Mississippi Alluvial Valley Research Articles

Seasonal Resource Selection and Use of Hardwood Regeneration by Translocated Wild Turkeys in the Mississippi Alluvial Valley

Reforestation practices have intensified in the Mississippi Alluvial Valley (MAV) of the United States of America with the aid of Farm Bill programs during the past three decades. Increases in reforested land also enhance possibilities to restore once-abundant but currently sparse species, such as eastern wild turkeys (Meleagris gallopavo silvestris) in the MAV. However, it is unknown whether <20-year-old hardwood regeneration provides a suitable habitat for re-establishing wild turkey populations in the MAV. We translocated wild turkeys to two study sites in reforested areas of the MAV. We monitored 74 wild turkeys’ habitat use and resource selection using radio telemetry from February 2009 to June 2010. We developed land use and land cover maps for the resource selection analysis of translocated wild turkeys. We found that turkey habitat use varied by site, sex, season, land cover type, and distance to mature hardwoods. Habitat use by wild turkeys decreased as distance to mature hardwood forest increased. Female wild turkeys used more hardwood regeneration during nesting and post-nesting seasons than during pre-nesting seasons. Although wild turkeys did not use regenerating and mature hardwood forests to the same extent, management of these forests appears critical to restoring wild turkeys in the MAV.

Leaf acclimation to soil flooding and light availability underlies photosynthetic capacity of Lindera melissifolia, an endangered shrub of bottomland forests in the Mississippi Alluvial Valley, USA.

Lindera melissifolia is an endangered shrub indigenous to the broadleaf forest of the Mississippi Alluvial Valley (MAV). In this region, extant colonies of the species are found in periodically ponded habitats where a diversity of broadleaf trees can form well-developed overstory and sub-canopies-these habitat characteristics suggest that soil flooding and light availability are primary drivers of L. melissifolia ecophysiology. To understand how these two factors affect its photosynthetic capacity, we quantified leaf characteristics and photosynthetic response of plants grown in a large-scaled, field setting of three distinct soil flooding levels (no flood, 0day; short-term flood, 45days; and extended flood, 90days) each containing three distinct light availability levels (high light, 30% shade cloth; intermediate light, 63% shade cloth; and low light, 95% shade cloth). Lindera melissifolia leaves showed marked plasticity to interacting effects of flooding and light with lamina mass per unit area (Lm/a) varying 78% and total nitrogen content per unit area (Na) varying 63% from the maximum. Photosynthetic capacity (A1800-a) ranged 123% increasing linearly with Na from low to high light. Extended flooding decreased the slope of this relationship 99% through a reduction in N availability and metabolic depression of A1800-a relative to Na. However, neither soil flooding nor light imposed an additive limitation on photosynthetic capacity when the other factor was at its most stressful level, and the A1800-a-Na relationship for plants that experienced short-term flooding suggested post-flood acclimation in photosynthetic capacity was approaching the maximal level under respective light environments. Our findings provide evidence for wide plasticity and acclimation potential of L. melissifolia photosynthetic capacity, which supports active habitat management, such as manipulation of stand structure for improved understory light environments, to benefit long-term conservation of the species in the MAV.

Intensity and mode of Lindera melissifolia reproduction are affected by flooding and light availability.

We studied the impact of flooding and light availability gradients on sexual and asexual reproduction in Lindera melissifolia (Walt.) Blume, an endangered shrub found in floodplain forests of the Mississippi Alluvial Valley (MAV), USA. A water impoundment facility was used to control the duration of soil flooding (0, 45, or 90 days), and shade houses were used to control light availability (high = 72%, intermediate = 33%, or low = 2% of ambient light) received by L. melissifolia established on native soil of the MAV. Sexual reproductive intensity, as measured by inflorescence bud count, fruit set, and drupe production, was greatest in the absence of soil flooding. Ninety days of soil flooding in the year prior to anthesis decreased inflorescence bud counts, and 45 days of soil flooding in the year of anthesis lessened fruit set and drupe production. Inflorescence bud development was the greatest in environments of intermediate light, decreased in high‐light environments, and was absent in low light environments. But low fruit set diminished drupe production in intermediate light environments as compared to high light environments. Asexual reproduction, as measured by development of new ramets, was greatest in the absence of soil flooding and where plants were grown in high or intermediate light. Plants exhibited plasticity in reproductive mode such that soil flooding increased the relative importance of asexual reproduction. The high light environment was most favorable to sexual reproduction, and reproductive mode transitioned to exclusively asexual in the low light environment. Our results raise several implications important to active management for the conservation of this imperiled plant.

An inventory and typology of permanent floodplain lakes in the Mississippi Alluvial Valley: a first step to conservation planning

The alluvial valley of the Mississippi River is an extensive area harboring hundreds of lakes created by fluvial dynamics. These floodplain lakes are scattered throughout the valley and carved over thousands of years by shifting river courses and other hydro-fluvial processes associated with contemporary and prehistoric rivers. These lakes have significant ecological importance as they support a large component of North American biodiversity. We used remote sensing to catalog lakes, to characterize morphology, and to construct a typology via cluster analysis. We identified over 1300 permanent lakes totaling over 100,000 ha. The lakes were classified into 12 types according to lake size, shape, depth, connectivity, inundation frequency, and surrounding landcover. We anticipate that biotic characteristics differ among the 12 types, but large-scale systematic analyses of biotic assemblages of floodplain lakes in the region are mostly absent. Our typology can provide the framework essential for organizing research to define water dynamics, water quality, and ecological conditions such as forests, mussel, fish, and avian communities to construct conservation plans. The typology encourages a large-scale view of the properties of floodplain lakes in the alluvial valley. It is a functional tool that can be used to begin identifying conservation and research needs, adapt monitoring and management programs, customize environmental programs, and use conservation resources more effectively to achieve large-scale management objectives.

Low external input sustainable agriculture: Winter flooding in rice fields increases bird use, fecal matter and soil health, reducing fertilizer requirements

This study investigated a low-external-input sustainable-agriculture (LEISA) rice production system in the Mississippi Alluvial Valley (MAV) that applied ecological principles to create waterbird habitat and enhance soil fertility. Two production sites were selected for this study (LEISA and conventional). Each production site applied a flooded treatment and a fallow treatment to select fields during the non-growing season (November 2017- March 2018). Bird fecal matter inputs and soil microbial bacteria/activity and nutrient content were quantified and compared between fields. Significantly more % total nitrogen, % total carbon, microbial richness and activity (P < 0.05) were found in flooded LEISA than other study fields. Bird fecal matter inputs on LEISA flooded fields contributed an estimated 6.1–48.9 kg N/ha/season, whereas 1.9–14.8 kg N/ha/season were added to conventionally flooded fields. Long-term application of the unique LEISA rice farming system can reduce the need for synthetic fertilizer application by > 13 %, while increasing soil organic carbon. This case study provides a foundation for future research into the agronomic benefits of creating bird habitat in rice fields, while documenting how conservation strategies support agronomic production and sustainability to foster conservation adoption.

Temporal Trends in Body Condition of Arctic Geese Wintering in the Mississippi Alluvial Valley

Abstract Midcontinent populations of arctic nesting geese (hereafter, arctic geese), including greater white-fronted geese Anser albifrons frontalis, lesser snow geese Anser caerulescens caerulescens, and Ross's geese Anser rossii, have increased in abundance and shifted their winter distribution in recent decades. Consequently, the number of arctic geese wintering in the Mississippi Alluvial Valley (MAV) has increased since the 1980s. Stored endogenous nutrients are critically important to the life cycle of arctic geese as the geese use these stored nutrients to complete long-distance migration events, survive harsh winters, and supplement nutrients needed for reproduction. This study tracked temporal changes in body condition of arctic geese during the wintering period. We collected arctic geese from October–February 2015–2016 and 2016–2017 in eastern Arkansas. We used proximate analysis to determine size of lipid and protein stores as an index of body condition. Protein stores were more stable through time than lipids, but we observed a slight increase in all species as winter progressed. Mean lipid stores were dynamic and were highest in November and lowest in February. Greater white-fronted geese arrived earliest to the MAV and experienced an increase in endogenous lipid stores during early winter when high-energy food resources were most abundant. Conversely, snow and Ross's geese arrived to the MAV later and did not appear to increase their lipid stores upon arrival. All three species experienced a decline in stored lipid mass as winter progressed; a combination of factors such as resource depletion, a shift in dietary needs, physiological factors, hunting pressure, and increased energetic demands may have driven the decline. An improved understanding of the role that “nontraditional” wintering grounds exert on the nutrient dynamics of arctic geese may aid in the management of growing and shifting populations.

The importance of turtle populations to wetland restoration in the Upper Mississippi Embayment of the Mississippi Alluvial Valley

The Upper Mississippi Embayment (UME) ecoregion covers approximately 141,895 km2 and historically supported 9,712,455 ha of bottomland deciduous forests, swamps, bayous, and rivers. Only about 500 ha (< 0.01%) of pre-settlement bottomland hardwood forest habitat in the Mississippi Alluvial Valley (MAV) in the UME remained by the 1940s because the timber was clearcut and the wetlands drained for agriculture. By 1983 only a few scattered cypress-tupelo swamps remained. We studied the freshwater turtle community in Allred Lake, Missouri, a rare remnant of this ecosystem and compared these results to those from two other study sites in the MAV, Big Oak Tree State Park (BOTSP), Missouri, and Coldwater River National Wildlife Refuge (CRNWR), Mississippi. Species richness included six species commonly found throughout the MAV. One species (Red-eared Slider, Trachemys scripta elegans) dominated density and biomass in all three assemblages. The occurrence of the six species we studied in man-made restored wetlands such as those in BOTSP and CRNWR indicate these turtles would adapt to restored wetlands in the MAV in southeastern Missouri and elsewhere in the ecosystem. We provide information on habitat features that could be included in restoration design and construction that would benefit turtles. Given the ongoing worldwide decline of turtles, consideration of turtle ecology and behavior in wetland restoration projects in the MAV may be warranted.

Effects of landscape structure and temporal habitat dynamics on wintering mallard abundance

Management of wintering waterfowl in North America requires adaptability because constant landscape and environmental change challenges existing management strategies regarding waterfowl habitat use at large spatial scales. Migratory waterfowl including mallards (Anas platyrhynchos) use the lower Mississippi Alluvial Valley (MAV) for wintering habitat, making this an important area of emphasis for improving wetland conservation strategies, while enhancing the understanding of landscape-use patterns. We used aerial survey data collected in the Arkansas portion of the MAV (ARMAV) to explain the abundance and distribution of mallards in relation to variable landscape conditions. We used two-stage, hierarchical spatio-temporal models with a random spatial effect to identify covariates related to changes in mallard abundance and distribution within and among years. We found distinct spatio-temporal patterns existed for mallard distributions across the ARMAV and these distributions are dependent on the surrounding landscape structure and changing environmental conditions. Models performing best indicated seasonal surface water extent, rice field, wetland and fallow (uncultivated) fields positively influenced mallard presence. Rice fields, surface water and weather were found to influence mallard abundance. Additionally, the results suggest weather and changing surface water affects mallard presence and abundance throughout the winter. Using novel datasets to identify which environmental factors drive changes in regional wildlife distribution and abundance can improve management by providing managers additional information to manage land over landscapes spanning private and public lands. We suggest our analytical approach may be informative in other areas and for other wildlife species.

Nitrate Reduction in a Hydrologically Restored Bottomland Hardwood Forest in the Mississippi River Watershed, Northern Louisiana

Core Ideas River–floodplain connectivity is low in the Mississippi River basin. Floodplain restoration led to an increase in NO3 reduction from river water. Recovery of NO3 reduction was faster than other soil microbial measures. Nitrogen loading from the Mississippi River leads to formation of water column hypoxia in the northern Gulf of Mexico every summer. Bottomland hardwood (BLH) forests located within the Mississippi River watershed could play a crucial role in reducing NO3− loading to the Gulf of Mexico. However, much river–floodplain connectivity has been muted due to building of levees and land conversion for agriculture. Restoring floodplain–river connectivity can potentially reduce river NO3−. Mollicy Farms, a 6475‐ha BLH site in northern Louisiana, is the largest floodplain reconnection and BLH reforestation project in the Mississippi River Basin. Soil properties, including microbial measures (microbial biomass N, potentially mineralizable N, and β‐glucosidase activity) and NO3− reduction rates were compared with a control site. Nitrate reduction rates in the restored site were 28% lower than in the control site (11.8 ± 3.4 vs. 16.4 ± 8.1 mg N m−2 d−1), with the potential removal of ∼48.1 Mg of NO3–N from the Ouachita River annually. Other soil microbial measures, however, were &gt;50% lower in the restored site compared with the control site, demonstrating that NO3− reduction has responded more quickly to hydrologic reconnection. Therefore, NO3− reduction in restored floodplain wetlands may have a relatively more rapid trajectory of recovery, allowing hydrologic reconnection to be an effective tool for enhancing NO3− reduction in the Lower Mississippi alluvial valley and reducing N flux to the coastal ocean.

Harvest of crayfish as an ecosystem service of wetlands compared to production systems with planted forage

ABSTRACTCrayfish harvest as an ecosystem service of moist-soil wetlands in the Mississippi Alluvial Valley (MAV) was evaluated using estimates of crayfish yield and operational costs to create enterprise budgets. The average daily yield of crayfish was 2.13 lb/acre (95% CI = 1.19–3.00) and yield did not differ between wetlands dominated with Red Swamp Crayfish or White River Crayfish. Four hypothetical scenarios of harvest operations revealed annual costs associated with harvesting crayfish to be $163.89–370.75/acre. Although these costs were lower than estimated costs currently associated with harvesting crayfish from fields with planted forage in Louisiana ($749.96/acre), a three-fold reduction in crayfish yield (lb/trap/day) from moist-soil wetlands resulted in an increase in the break-even selling price from $1.25/lb in Louisiana to $1.70–$3.86/lb in the MAV. Although this enterprise will likely not compete with the Louisiana rice-crayfish industry, harvesting crayfish from moist-soil wetlands may contribute to ecosystem services provided by wetlands and aid in the reduction of the quantity of crayfish products imported into the U.S. market.

Census of the Delta State University woody plant community and its implications for ecosystem health

Native plant communities support a diverse biota of invertebrates, birds, and other wildlife, and are therefore essential to the health of ecosystems. Agriculture and urban development have eliminated most native plant communities through forest clearing and introduction of exotic, invasive plants. Prior to European settlement, bottomland hardwood forests prevailed along broad floodplains within the lower Mississippi alluvial valley. Dominant taxa included Taxodium distichum (L.) Rich. (bald cypress), Quercus spp. (oaks), Carya spp. (hickories), Fraxinus pennsylvanica (green ash), Liquidambar styraciflua (sweetgum), Celtis laevigata (sugarberry), Ulmus spp. (elms), and Nyssa spp. (gums). Much of this forested area, however, has been cleared and used for agricultural purposes or urban development. Bottomland hardwood forests, situated along the Mississippi River, are associated with the Mississippi Flyway, a bird migration route heavily utilized by migratory waterfowl, songbirds, and shorebirds for food, water, and shelter. In this preliminary study, woody plant species (trees and shrubs) occurring on the 134 hectare Delta State University campus (33°44.756′N, 90°44.026′W) were identified and documented. At present 46 families, 77 genera, and 125 species have been recognized. Only 66 species are native to the state of Mississippi. Only 41 species are native to the Mississippi Delta. We encourage the planting of more native woody plants representative of bottomland hardwood forests that will benefit migratory wildlife and enhance native habitat and food availability.

Shorebird Foraging Habitat in Southeast Arkansas

Approximately 500,000 shorebirds travel through the Mississippi Alluvial Valley (MAV) each spring and fall. During migration, the average 45g shorebird needs to eat approximately 8g of invertebrates per day. While shorebird stopover habitat guidelines for the MAV are based on an expert estimate of 2g of invertebrates/m2, this estimate has not been quantified in Arkansas. Invertebrate biomass available for shorebird foraging was examined on five properties in southeastern Arkansas during spring and fall migration (fall 2010, spring and fall 2011, and spring 2012). Macroinvertebrate biomass was less than the estimated 2 g/m2 in three of the four sampled seasons. Further validation of the expert invertebrate biomass estimate should be undertaken in the other regions of the MAV. These results suggest that current land management of shorebird stopover habitat in southeastern Arkansas is not providing adequate invertebrate forage to reach the current habitat management goals.

Spatial patterns of lacustrine fish assemblages in a catchment of the Mississippi Alluvial Valley

ABSTRACTIn the alluvial valley of the lower Mississippi River, floodplain lakes form isolated aquatic fragments that retain differing degrees of connectivity to neighbouring rivers. Within these floodplain lakes it was hypothesized that fish species composition, relative abundance, and biodiversity metrics would be shaped largely by aquatic connectivity within a catchment.Fish assemblages in 13 floodplain lakes (five on‐channel; eight off‐channel) were assessed with electrofishing in 2006–2012 in the Bear Creek catchment, Mississippi, USA. Bear Creek spans approximately 80 km before draining into the Yazoo River, a tributary of the Mississippi River.Fish assemblages in on‐channel and off‐channel lakes were different, and fish assemblages in on‐channel lakes were as a group more homogeneous than off‐channel lakes. Moreover, a longitudinal gradient in fish assemblages occurred in on‐channel lakes. The observed patterns in fish assemblages are linked largely to differing intensities in connectivity among lakes within the catchment. Lakes with irregular connections have greater individuality, whereas lakes with continuous or chronic connection are more similar. The wide variation in connectivity could be a key to the distinctive biodiversity of catchments and the focus of fish conservation programmes.Off‐channel floodplain lakes are among the first landscape elements to vanish as a consequence of agricultural development. These habitats tend to accumulate sediments at fast rates and are converted to agricultural land as soon as suitable drainage can be attained. Considering that off‐channel lakes with limited connectivity contribute greatly to the heterogeneity of fish assemblages, such losses pose great concerns to conservation of biodiversity. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

Comprehensive Framework for Ecological Assessment of the Migratory Bird Habitat Initiative Following the Deepwater Horizon Oil Spill

Abstract Following the Deepwater Horizon oil spill in the Gulf of Mexico in April 2010, the USDA Natural Resources Conservation Service (NRCS) established and funded the Migratory Bird Habitat Initiative (MBHI), with the goal of improving and increasing wetland habitats on private lands to benefit wintering and migrating waterbirds displaced from oil-impacted coastal wetlands. The NRCS and conservation partners provided financial and technical assistance to landowners and managers of sites enrolled in various conservation easement programs, and incorporated approximately 190,000 ha of wetlands and agricultural lands in the Mississippi Alluvial Valley (MAV) and Gulf Coast regions in the MBHI. In fall 2010, the NRCS worked with scientists and graduate students from three universities and various conservation agencies to design and implement landscape-scale evaluations of (1) the use of MBHI-managed wetlands and comparable non-MBHI wetlands by Charadriiformes (shorebirds), Anseriformes (waterfowl), and other...

Centrarchid Assemblages in Floodplain Lakes of the Mississippi Alluvial Valley

AbstractThe family Centrarchidae is a principal and visible component of the ichthyofauna in most warmwater ecosystems in North America, and many of its species provide key recreational fisheries. We examined the significance of various local environmental factors to 13 centrarchid species in 53 floodplain lakes (remnant channels) of the Mississippi alluvial valley to identify major environmental gradients influential in structuring centrarchid assemblages. With few exceptions, changes in forest representation in the land cover, both in the lakeshore and the catchment, had the strongest associations with centrarchid assemblages. Other influential factors included depth, water clarity, and primary productivity. Connectivity to adjacent streams was weakly correlated with centrarchid assemblage structure and correlated only with a small number of species. Lake area did not appear to affect centrarchid assemblages. Recognition that land cover has the strongest correlation with centrarchid assemblage composition suggests a landscape basis for developing management plans. However, conservation and restoration of native centrarchid assemblages in these unique ecosystems will require both watershed management to curtail inputs and in‐lake management to reverse years of neglect.

Winter waterbird and food dynamics in autumn‐managed moist‐soil wetlands in the Mississippi Alluvial Valley

AbstractManaged moist‐soil wetlands are important habitats for waterfowl and other waterbirds in the Mississippi Alluvial Valley (MAV) and elsewhere in North America. These wetlands often contain abundant food resources, but they also contain tall and dense (i.e., robust) vegetation that may constrain use and foraging by waterbirds. During winters 2006–2009, we estimated densities of waterbirds, seeds and tubers, and aquatic invertebrates following autumn, preflooding treatments of disking, mowing, and no manipulation (control) of robust vegetation in 26 moist‐soil wetlands in and near the MAV. In late autumn, seed and tuber dry mass was greater in control (${\bar {x}}$ = 750.7 kg/ha) and mowed (${\bar {x}}$ = 709.7 kg/ha) than disked plots (${\bar {x}}$ = 509.8 kg/ha). Dabbling ducks (Anatini) accounted for 92% of all waterbirds observed and were 2–3 times more abundant in mowed and disked than control plots during winter. Invertebrates comprised &lt;1% (dry mass) of potential waterbird foods, but were greatest in control plots throughout winter. In mid‐ and late winter, residual seed and tuber masses were similar among mowed, disked, and control plots within study sites (approx. 260 kg/ha), despite different waterbird use. We recommend 1) active management of moist‐soil wetlands, including partial autumn mowing of robust vegetation to increase use by waterbirds; 2) that conservation planners consider increasing foraging thresholds (e.g., giving‐up density) in carrying‐capacity models for moist‐soil wetlands; and 3) additional experiments to describe foraging thresholds in moist‐soil and other wetlands targeted by the North American Waterfowl Management Plan. © 2012 The Wildlife Society.

Vegetative Forage Quality and Moist-soil Management on Wetlands Reserve Program Lands in Mississippi

The Wetland Reserve Program (WRP) prescribes management of vegetation in moist-soil wetlands for waterfowl and other wildlife. This study used a block design on 18 sites in the Mississippi Alluvial Valley (MAV) in Mississippi to evaluate effectiveness of management prescriptions. Objectives were to determine appropriate timing of vegetation surveys and whether vegetation community metrics on private lands differed among management strategies (2008–2009): 1) active (e.g., annual soil disturbance), early drawdown of standing water (i.e., by 15 June), 2) active, late drawdown (≥3 weeks after early drawdown), and 3) passive, natural evaporation. A Vegetative Forage Quality Index (VFQI) was developed to assess quality of plant communities as forage for waterfowl. The study examined VFQI, plant community diversity and richness, percent (%) occurrence of grass, % woody species, and mean number of plant life-forms among management categories (α = 0.10). Plant community metrics were measured June–October but only October metrics revealed differences in both years (p ≤ 0.09). Active-early had the greatest VFQI, diversity, mean number of plant life-forms, and percent abundance of grasses in October 2008 and 2009 (p ≤ 0.07). Results suggest that quality forage for waterfowl may be achieved through active management with early draw-down.

A Quantitative Assessment of the Conservation Benefits of the Wetlands Reserve Program to Amphibians

AbstractThe Mississippi Alluvial Valley (MAV) originally consisted of nearly contiguous bottomland hardwood (BLH) forest encompassing approximately 10 million hectares. Currently, only 20–25% of the historical BLH forests remain in small patches fragmented by agricultural lands. The Wetlands Reserve Program (WRP) was established to restore and protect the functions and values of wetlands in agricultural landscapes. To assess the potential benefit of WRP restoration to amphibians, we surveyed 30 randomly selected WRP sites and 20 nearby agricultural sites in the Mississippi Delta. We made repeat visits to each site from May to August 2008 and performed both visual encounter and vocalization surveys. We analyzed the encounter history data for 11 anuran species using a Bayesian hierarchical occupancy model that estimated detection probability and probability of occurrence simultaneously for each species. Nine of the 11 species had higher probabilities of occurrence at WRP sites compared to agriculture. Derived estimates of species richness were also higher for WRP sites. Five anuran species were significantly more likely to occur in WRP than in agriculture, four of which were among the most aquatic species. It appears that the restoration of a more permanent hydrology at the WRP sites may be the primary reason for this result. Although amphibians represent only one group of wildlife species, they are useful for evaluating restoration benefits for wildlife because of their intermediate trophic position. The methods used in this study to evaluate the benefit of restoration could be used in other locations and with other groups of indicator species.

Apparent seed use by ducks in moist‐soil wetlands of the Mississippi Alluvial Valley

AbstractScientists, conservation planners, and resource managers who estimate energetic carrying capacity of foraging habitats for wintering waterfowl require accurate data on food availability and use. We estimated seed and tuber abundance in moist‐soil wetlands commonly used and foraged in by dabbling ducks (Anas spp.) in and near the Mississippi Alluvial Valley (MAV). To identify foods potentially used by dabbling ducks, we surveyed food‐use literature from studies conducted in or near the MAV and compared estimated seed decline rates from core samples to predicted decline rates using published and measured estimates of decomposition. We inferred seed use when observed declines in mass exceeded that predicted by decomposition. In our analyses, we identified 15 taxa of moist‐soil seeds apparently used and 6 taxa apparently not used by dabbling ducks. From our analyses and literature review, we identified 25 taxa of moist‐soil seeds and tubers commonly consumed and apparently used by dabbling ducks in or near the MAV. Removal of seeds apparently not used by dabbling ducks resulted in a 30.9% (SE = 1.3) reduction in estimates of seed and tuber mass in managed moist‐soil wetlands in the MAV. When we retained 3 seed taxa reported by previous studies as consumed by dabbling ducks, but which did not decline faster than predicted in our experimental wetlands, seed and tuber estimates were reduced by 26.8% (SE = 1.3). Inclusion of seeds not consumed by dabbling ducks in models of carrying capacity would result in overestimation of existence energy days by the Lower Mississippi Valley Joint Venture and underestimation of moist‐soil habitat requirements in the MAV. We suggest scientists conduct food‐use and selection studies by collecting actively foraging ducks in the MAV to confirm our results and increase accuracy of carrying capacity estimates for dabbling ducks in autumn and winter. © 2011 The Wildlife Society.

Phenology of Shorebird Migration in Western Kentucky

Staging areas along the coasts provide reliable food resources, and shorebirds may use the same stopover locations every year. However, shorebirds use sites opportunistically in the interior of North America because of the transient nature of many habitats. Little is known, however, about the use of wetlands by migrating shorebirds in many areas of the Mississippi Alluvial Valley (MAV), including Kentucky. During 2004 and 2005, we examined the phenology of migration by shorebirds using stopover habitats in Kentucky. From March to October, we surveyed shorebirds in each moist soil unit as well as at other natural and man-made wetlands at each wildlife management area. Species abundance was recorded a minimum of once every 10-day period. We observed 25 species and 12,307 individual shorebirds during our study, with Charadrius vociferous (Killdeer; n = 4134), Calidris melanotos (Pectoral Sandpiper; n = 2912), Calidris minutilla (Least Sandpiper; n = 1138), Tringa melanoleuca (Gmelin) (Greater Yellowlegs; n = 942), and Tringa flavipes (Lesser Yellowlegs; n = 911) being most abundant. We observed nearly 75% more shorebirds during fall migration than during spring migration, possibly because less suitable habitat is available in the fall and shorebirds concentrate in those areas. In addition, shorebird migration extended over a longer period in the fall than in the spring, a pattern that likely results because adults migrate earlier in the fall and juveniles migrate later. Our results provide additional evidence that the MAV provides important stopover habitat for many species of shorebirds during both spring and fall migration.