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.