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GLARO Research: Current Studies

Ongoing research projects in DU's Great Lakes/Atlantic Region
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Please click on one of the studies below to get more information and see photos associated with GLARO's ongoing and completed research studies:


Black duck henBlack Duck Study

For detailed information on the Black Duck Study in New Jersey, Virginia and Ohio, please visit the Black Duck Study homepage.




Spring Migration Study

Checking the traps

During spring migration, waterfowl depend on encountering suitable stopover wetland habitats to act as rest areas and to fuel the energetic demands of long-distance flight and subsequent breeding efforts. The loss and deterioration of wetland habitat along migration routes could create "bottlenecks" that ultimately limit waterfowl populations. The Great Lakes region has sustained tremendous wetland loss (Illinois: 85 percent, Indiana: 87 percent, Michigan: 50 percent, Ohio: 90 percent and Wisconsin: 46 percent) and degradation as a result of anthropogenic land-use conversion. As a result, this area may be an energetic bottleneck for waterfowl during spring migration, resulting in reduced body condition, survival and breeding effort.

In 2006, Ducks Unlimited and its partners initiated a multi-year study designed to determine the amount and types of wetland habitat required to support the nutritional requirements of spring-migrating waterfowl in the Great Lakes region. The results of this work will be used to help refine and guide conservation activities to meet the needs of spring-migrating waterfowl.

Six study sites were selected to represent longitudinal and latitudinal gradients and the variety of wetland habitats available to spring migrating waterfowl. Wetlands were sampled three times during spring to document food (plant and invertebrate) availability and distribution by habitat type. Surveys and time-activity budgets were conducted to document waterfowl habitat use, migration chronology and behavior. A sample of birds also was collected throughout the migration period to determine food habits in relation to available foods.

Searching for birds

Information from this research will be utilized to model the landscape with respect to waterfowl energetic carrying capacity. A hotspot map will be produced to guide conservation activities throughout the Great Lakes region. Publications, conclusions and conservation guidance as a result of this research are anticipated in 2009. For resources related to this and other GLARO studies, please see our Resource Library.

SamplingResearchers on the lookout

Habitat use

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Great Lakes Mallard Study

Mallard hen and brood

Mallards produced in the Great Lakes are extremely important to local and regional waterfowl harvest. In the Great Lakes and southeastern United States, the majority of mallards harvested are derived from the Great Lakes population. Spring waterfowl surveys in Michigan and Wisconsin suggest mallard breeding populations increased through the early 1990s but have since declined. This trend has raised concerns regarding potential factors limiting the population.

Prepping a mallard hen for implantation

In 2001, Ducks Unlimited and its partners initiated a three-year study to examine mallard reproductive ecology in the Great Lakes states. The goals of the study were to document reproductive parameters and identify which parameters most influence population growth via demographic modeling. The results of this work were used to help refine and guide conservation activities to meet the needs of breeding mallards in the Great Lakes region. For resources related to this and other GLARO studies, please see our Resource Library.

Mallards are paired

Nine study sites were selected that included a variety of landscapes representative of the region. At each site, 60 female mallards were decoy trapped and surgically implanted with radio transmitters. Females were then monitored daily throughout the breeding season to estimate breeding incidence, clutch size, hatch success and nesting effort, as well as the survival of adult females, nests and ducklings. A demographic model utilizing these estimates was then developed and used to conduct sensitivity analyses to identify which parameters most influence population growth.

Results suggested that population growth was most sensitive to changes in non-breeding survival, duckling survival and nest success. Overall, breeding season parameters accounted for the majority of the variation in population growth. Duckling survival was the breeding season parameter that was most influential. In addition, duckling survival was positively related to the amount of vegetated wetland and negatively related to the proportion of forest cover within brood-rearing areas.

Mallard nest with clutch


As a result of this information, Ducks Unlimited conservation programs were adapted to focus on restoring and protecting wetlands with mosaics of emergent vegetation and open water in sparsely forested areas. Conservation efforts targeting duckling survival also may lead to improved breeding incidence, nesting effort, pair densities and female breeding survival.



Map of study data

Mallard hen to be implanted

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