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Global climate change is increasing the frequency and severity of extreme climatic events (ECEs) which may be especially detrimental during late-winter when many species are surviving on scarce resources. However, monitoring animal populations relative to ECEs is logistically challenging. Crowd-sourced datasets may provide opportunity to monitor species' responses to short-term chance phenomena such as ECEs. We used 14 years of eBird-a global citizen science initiative-to examine distribution changes for seven wintering waterfowl species across North America in response to recent extreme winter polar vortex disruptions. To validate inferences from eBird, we compared eBird distribution changes against locational data from 362 GPS-tagged Mallards (Anas platyrhynchos) in the Mississippi Flyway. Distributional shifts between eBird and GPS-tagged Mallards were similar following an ECE in February 2021. In general, the ECE affected continental waterfowl population distributions; however, responses were variable across species and flyways. Waterfowl distributions tended to stay near wintering latitudes or moved north at lesser distances compared with non-ECE years, suggesting preparedness for spring migration was a stronger "pull" than extreme weather was a "push" pressure. Surprisingly, larger-bodied waterfowl with grubbing foraging strategies (i.e., geese) delayed their northward range shift during ECE years, whereas smaller-bodied ducks were less affected. Lastly, wetland obligate species shifted southward during ECE years. Collectively, these results suggest specialized foraging strategies likely related to resource limitations, but not body size, necessitate movement from extreme late-winter weather in waterfowl. Our results demonstrate eBird's potential to monitor population-level effects of weather events, especially severe ECEs. eBird and other crowd-sourced datasets can be valuable to identify species which are adaptable or vulnerable to ECEs and thus, begin to inform conservation policy and management to combat negative effects of global climate change.

The Mississippi Flyway supports millions of waterfowl during spring migration as individuals replenish vital nutrients en route to breeding locations. Green-winged teal Anas crecca consume natural plant and animal foods in shallow wetlands during autumn and winter, but little information is available to describe food use and selection during spring migration. We experimentally collected green-winged teal and quantified food use and availability to determine selection in the Illinois River Valley during February–April 2016–2018. We removed, dried, and weighed (±0.1 mg) food items by taxa from the upper digestive tract (proventriculus and esophagus) of birds and core samples for comparison. Additionally, we evaluated retention of common diet items between small (#60; 250 μm) and medium (#35; 500 μm) sieves and the effect of processing sieve size on selection coefficients. Seeds of moist-soil vegetation occurred in all green-winged teal diets, while invertebrates and vegetation material occurred in 67.4% and 25.8% of diets, respectively. Green-winged teal consumed 85.8% (CI95 = 81.2–90.3%) plant material and 14.2% (CI95 = 9.6–18.7%) invertebrates based on aggregate dry biomass. We failed to find support for selection of either plant or animal foods in general, but green-winged teal selected Cyperus spp., Ammannia spp., Leptochloa spp., and Potamogeton spp. and avoided Amaranthus spp., Ipomoea spp., Echinochloa spp., and Oligochaeta individual taxa. We found no support for a difference in selection ratios between sexes, but selection ratios differed among years and wetland connectivity regimes with changes in food availability. Sieve size had minimal impact on rank and selection intensity of most food items, but only small sieves captured Ammannia spp., which was an important diet item. We found no evidence that green-winged teal selected invertebrates in our midlatitude migration study area, as has been speculated for dabbling ducks in general during spring migration (i.e., spring diet-shift hypothesis). We encourage managers to provide shallowly flooded wetlands with desirable plant taxa (e.g., Cyperus spp., Ammannia spp., Leptochloa spp.) for green-winged teal by maintaining actively managed moist-soil wetlands that are made available during spring migration.

Federal, state, and private entities manage seasonal flooded, shallow wetlands to provide food and other habitat resources for wetland-dependent migratory birds, including migrating and wintering waterfowl. Individual National Wildlife Refuges managed by the U.S. Fish and Wildlife Service annually monitor seed production in moist-soil wetlands to track performance relative to regional foraging habitat objectives and to evaluate local habitat management activities. The National Wildlife Refuge System does not currently have a standard sampling protocol, and thus seeks a reliable rapid assessment method for estimating seed production to achieve standardized estimates and to avoid inconsistencies in data collection, metrics used, and usefulness of the monitoring efforts. We compared seed yield estimates derived from a suite of commonly used seed production assessment methods with those from soil core samples across six National Wildlife Refuges in the southeastern United States. The most parsimonious model included only common plant species and a single visual assessment of overall coverage (1–5) and seed quality (1–4) for each moist-soil unit (r2adj = 0.71). Generally, models that included only common plant species and a visual estimate of seed yield for moist-soil wetlands overall had greater support than models that included all plant species and those that included data from subplots (n = 10) nested within moist-soil wetlands. Experience level of observer had a moderate effect on accuracy (r2mar = 0.20) and geographic range increased variation in overall seed yield estimates within moist-soil wetlands. Notably, we found that similar indices developed in different geographic regions performed well across the Southeast, but a widely used index based on estimates of seed yield for individual plant species performed poorly in this study. Standardizing the use of a single, efficient, and reliable method to estimate seed abundance in moist-soil wetlands will provide wetland mangers the ability to consistently estimate performance relative to objectives, evaluate management actions, and track trends on National Wildlife Refuges in the southeastern United States.

Wetland-dependent bird populations may be limited by habitat in regions where wetland loss and degradation are pervasive, such as the midwestern United States. However, available spatial datasets, such as the National Wetlands Inventory (NWI), may overestimate habitat availability if total wetland area includes wetlands unsuitable for wetland-dependent species. During 2016–2017, we assessed proportional coverages of wetland vegetation and inundation depth typically associated with suitable waterbird habitat relative to the NWI. We also modeled these data as a function of local and landscape characteristics during spring, summer, and autumn for three guilds of wetland-dependent, migratory birds. Suitable waterbird habitat conditions based on actual wetland characteristics measured comprised a small portion of the NWI. Shallowly inundated (

Spring migration is an energetically demanding event that can impact nutrient dynamics of individuals during the breeding season through carry-over effects. Limited food availability at spring stopover areas may have cross-seasonal effects that adversely impact waterfowl populations. We collected 161 Green-winged Teal (Anas crecca Linnaeus, 1758; hereafter Teal) throughout the Illinois River Valley, USA, during February–April of 2016–2018 and estimated body condition using three condition indices (scaled mass index, scaled wing index, body-size index) for comparison with carcass lipid and protein values. Lipids were 18.3% (95% CI = 1.0%–38.5%) and 21.6% (95% CI = 4.8%–41.0%) greater at locations with moderate (250–600 kg/ha) and high (>600 kg/ha) moist-soil seed densities, respectively, than low moist-seed density (

Intensification of land use practices and climate change have resulted in extensive wetland loss and declines of native submersed aquatic vegetation (SAV) species across North America. Limited by a lack of biomass and energy estimates for wetlands containing SAV, conservation planners currently are unable to accurately account for its energetic contribution in bioenergetics models for waterfowl and other waterbirds. Therefore, we estimated energetic carrying capacity of 21 semi-permanent wetlands containing SAV and identified as important stopover locations for migrating waterfowl and other waterbirds in the Midwest, USA during 2015–2017. Energy density of SAV ( $$ \overline{x} $$ = 813 ± 257 EUD/ha) was generally less than managed emergent wetlands, varied by National Wetland Inventory class, and had large annual (98–4873 ΔEUD/ha) and spatial variation (8–7971 EUD/ha). We developed a visual rapid assessment index (R2m = 0.43) that may be useful to wetland managers or researchers to quickly index energy density from SAV in semi-permanent wetlands. Energetic carrying capacity of wetlands containing SAV will allow conservation planners to more precisely estimate energy supply on the landscape for waterfowl and evaluate trade-offs among alternative management strategies. Our results demonstrate negative effects of hydrologic connectivity on SAV communities in highly modified landscapes.

Although most emergent wetlands across central North America have been destroyed or degraded, wetland restoration in recent decades has provided new habitat resources for wetland birds in agriculturally dominated landscapes. The goals of wetland restorations often include providing habitat for migratory and breeding waterfowl and other wetland birds. One such restored wetland complex in the Illinois River Valley, the Emiquon Preserve, is isolated from most flooding events of the Illinois River allowing the growth of persistent emergent vegetation that was quickly colonized by breeding wetland birds. We examined nest occurrence and variables influencing site selection, nest success, and changes in nest density across stages of the wetland succession cycle. We located 327 nests from nine species of wetland birds (American Bittern, Botaurus lentiginosus; American Coot, Fulica americana; Black-crowned Night-Heron, Nycticorax nycticorax; Black-necked Stilt, Himantopus mexicanus; Common Gallinule, Gallinula galeata; Green Heron, Butorides virescens; Least Bittern, Ixobrychus exilis; Pied-billed Grebe, Podilymbus podiceps; Sora, Porzana carolina) during 2013-2019. Common Gallinules were more likely to nest in persistent emergent vegetation than other cover types. American Coots and Least Bitterns selected nest sites based on water depth. Black-necked Stilt and Black-crowned Night-Heron nests were less successful in deeper water. Black-necked Stilt, Black-crowned Night-Heron, and Common Gallinule nests were less successful with later initiation dates. Nest density did not vary between persistent emergent and hemi-marsh cover types. Across 2013-2019 we estimated an average of 372 nests/year for six marsh-nesting bird species at Emiquon, including two state-endangered (Common Gallinule and Black-crowned Night-Heron) and one state-threatened (Least Bittern). Wetlands restored from agricultural fields can quickly provide critical breeding habitat for marsh-nesting birds of conservation concern, although continued management is needed to provide resources to maintain persistent emergent vegetation communities as individual marshes transition through the marsh cycle.

Energy acquisition and storage are important for survival and fecundity of birds during resource-limited periods such as spring migration. Plasma-lipid metabolites (i.e. triglyceride [TRIG], β-hydroxybutyrate [BOHB]) have been used to index changes in lipid stores and, thus, have utility for assessing foraging habitat quality during migration. However, such an index may be affected by energetic maintenance costs, diet, and other factors, and further validation under experimental conditions is needed to understand potential sources of variation and verify existing indices. We evaluated a plasma-lipid metabolite index using 30 female and 28 male wild Lesser Scaup (Aythya affinis; hereafter scaup) held in short-term captivity (∼24 hr) during spring migration. Similar to previous observational studies, BOHB was negatively associated and TRIG was positively associated with mass change (R2 = 0.68). BOHB estimates were nearly identical to those published on free-living scaup, but TRIG estimates differed from free-living scaup and varied by sex, with females having a greater rate of predicted mass change than captive and free-living males. Our results suggest TRIG may be a better measure of energy income than deposition because lipid deposition likely varies with energetic maintenance costs, stress, and underlying physiological processes while TRIG relates primarily to energy income. In contrast, BOHB was a reliable predictor of negative mass change across sexes. The sex-based differences in apparent lipid deposition rates warrant further research before a generalizable model is advisable for comparing mass change predictions across studies. However, if predictions are standardized, this technique is generally robust to variations in energy income vs. lipid deposition across sexes. Accordingly, our evaluation provides verification for the utility of plasma-lipid metabolites as an indicator of foraging habitat quality during migration.LAY SUMMARYThe past several decades have seen a growing body of literature on the utility of plasma-lipid metabolites to assess habitat quality for a multitude of migratory bird species.Research in this area is often focused on 2 key metabolites, β-hydroxybutyrate and triglyceride and their associated relationships with mass change.Triglyceride has a positive relationship with mass change and is often referred to as an indicator of lipid deposition or fattening rates. However, energetic maintenance costs may confound the relationship of triglycerides and lipid deposition.To the best of our knowledge, no studies have attempted to control for potential variation in energy expenditure in conjunction with metabolite sampling during migration.Thus, we believe our paper will be a useful addition to the scientific literature on these metabolites and will be of interest to a broad audience of national and international wildlife managers and avian researchers.

Numerous organisms exhibit carry-over effects, in which previous environmental conditions impact current performance. For example, reproductive output for many migratory birds can be impacted by events during the preceding migration. Lesser Scaup (Aythya affinis (Eyton, 1838); hereafter scaup) declined dramatically during 1970s–2000s, and there is evidence linking reduced reproductive output to reduced body condition during spring migration. In addition to food availability and quality, haemosporidian parasites (Plasmodium spp., Haemoproteus spp.) may be associated with condition of spring-migrating birds. We examined whether haemosporidian parasite infection status was linked to measures of size (mass, wing length, tarsus length, and keel length) and condition (body fat, size-corrected mass, wing-loading) in female spring-migrating scaup. Infection prevalence varied by year (21.7% in 2014; 47.1% in 2015) and percent body fat was negatively associated with the probability of infection. Body fat levels declined from 2014 to 2015, but at a similar rate for infected and uninfected birds. This pattern suggests that the increased prevalence in 2015 may have been related to the greater proportion of poor-condition birds being more susceptible to infection or recrudescence of latent infections. In light of forecasted range shifts and expansions of avian malaria vectors, the impact of haemosporidian parasites on migratory waterfowl condition warrants further investigation.

Some fish are important dispersal vectors of aquatic plants (i.e., ichthyochory), yet few examples have been documented outside of the Neotropics. Although highly modified and degraded, the upper Illinois River Waterway supports common carp (Cyprinus carpio) populations and abundant aquatic vegetation. As common carp have been previously documented to consume aquatic vegetation seeds, we assessed diets to determine the potential for common carp to function as dispersal vectors for aquatic vegetation seeds that may be important for restoration of rivers and floodplain wetlands. Whole seeds occurred at a high frequency and 42 seed taxa were discovered in the digestive system of common carp. Electivity analysis indicated that most seeds present were incidentally ingested; however, common carp diets contained seeds of wild celery (Vallisneria americana) at rates greater than expected by random chance. Our study indicates common carp may fill a similar functional role of seed dispersal for aquatic plant communities in temperate large river systems as they do for fruiting plants in the Neotropics. Our results highlight an understudied aspect of temperate freshwater ecology – fish as a potential influence on plant dynamics and resources in rivers. Fish-mediated seed dispersal has important but poorly understood implications and should be further explored.

Winter distribution and resource use of animals is driven by myriad interacting biotic and abiotic factors. Urban areas provide sanctuaries from hunting for game animals and may have thermal benefits during winter through reduced thermoregulatory costs. We deployed cellular GPS transmitters affixed to neck collars of 41 Canada Geese (Branta canadensis) in the Greater Chicago Metropolitan Area (GCMA) of northeastern Illinois, USA, to determine habitat selection and survival during autumn and winter. Canada Geese selected green spaces (59.8%) in greater proportion than available (14%), but they also regularly used industrial urban habitats such as rooftops and rail yards (11.3%), which has not been previously reported. Use of green spaces (−55.8%) decreased and use of industrial urban (+11.4%), riverine (+23.8%), and deep-water habitats (+140.7%) increased as temperatures dropped below the lower critical temperature for Canada Geese (i.e. the temperature at which increased thermoregulatory costs ar...

Probability-based sampling designs for aerial surveys are useful for estimating wintering waterfowl abundances in large areas with contiguous habitat (e.g., Mississippi Alluvial Valley). The effectiveness of these approaches for estimating abundance of nonbreeding waterfowl in small areas with discontinuous habitat has rarely been assessed. Surveys conducted within riverine areas introduce sampling design difficulties because of discontinuous bottomland habitat and irregularity of flooding events. Therefore, we implemented and evaluated a generalizable grid-based, stratified random sampling design to estimate weekly duck abundance within the Wabash River floodplain in southeastern Illinois and southwestern Indiana, USA, during midwinter and early spring 2012 and 2013. We used aerial and ground-based counts to generate abundance estimates and evaluate within-week variation of counts. Peak duck abundance totaled 279,717 (SE = 69,101) in 2012 and 742,027 (SE = 296,563) in 2013. Dabbling ducks were the most abundant duck guild detected and abundance estimates for this group met our precision goal (CV ≤ 0.25) in 4 of 18 surveys (x¯ = 0.33, range = 0.20–0.51). We compared the grid-based approach with a traditional aerial inventory and found that estimates from the grid-based approach were on average 75,175 (SE = 46,768) greater than inventory counts. Desired levels of precision were often not met, yet design improvements in 2013 notably increased precision, suggesting that further modifications may allow this method to be useful in riverine areas with discontinuous and ephemeral habitat. © 2017 The Wildlife Society.

The Illinois River Valley (IRV) in central Illinois, USA, provides migratory stopover habitat for millions of waterfowl during autumn and spring in the Mississippi Flyway. Mallards (Anas platyrhynchos) are the most abundant species of waterfowl during autumn migration and the most harvested duck in Illinois. We investigated mallard migration ecology in central Illinois, USA, to address information needs of biologists and managers in the Upper Mississippi River and Great Lake Region Joint Venture and Illinois Department of Natural Resources. Our objectives were to document daily movements and identify factors affecting inter-wetland movements, investigate lengths of foraging flights, assess home range size during stopover, describe habitat use and identify factors associated with wetland use, estimate survival and cause specific mortality, and evaluate proportional use of refuges and areas open to hunting in and nearby the IRV by mallards. We employed standard radio-telemetry techniques to achieve our objectives during autumns and early winters 2009 and 2010 (n = 86 F and 56 M mallards). The mean movement distance between locations collected on consecutive days was 2,822 ± 120 (SE) m (n = 1,862; max. = 56,966 m) across age, sex, and months. Female mallards (n = 35) traveled 2,708 ± 191 m during evening foraging flights (n = 145) to agricultural fields and emergent marshes. Mean home range size (95% minimum convex polygon) was 21,306 ± 1,925 ha across sex and age classes (n = 81 mallards). We documented 43 mortalities of 142 radio-marked mallards (2009: 28.2%; 2010: 32.3%) with 85.0% and 69.6% of deaths attributed to hunting in 2009 and 2010, respectively. Body condition, hunting period, age, year, minimum daily temperature, and daily movement distance were important variables affecting survival, but differences were most pronounced for year and hunting period. Overall survival was greater in 2010 (Ŝi = 0.62) than 2009 (Ŝi = 0.39) and daily survival rates were 0.8% and 0.4% greater during closed than open hunting periods in 2009 and 2010, respectively. Mallards used open water most frequently across years (49.4% daily locations), followed by corn (dryland, flooded, standing, or harvested; 16.3%), herbaceous (10.6%), woody (10.5%), and other wetlands and upland cover types. Use of areas closed to hunting was low (18.7%) and most diurnal locations of mallards occurred in wetlands open to hunting (81.3%; i.e., not designated as refuge by statute). Similar to diurnal habitat use, female mallards returning from evening foraging flights (n = 138) used areas open to hunting (81.9%) more than refuges (18.1%). Refuges that were primarily composed of open water received low use by autumn-migrating mallards in the IRV. Restoration or rehabilitation of moist-soil and emergent wetlands within statutory refuges protected from unnatural flood regimes may improve foraging habitat quality and increase survival for mallards and other ducks during migration. © 2017 The Wildlife Society.

Western Tennessee is an important region for waterfowl during non-breeding periods, supporting >40% of the Mississippi Flyway population of American black ducks (Anas rubripes). Understanding habitat selection and activities of waterfowl during the non-breeding period is important for directed habitat management on national wildlife refuges and in other wetlands important in meeting regional waterfowl conservation objectives. During November–February 2011–2013, we investigated diurnal habitat selection and activities of dabbling ducks (Anatini) among 5 common wetland types relative to emergent cover, water depth, and energetic carrying capacity (i.e., duck energy days [DEDs]) in western Tennessee, USA. We observed waterfowl daily and sampled food resources monthly at Tennessee and Cross Creeks National Wildlife Refuges. Mallard (Anas platyrhynchos), gadwall (A. strepera), northern pintail (A. acuta), and American green-winged teal (A. carolinensis) selected moist-soil wetlands over wooded, aquatic bed, and open water wetland types. Gadwall also selected deeper wetlands containing submersed aquatic vegetation. Foraging was the dominant activity of all dabbling ducks in mudflats and moist-soil wetlands, and it was also dominant in wooded wetlands for green-winged teal and gadwall. Deep, open water was avoided by dabbling ducks. Selection of wetland types was negatively correlated with increasing water depth and positively correlated with increasing emergent cover and DEDs. Shallowly flooded moist-soil and wooded wetlands provide high-energy foods and dense emergent cover, and are important to a diversity of dabbling ducks during winter. © 2017 The Wildlife Society.

The flood pulse drives primary productivity, biotic communities, and abiotic processes in large river systems; however, the effects of floods on restored floodplain lakes and associated wetlands are poorly understood. Record flooding of the Illinois River, Illinois, in 2013 reconnected two floodplain preserves under restoration that had been disconnected from the river by levees for >80 years. Differences in hydrological connections between sites created a natural experiment where field-based data collection could be employed to document flood effects. Levee failure and subsequent river connection at Merwin Preserve increased nutrient capture and floodwater retention, shifted microbial and invertebrate communities, increased fish species richness, spawning and nursery habitat, and stimulated production of moist-soil plant communities during summer drawdown that provided foraging habitat for spring-migrating waterfowl. However, increased hydrologic connectivity during the growing season resulted in loss of submersed vegetation and habitat for autumn-migrating waterfowl. In contrast, river water overtopped the levee at Emiquon Preserve during a 6-day event that resulted in marginal changes in the bacterial community and negligible changes in water quality and community diversity. Tradeoffs among ecological services should be carefully considered when reconnection of highly altered rivers to restored lakes and wetlands is proposed.

Aerial surveys are a valuable tool for monitoring wildlife and their habitats throughout North America, but manned aerial surveys for monitoring aquatic vegetation communities have seldom been evaluated rigorously. We used a fixed-wing aircraft and modified double observer method to survey an invasive aquatic macrophyte, water hyacinth (Eichhornia crassipes), and other floating-leaved aquatic vegetation along Illinois River to evaluate detection probability and error associated with size, extent, and species identification during aerial surveys. Generally, error rates for species identification (range = −3.7% − 1.0% mean error) and extent ( $$ \overset{-}{\boldsymbol{x}} $$ = 2.2 ± 2.2% error) were low, but aerial estimates of bed size ( $$ \overset{-}{\boldsymbol{x}} $$ = −0.65 ± 0.17 ha mean error) were less accurate. Aerial surveys were rapid ( 0.04 ha. However, size estimates were much less accurate when beds were 0.04 ha) beds and tracking occurrence of individual species of floating-leaved aquatic vegetation.

The interaction of animals with their food can yield insights into habitat characteristics, such as perceived predation risk and relative quality. We deployed experimental foraging patches in wetlands used by migrating dabbling ducks (Anas spp.) in the central Illinois River Valley to estimate variation in seed removal and giving-up density (GUD; i.e., density of food remaining in patches following abandonment) with respect to seed density, seed size, seed depth in the substrate, substrate firmness, perceived predation risk, and an energetic profitability threshold (i.e., critical food density). Seed depth and the density of naturally-occurring seeds outside of experimental plots affected seed removal and GUD in experimental patches more than perceived predation risk, seed density, seed size, or substrate firmness. The greatest seed removal and lowest GUDs in experimental patches occurred when food resources in alternative foraging locations outside of plots (i.e., opportunity costs) appeared to be near or below a critical food density (i.e., 119–181 kg/ha). Giving-up densities varied substantially from a critical food density across a range of food densities in alternative foraging locations suggesting that fixed GUDs should not be used as surrogates for critical food densities in energetic carrying capacity models. Foraging and resting rates in and near experimental foraging patches did not reflect patterns of seed removal and were poor predictors of GUD and foraging habitat quality. Our results demonstrated the usefulness of GUDs as indicators of habitat quality for subsurface, benthic foragers relative to other available foraging patches and suggested that food may be limited for dabbling ducks during spring migration in some years in the Midwest. This article is protected by copyright. All rights reserved.

Rapid assessment of food production and subsequent availability is fundamental to evaluating wetland management practices and general habitat quality for waterfowl. Traditional methods of estimating food biomass (e.g., plot and core sampling) require considerable time, expertise, and cost. Rapid assessment models using plant measurements or scanned seed-head area have recently been adapted to predict seed production in moist-soil wetlands. We evaluated existing models of seed production and estimated benthic seed density with data collected during autumn 2011 in western Tennessee, USA, to improve prediction capability of seed availability for waterfowl. Generally, all models explained significant variation (r2 = 0.85–0.98) and accurately predicted seed production in moist-soil plants (r2 = 0.84–0.97). Belowground proportions of seed biomass and duck energy days differed across species relative to previously reported biomass estimates in moist-soil wetlands (x¯ = 0.4–9.1%); thus, production estimates from models should be adjusted on a species-specific basis and the effect of belowground seeds on overall energetic carrying capacity estimates will vary with species composition of wetlands. We recommend use of updated most-soil rapid-assessment models incorporating seed bank estimates to predict waterfowl food availability and evaluate management practices. © 2017 The Wildlife Society.

Marsh birds (rallids, bitterns, and grebes) depend on emergent wetlands, and habitat loss and degradation are the primary suspected causes for population declines among many marsh bird species. We evaluated the effect of natural wetland characteristics, wetland management practices, and surrounding landscape characteristics on marsh bird occupancy in Illinois during late spring and early summer 2015-2017. We conducted call-back surveys following the North American Standardized Marsh Bird Survey Protocol three times annually at all sites (2015 n = 49, 2016 n = 57, 2017 n = 55). Across all species and groups, detection probability declined 7.1% ± 2.1 each week during the marsh bird survey period. Wetlands managed for waterfowl (ducks, geese, and swans) had greater occupancy than reference wetlands. Marsh bird occupancy increased with greater wetland complexity, intermediate levels of waterfowl management intensity, greater proportions of surface water inundation, and greater proportions of persistent emergent vegetation cover. Wetland management practices that retain surface water during the growing season, encourage perennial emergent plants (e.g., Typha sp.), and increase wetland complexity could be used to provide habitat suitable for waterfowl and marsh birds.

Stopover sites provide crucial habitat for waterfowl to rest and refuel during migration. Knowledge of which land-cover types are of greatest importance to migrating waterfowl and how the surrounding landscape influences their use can inform management decisions and conservation plans to adequately meet resource requirements. Specifically, spring migration habitat is essential for waterfowl preparing for breeding yet is an understudied period of the life cycle. We placed radio-transmitters on Mallards (Anas platyrhynchos) and Green-winged Teal (Anas crecca) between January and April 2016–2017 in the Wabash River Valley of Illinois and Indiana to assess habitat use and movement patterns. Both Mallards and Green-winged Teal primarily used emergent and woody wetlands, with 89% of use points in these land-cover types even though they made up

Despite extensive anthropogenic degradation of most wetlands and other aquatic habitats associated with large rivers in the Midwest, the region still supports continentally important numbers of waterbirds during autumn and spring migration; however, few data exist to evaluate wetland restoration success and identify thresholds where changes in management may be necessary to meet conservation targets. We tracked waterbird response to restoration of a historical floodplain wetland complex along the Illinois River during 2007–2013 relative to waterbird use of other wetlands and floodplain lakes in the region. Dabbling ducks and other waterbirds showed dramatic responses to restoration, each accumulating more than 3 million use-days/year and comprising more than 30% of the total waterbird use-days in the Illinois River Valley during autumn and spring migrations. We identified use that was strongly disproportionate to availability within the region for several waterbird taxa and documented nesting by several species of conservation concern. Many species and foraging guilds of waterbirds [e.g., American coot (Fulica americana), dabbling ducks (Anatini)] responded rapidly to wetland restoration, continued to use Emiquon Preserve regardless of changing conditions at reference sites, and showed relatively limited temporal variation, thereby demonstrating their utility as indicators of habitat conditions and restoration trajectory.

More than half of the natural wetlands in the Illinois River valley (IRV) have been lost through conversion of floodplain wetlands and lakes to drainage and levee districts for agricultural production. During 2007–2013, we monitored the response of wetland vegetation communities to restoration at Emiquon Preserve, a former floodplain that was drained and farmed for more than 80 years. Spatial coverage of wetland vegetation and other cover types rapidly expanded from 252 ha in 2007 to 1,944 ha in 2013 (mean 1,512 ± 239 ha) with little supplemental planting or hydrological management. Restored vegetation emulated aquatic plant communities that were largely eliminated from the IRV, most importantly floating-leaved and submersed aquatic vegetation. Mean annual wetland cover included aquatic bed (44%), open water (20%), persistent emergent vegetation (10%), hemi-marsh (10%), and nonpersistent emergent vegetation (9%). Average moist-soil seed and tuber density was similar to managed wetlands in the IRV (mean 724 ± 224 kg/ha). A viable option for restoration of diverse aquatic macrophyte communities within degraded wetlands of large river systems includes passive restoration of hydrology and vegetation behind levees while maintaining infrastructure to facilitate drawdowns when necessary or to mimic historical conditions.

Scientists estimate biomass of invertebrates to evaluate wetland management practices, estimate energetic carrying capacity for wildlife, assess habitat condition and disturbance, and quantify ecosystem services. For waterfowl and other waterbirds in North America, carrying capacity in migratory and wintering regions is estimated using food density, of which invertebrates can be a significant component. However, we are not aware of previous literature that has described the effects of reagents used during core sample processing on invertebrate biomass and abundance. We tested the effects of hydrogen peroxide on aquatic invertebrates to determine whether a reagent used to disassociate soils during core sample processing biased estimates of biomass and abundance. Wet masses of chironomid larvae were less (x̄ = 23.5% loss) in samples exposed to hydrogen peroxide than those exposed only to tap water and biomass decreased approximately 2.9% with each minute of exposure time. Dry mass of larvae was less in samples exposed to hydrogen peroxide than in those exposed only to tap water (x̄ = 2.5% loss), but we did not detect an effect of exposure time on mass lost. Hydrogen peroxide did not influence the abundance of macro- or microinvertebrates in test samples. Thus, bias associated with dry mass estimates of invertebrates from core samples treated with hydrogen peroxide is likely minimal in terms of application in energetic carrying capacity models. However, use of hydrogen peroxide during core sample processing may cause significant bias if biomass estimates are based on wet mass.

The Nature Conservancy’s wetland restoration at the Emiquon Preserve has been a success to date, but there are warning signs of undesirable change if left unmanaged. A water control structure built in 2016 will increase management capabilities, but periodic connection to the river, which has experienced human alterations typical of rivers in eastern North America and Europe, also introduces risks. The Conservancy’s planning process has identified (1) management targets (e.g., diverse native fish populations); (2) Key Ecological Attributes (KEAs) that maintain the targets (e.g., relatively deep over-wintering habitats for fishes); (3) measurable indicators for the KEAs (e.g., depth in winter); and (4) desirable ranges for the indicators (e.g., 10% of the aquatic area has depths of 2–3 m and dissolved oxygen levels of 4–6 mg/l). Assessments and experiments completed to date have focused on documenting the restoration, evaluating effects of the record flood of 2013, and predicting outcomes of management actions. Simulation models of hydrology, hydraulics, and vegetation response developed during the planning process allayed some concerns of stakeholders, but not all outcomes are predictable from either current theory or management experience. Therefore, each action can be considered not only as an adaptive management experiment focused on sustaining targets, but also contributing to ecological theory and restoration practice on a broader scale.

Wetland restoration in highly modified landscapes involves balancing target ecosystem functions and values with constraints of landscape and stakeholder context. Often, a restored wetland complex cannot meet all target conditions simultaneously, and tradeoffs must be understood, evaluated, and quantified. We examined the tradeoff between providing migratory bird sanctuary and increasing public recreational opportunities within a restored floodplain wetland complex along the Illinois River. We surveyed the distribution and behavior of waterbirds in response to a gradient of spatial and temporal disturbances from waterbird hunting activities. Using ArcMap and spatial interpolation of waterbird densities as a novel approach to quantify sanctuary area, we estimated that approximately 42% of Emiquon Preserve functioned as sanctuary across disturbance intensities, hunter distribution, and time periods during autumn migration. Waterbird abundance did not increase with short-term temporal sanctuary or decreased hunting intensity. Disturbance distance around hunting locations was 752.1 m, overall, and increased 38.4 m for each additional hunting party. Exclusion distance around hunting locations was greater in areas with greater mean disturbance frequency. We question the effectiveness of short-term temporal sanctuary for waterbirds at the expense of recreational opportunities and advocate our analytical approach to quantify sanctuary area and disturbance buffers without experimentally causing disturbances.

The adaptation of birds to urban environments has created direct hazards to air transportation with the potential for catastrophic incidents. Bird–aircraft collisions involving Canada geese (Branta canadensis; goose) pose greater risks to aircraft than many bird species due to their size and flocking behavior. However, information on factors driving movements of geese near airports and within aircraft arrival/departure areas for application to management are limited. To address this need, we deployed 31 neck collar-mounted global positioning system transmitters on Canada geese near Midway International Airport in Chicago, Illinois, USA during November 2015 to February 2016. We used the movement data obtained to model environmental and behavioral factors influencing the intersection of goose movements (i.e., transition from 1 location to another) with air operations areas (i.e., aircraft flight paths). Of 3,008 goose movements recorded, 821 intersected a 3-km buffer around the airport representing U.S. Federal Aviation Administration recommended distances from wildlife attractants, and 399 intersected flight paths for approaching and landing aircraft. The effects of weather (i.e., snow cover, temperature, wind speed) on the probability of geese flying varied with different air operation areas while certain habitat resources greatly increased the probability of intersection. For example, the juxtaposition of foraging (railyards with spilled grain) and loafing areas (rooftops) near the airport led to a higher probability of movements intersecting important air operations areas. The average altitude of flying geese was 29.8 m above the ground, resulting in the greatest risk of collision being within 0.5 km of the end of runways. We suggest airport goose collision mitigation management actions, such as reducing habitat resources near the airport and using focused nonlethal harassment or physical modifications, when guided by animal movement data, may further mitigate bird-strike risks.

In computer vision, significant advances have been made in recent years on object recognition and detection with the rapid development of deep learning, especially deep convolutional neural networks (CNN). The majority of deep learning methods for object detection have been developed for large objects and their performances on small-object detection are not very good. This paper contributes to research in low-resolution small-object detection by evaluating the performances of leading deep learning methods for object detection using a common dataset, which is a new dataset for bird detection, called Little Birds in Aerial Imagery (LBAI), created from real-life aerial imagery data. LBAI contains birds with sizes ranging from 10px to 40px. In our experiments, some of the best deep learning architectures were implemented and applied to LBAI, which include object detection techniques such as YOLOv2, SSH, and Tiny Face, in addition to small instance segmentation techniques including U-Net and Mask R-CNN. Among the object detection methods, experimental results demonstrated that SSH performed the best for easy cases, whereas Tiny Face performed the best for hard cases, i.e. where a cluttered background makes detecting birds difficult. Among small instance segmentation methods, experimental results revealed U-Net achieved slightly better performance than Mask R-CNN.

Thousands of lesser scaup (Aythya affinis) die during spring and fall migrations through the upper Midwest, USA, from infections with Cyathocotyle bushiensis and Sphaeridiotrema spp. (Class: Trematoda) after ingesting infected intermediate hosts, such as non-native faucet snails (Bithynia tentaculata). The lesser scaup is a species of conservation concern and is highly susceptible to these infections. We collected female lesser scaup from spring migratory stopover locations throughout Illinois and Wisconsin and assessed biochemical and morphological indicators of health in relation to intestinal helminth loads. Helminth species diversity, total trematode abundance, and the infection intensities of the trematodes C. bushiensis and Sphaeridiotrema spp. were associated with percent body fat, blood metabolites, hematological measures, and an index of foraging habitat quality. Helminth diversity was negatively associated with percent body fat, albumin concentrations, and monocytes, whereas glucose concentrations displayed a slight, positive association. Total trematode abundance was negatively associated with blood concentrations of non-esterified fatty acids and albumin. Infections of C. bushiensis were positively related to basophil levels, whereas Sphaeridiotrema spp. infection intensity was negatively associated with packed cell volume and foraging habitat quality. Thus, commonly measured health metrics may indicate intestinal parasite infections and help waterfowl managers understand overall habitat quality. Intestinal parasitic loads offer another plausible mechanism underlying the spring condition hypothesis.

Estimates of time spent at migratory stopovers are often used to develop habitat conservation objectives for a variety of avian species, namely waterfowl. Because of limited previous research and a need for accurate conservation planning objectives, we estimated stopover duration and factors influencing stay of mallards (Anas platyrhynchos) in Illinois using radio telemetry during autumns 2009 and 2010. Total stopover duration of migrating mallards was approximately 68 days and was approximately twice that of previous studies which could have significant implications on habitat needs used for conservation planning purposes. Duration of stay post-capture did not vary by sex, body condition, year, or age but was inversely related to capture date. Our results suggest that wetland conservation objectives could increase 16.2% if our contemporary estimates were included in current planning models of the Upper Mississippi River and Great Lakes Region Joint Venture. 2014 The Wildlife Society.

We examined the associations between intestinal helminth infracommunity structure and infection parameters and the age, size, and year and region of collection of 130 female lesser scaup (Aythya affinis) during their 2014–2015 spring migrations through the upper Midwest, USA. We identified a total of 647,174 individual helminths from 40 taxa, including 20 trematodes, 14 cestodes, 4 nematodes and 2 acanthocephalans parasitizing lesser scaup within the study area. Lesser scaup were each infected with 2–23 helminth taxa. One digenean,Plenosoma minimum, is reported for the first time in lesser scaup and in the Midwest. Mean trematode abundance and total helminth abundance was significantly less in 2015 than 2014, and we suspect that colder weather late in 2015 impacted the intermediate host fauna and caused the observed differences. Brillouin's species diversity of helminths was greatest in the northernmost region of the study area, which coincides with the range of a non-indigenous snail that indirectly causes annual mortality events of lesser scaup. While host age and size were not determined to be influential factors of helminth infracommunity structure, non-parametric ordination and permutational analysis of co-variance revealed that year and region of collection explained differences in helminth infracommunities. Our results suggest that spatiotemporal variations play an important role in the structure of intestinal helminth infracommunities found in migrating lesser scaup hosts, and may therefore impact host ability to build endogenous reserves at certain stopover locations in the Midwest.

Managed 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 ( = 750.7 kg/ha) and mowed ( = 709.7 kg/ha) than disked plots ( = 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

Scientists, 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.

Even though avian damage to sunflower (Helianthus annuus L.) is a worldwide economic issue, several of the current methods used to reduce sunflower damage were developed and tested in the Prairie Pothole Region of the United States. An intensive research program was conducted in that area because of the regionalized concentration of sunflower production and the severe incidences of blackbird (Icteridae) depredation. During the past 40 years, federal and university scientists tested chemical and physical frightening agents, aversive repellents, bird-resistant sunflowers, decoy crops, habitat management, population management, and cultural modifications in cropping. Some of these techniques have broad applicability and may be useful in depredation scenarios involving other bird species and crops. Population suppression is intuitively appealing, but it typically fails beyond local scales because of avian mobility, population dynamics, and public antipathy. Scare devices, repellents, habitat management, and decoy crops are more likely to meet the test of predictable efficacy and practicality.