation the impact of wind towers on breeding ducks is probably less negative than the impact of conversion of upland habitat to cropland. DU will continue to conduct research to learn more about the potential negative impacts energy development could have on prairie ducks and their habitats. The next step is to measure the cumulative effects across the PPR as more land is impacted by various forms of energy development in the future.
Training the Next Generation
Just as we have benefited from the knowledge of previous generations of scientists, we must ensure that a new generation of waterfowl scientists is trained to step in and help lead waterfowl conservation into the future. Accordingly, DU engages with many universities throughout North America and contributes to the graduate education of many students. Partnerships with universities not only ensure that bright young scientists receive the training they need, but also provide DU access to intellectual resources at universities to help answer questions important to our mission. DU Canada and DU Inc. jointly sponsor five fellowships each year to help support graduate student projects, and graduate students partner with DU scientists on most of our research projects.
Responding to Declining Populations
When populations of ducks and geese
fall persistently below historical levels, DU conducts research to indentify the causes of these declines and develops conservation strategies to reverse the trend. Continentally, northern pintail
and lesser scaup populations are both substantially below their long-term averages. Accordingly, DU has launched investigations into the potential causes driving declines of both species.
research has focused on boreal landscapes, where the decline of this species appears to have been most severe. In contrast, studies of pintails have focused on the prairies—especially in southern Canada—where these birds have suffered their greatest declines. Pintails, more than any other prairie-nesting ducks, are inclined to choose croplands as nesting habitat. Early analyses suggested that this penchant for nesting in cropland, combined with the modernization of agricultural machinery, which has allowed farmers to work fields earlier in the breeding season than in the past, has resulted in a high proportion of pintail nests being destroyed during normal farming activities.
Once a leading hypothesis for the cause of the pintail decline was identified, DU developed a strategy for the bird's recovery guided by the latest scientific research. Most of the pintail production on the prairies occurs on private lands, and cereal grain production is a primary source of income for many of the region's landowners. Consequently, DU sought a solution that would provide improved habitat for pintails while also allowing landowners to continue to make a living by farming the land.
Winter wheat potentially offers a partial solution. Planted in the fall, winter wheat is tilled less frequently in the spring, when ducks—especially pintails—are nesting. Harvest also occurs after most pintail nests have hatched, so including winter wheat in crop rotations in areas where pintails are abundant nesters provides a promising alternative to spring-seeded cereals. Unfortunately, at the outset, winter wheat in the PPR had some serious agronomic challenges. Early varieties were susceptible to both winter kill and disease. Farmers were understandably leery of including winter wheat as a primary component of their farming enterprises. Not to be deterred, DU partnered with
Dr. Brian Fowler, a prominent plant breeder at the University of Saskatchewan, to develop winter-hardy and disease-resistant strains of winter wheat that could thrive in the harsh prairie environment. Today, the number of winter wheat acres planted annually throughout the PPR is increasing, and most of the varieties being planted stem from Dr. Fowler's lab.
Importantly, early research indicates that ducks hatch approximately 12 times more nests per acre in winter wheat than they do in spring-seeded cereals planted nearby. Evaluations of winter wheat continue on both sides of the border as we fine-tune where this crop is likely to be most beneficial to nesting ducks. And in 2011 and 2012, DU scientists from the United States and Canada will be partnering to study duckling survival on study sites in Saskatchewan and North Dakota to ensure that more nests hatched in winter wheat also means more ducks in the sky.
Encouragingly, pintail numbers have been on the upswing in recent years. In 2010, an estimated 3.5 million breeding pintails were present in the traditional survey area—the largest population since 1997 and near a 30-year high. This allowed the U.S. Fish and Wildlife Service to liberalize the daily bag limit on pintails to two birds in every flyway.
Ducks Unlimited has always delivered conservation guided by the best available scientific information. By continuing to invest in science, DU is positioning itself to continually improve its conservation programs—evaluating the key assumptions underlying its conservation actions and adapting its programs with new information. The end result is increasing returns on DU's conservation investments and more ducks in North America's skies.
Dr. David Howerter is national manager of the Institute for Wetland and Waterfowl Research at DU Canada headquarters at Oak Hammock Marsh. Johann Walker is manager of conservation programs at DU's Great Plains office in Bismarck, North Dakota.