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Scientists estimate seed abundances to calculate seasonal carrying capacities and assess wetland management actions for waterfowl and other wildlife using soil core samples. We evaluated recovery of known quantities of moist-soil seeds from whole and subsampled experimental core samples containing 12 seed taxa representing small, medium, and large size classes. We recovered 86.3% (SE = 1.8) of all seeds added to experimental cores; 8.3% (SE = 1.2) of seeds were destroyed during the sieving process and 5.4% (SE = 1.2) were not recovered by observers. Recovery rates varied by seed size, but not seed quantity or disproportionate ratios of seed-size classes. Overall seed recovery rates were similar between subsampled ( = 81.2%, SE = 3.6) and whole—processed core samples ( = 86.3%, SE = 1.8). We used recovery rates to generate size-specific, taxon-specific, and constant correction factors and applied each to actual core sample data. Size-specific correction factors increased seed mass estimates in the...

Agricultural fields are often overlooked as post-breeding and migratory bird habitat, even though many species use row-crop fields in the northern Great Plains. We monitored bird use, crop and non-crop vegetation characteristics and abundance, and land use around (≤2.4 km) 35 8-ha Wildlife Conservation Sunflower Plots (WCSP) and one commercial sunflower and non-sunflower row-crop field, paired with each WCSP, in fall 2004 and 2005. We excluded four species of blackbirds from our analysis that commonly form large foraging flocks and ubiquitously use agricultural fields. A diverse community of migratory birds used WCSP and commercial sunflower compared to other non-sunflower crops in North Dakota. Both WCSP (mean = 24.4 birds/ha, se = 2.7) and commercial sunflower (mean = 12.7 birds/ha, se = 1.7) harbored greater densities of birds (P < 0.01) than did other non-sunflower row crops (mean = 7.2 birds/ha, se = 1.1). Migratory birds were more strongly associated with vegetation within field...

In 2004, USDA’s Wildlife Services began to cost share 8-ha Wildlife Conservation Sunflower Plots (WCSP) with sunflower growers to lure migrating blackbirds away from commercial sunflower fields. During late summer and fall of 2004 and 2005, blackbirds used sunflower more than other crops, especially WCSP placed near blackbird roosts. Blackbird density in WCSP and commercial sunflower was negatively associated with nearby habitat types ( 10 km from WCSP. Across both years, birds removed an average of 435 kg/ha and 49 kg/ha of sunflower seed in WCSP and commercial sunflower fields, respectively. Additionally, in 2005, blackbirds removed 181 kg/ha of seed in commercial sunflower >10 km from WCSP (reference fields). WCSP had a costbenefit ratio of 3.4:1; however, in reference sunflower fields, birds removed 3.2 times more sunflower seed than in commercial sunflower fields near WCSP. Our data suggest that producers should consider planting cost-shared WCSP as part of an integrated pest management strategy to reduce blackbird damage to commercial sunflower.

Energetic carrying capacity of habitats for wildlife is a fundamental concept used to better understand population ecology and prioritize conservation efforts. However, carrying capacity can be difficult to estimate accurately and simplified models often depend on many assumptions and few estimated parameters. We demonstrate the complex nature of parameterizing energetic carrying capacity models and use an experimental approach to describe a necessary parameter, a foraging threshold (i.e., density of food at which animals no longer can efficiently forage and acquire energy), for a guild of migratory birds. We created foraging patches with different fixed prey densities and monitored the numerical and behavioral responses of waterfowl (Anatidae) and depletion of foods during winter. Dabbling ducks (Anatini) fed extensively in plots and all initial densities of supplemented seed were rapidly reduced to 10 kg/ha and other natural seeds and tubers combined to 170 kg/ha, despite different starting densities. However, ducks did not abandon or stop foraging in wetlands when seed reduction ceased approximately two weeks into the winter-long experiment nor did they consistently distribute according to ideal-free predictions during this period. Dabbling duck use of experimental plots was not related to initial seed density, and residual seed and tuber densities varied among plant taxa and wetlands but not plots. Herein, we reached several conclusions: 1) foraging effort and numerical responses of dabbling ducks in winter were likely influenced by factors other than total food densities (e.g., predation risk, opportunity costs, forager condition), 2) foraging thresholds may vary among foraging locations, and 3) the numerical response of dabbling ducks may be an inconsistent predictor of habitat quality relative to seed and tuber density. We describe implications on habitat conservation objectives of using different foraging thresholds in energetic carrying capacity models and suggest scientists reevaluate assumptions of these models used to guide habitat conservation.

Major floods elicit calls for more comprehensive and multi-faceted approaches to flood management. In the future, adding floodways and flood storage areas to traditional structural strategies (e.g. dams and levees) may be a viable strategy. Beyond reducing flood damages, there is growing societal interest in floodplain services, including nutrient processing and supporting fisheries and wildlife habitat. In April 2013, a record flood on the Illinois River created a natural floodplain management experiment within two restored, but disconnected floodplains. With the benefit of extensive pre-flood data at both sites, we evaluated the biological response to a minor (levee overtopping) and a major (levee failure) flooding event. Our intent was to test the ecological resilience of restored floodplains to these two alternative management scenarios. We hypothesized that a minor flood event would have little effect on ecosystem structure, whereas the major flood event would result in lower production and diversity of zooplankton; increase invasive vegetation and decrease desirable submerged and emergent aquatic vegetation; and decrease overall waterbird use. Case studies such as this are critically needed to inform policy-makers and managers of the trade-offs between alternative floodplain connectivity regimes on ecological services.

Wetlands are highly productive ecosystems that provide habitat for a diversity of wildlife species and afford various ecosystem services. Managing wetlands effectively requires an understanding of basic ecosystem processes, animal and plant life history strategies, and principles of wildlife management. Management techniques that are used differ depending on target species, coastal versus interior wetlands, and available infrastructure, resources, and management objectives. Ideally, wetlands are managed as a complex, with many successional stages and hydroperiods represented in close proximity. Managing wetland wildlife typically involves manipulating water levels and vegetation in the wetland, and providing an upland buffer. Commonly, levees and water control structures are used to manipulate wetland hydrology in combination with other management techniques (e.g., disking, burning, herbicide application) to create desired plant and wildlife responses. In the United States, several conservation programs are available to assist landowners in developing wetland management infrastructure on their property. Managing wetlands to increase habitat quality for wildlife is critical, considering this ecosystem is one of the most imperiled in the world.

The Illinois River historically provided high-quality habitat for a variety of migratory birds but sedimentation, management for commercial navigation, and increasing hydrologic variability have contributed to reductions in aquatic vegetation and naturally occurring foods for waterfowl. Cover of aquatic vegetation within the Illinois River Valley (IRV) declined during the 1950s, and it has not recovered in its historical range. The Dresden and Starved Rock reaches of the Illinois River, unlike other reaches in the IRV, still retain aquatic macrophytes in the main channel and connected backwater wetlands. To determine energetic carrying capacity of seeds and tubers for waterfowl in the upper Illinois River, we collected benthic core samples from random locations throughout the Dresden and Starved Rock reaches in falls 2013–2014. All sampling locations (i.e., main channel and connected backwater wetlands) had low mean density of seeds and tubers (