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Justification for investment in restored or constructed wetland projects are often based on presumed net increases in ecosystem services. However, quantitative assessment of performance metrics is often difficult and restricted to a single objective. More comprehensive performance assessments could help inform decision-makers about trade-offs in services provided by alternative restoration program design attributes. The primary goal of the Iowa Conservation Reserve Enhancement Program is to establish wetlands that efficiently remove nitrates from tile-drained agricultural landscapes. A secondary objective is provision of wildlife habitat. We used existing wildlife habitat models to compare relative net change in potential wildlife habitat value for four alternative landscape positions of wetlands within the watershed. Predicted species richness and habitat value for birds, mammals, amphibians, and reptiles generally increased as the wetland position moved lower in the watershed. However, predicted average net increase between pre- and post-project value was dependent on taxonomic group. The increased average wetland area and changes in surrounding upland habitat composition among landscape positions were responsible for these differences. Net change in predicted densities of several grassland bird species at the four landscape positions was variable and species-dependent. Predicted waterfowl breeding activity was greater for lower drainage position wetlands. Although our models are simplistic and provide only a predictive index of potential habitat value, we believe such assessment exercises can provide a tool for coarse-level comparisons of alternative proposed project attributes and a basis for constructing informed hypotheses in auxiliary empirical field studies. [ABSTRACT FROM AUTHOR]

Resource managers confronted with preserving ecosystems for prairie wetland birds in fragmented landscapes require landscape studies thatdirect conservation efforts over broad geographic regions. We investigated the role of local and landscape factors affecting habitat suitability by integrating remotely sensed wetland and land-cover data with wetland bird habitat models. We linked habitat models with locations of easement and fee-title wetlands to evaluate spatial location and extent of protected, suitable habitat. We also simulated impacts ofthe loss of small wetlands on suitability of larger wetlands for mobile species that use multiple wetlands. Lastly, we evaluated the efficacy of waterfowl habitat programs in preserving suitable habitat fornongame wetland bird species to recommend strategies for maximizing regional landscape connectivity. Regional databases constructed for this study indicate that easement and fee-title tracts encompass 13.9%(1.2 million ha) of land area and protect 19.8% of the wetlands in eastern South Dakota, USA. Proportion of protected wetlands is highestfor semi-permanent (32.3%), intermediate for seasonal (25.6%), and lowest for temporary wetlands (15.8%). A stratified, two stage clustersample was used to randomly select 834 semi-permanent and seasonal wetlands that were surveyed for birds in 1995 and 1996. Logistic analyses indicate that habitat suitability for some species (e.g., Virginia rail, pied-billed grebe) is related to local vegetation conditions within wetlands, while suitability for others (e.g., northern pintail, black tern) is related to landscape structure at larger scales. As a result, unfragmented prairie wetland landscapes (i.e., areas with wetland complexes embedded within upland grasslands) provide habitat for more species than isolated wetlands in tillage fields. Models developed from survey wetlands were used to classify habitat suitability for all semi-permanent and seasonal wetlands in eastern South Dakota.Small [ABSTRACT FROM AUTHOR]

The U.S. Fish and Wildlife Service and Canadian Wildlife Service incorporate information from annual aerial and ground counts of waterfowl into harvest management strategies. Timing of population surveys isthought to be optimal for early nesting species but may not reliablyreflect the status of species with later migration chronology. The purpose of this study was to evaluate effects of survey timing on diving duck and duck brood abundance indices in eastern South Dakota. Findings indicate that timing of aerial breeding surveys occurred too early in eastern South Dakota to accurately reflect diving duck population status because birds had not yet settled into breeding habitats and aerial production surveys did not coincide with peak duck brood abundance. Diving duck abundance from aerial surveys conducted during 10-17 May were higher than indices from ground surveys conducted 2 weeks later because lesser scaup (Aythya affinis), ring-necked duck (Aythya collaris), and bufflehead (Bucephala albeola) were still migrating through eastern South Dakota. Ground-survey estimates of redhead (Aythya americana) and canvasback (Aythya valisineria) abundance exceeded the upper limit of 95% confidence intervals for aerial survey estimates. Results from our second year of study showed an 11-fold decrease in lesser scaup abundance and an 8-fold decrease in ring-necked duck abundance in the two weeks following aerial breeding surveys. Brood abundance of dabbling and diving ducks peaked 1-1.5 months after aerial production surveys conducted in early July. Late-nesting indicescalculated from aerial surveys were unrelated (P = 0.21) to number of late-hatching broods, whereas number of broods hatching after aerial surveys was correlated with late-nesting indices from ground surveys (r2 = 0.74, P < 0.01) and with number of July ponds (r2 = 0.77, P < 0.01). We encourage scientists to initiate a more thorough evaluation of survey biases to ensure that trends accuratel [ABSTRACT FROM AUTHOR]

Estimates of number of wetlands derived from quadrat sampling are inherently biased when wetlands on quadrat boundaries are counted. Biascomplicates comparisons of wetland density or abundance between years or studies, or between regions with different wetland sizes. Simulated quadrat sampling was conducted to evaluate the magnitude of bias in estimates of the number of temporary, seasonal, semipermanent, andtotal wetlands from samples of square quadrats of different sizes. All estimates were biased except for number of temporary wetlands derived from samples of the largest quadrats. Bias ranged from +101% (SE = 0.39%) for estimates of the number of semipermanent wetlands sampled with 0.64 km2 quadrats to +0.19% (SE = 0.19%) for the number of temporary wetlands sampled with 25.60 km2 quadrats. Bias was greatest when large wetlands were sampled using small quadrats and was related to quadrat perimeter:area ratio (km/km2) and to quadrat size. Managersand researchers should correct for bias in estimates of number of wetlands by deriving correction factors with the equations presented orby deriving corrections factors using aerial photographs to determine the geometric centers of wetlands in and around a subset of sample quadrats. [ABSTRACT FROM AUTHOR]