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Abstract Wildlife species confront threats from climate and land use change, exacerbating the influence of extreme climatic events on populations and biodiversity. Migratory waterbirds are especially vulnerable to hydrological drought via reduced availability of surface water habitats. We assessed how whooping cranes (Grus americana) modified habitat use and migration strategies during drought to evaluate their resilience to changing conditions and adaptive capacity. We categorized >8000 night‐roost sites used by 146 cranes from 2010 to 2022 and examined relative use during non‐drought, moderate drought, and extreme drought conditions. We found cultivated and uncultivated palustrine and lacustrine wetlands were generally used less during droughts than non‐drought conditions. Conversely, impounded palustrine and lacustrine systems and rivers served more frequently as drought refugia (i.e., used more during drought than non‐drought conditions). Night roosts occurred primarily on private lands (86% overall); public land use decreased with latitude and increased with drought severity, with greatest use (56%) occurring during severe autumn drought in the southern Great Plains. Quantifying use of identified critical habitats in the United States indicated that Cheyenne Bottoms State Waterfowl Management Area and Quivira National Wildlife Refuge were used less during drought, and the Central Platte River and Salt Plains National Wildlife Refuge received similar use during drought compared to non‐drought conditions. Our findings provide insights into compensatory use of habitats, where impounded surface water may function in a complementary fashion with natural wetlands. Collectively, these and other types of wetlands distributed across the migration corridor provided a reliable network of habitat available across the Great Plains. A diversity of wetlands available during variable environmental conditions would be useful in supporting continued recovery of whooping cranes and likely have benefits for a wide array of migratory birds.

Abstract Natal dispersal is a key demographic process for evaluating the population rate of change, especially for long‐lived, highly mobile species. This process is largely unknown for reintroduced populations of endangered avian species. We evaluated natal dispersal distances (NDD) for male and female Whooping Cranes (Grus americana) introduced into two locations in central Wisconsin (Necedah National Wildlife Refuge, or NNWR, and the Eastern Rectangle, or ER) using a series of demographic, spatial, and life history‐related covariates. Data were analyzed using gamma regression models with a log‐link function and compared using Akaike information criterion corrected for small sample sizes (AICc). Whooping Cranes released in the ER dispersed 261% further than those released into NNWR, dispersal distance increased 4% for each additional nesting pair, decreased about 24% for males as compared to females, increased by 21% for inexperienced pairs, and decreased by 3% for each additional year of age. Natal philopatry, habitat availability or suitability, and competition for breeding territories may be influencing observed patterns of NDD. Whooping Cranes released in the ER may exhibit longer NDD due to fragmented habitat or conspecific attraction to established breeding pairs at NNWR. Additionally, sex‐biased dispersal may be increasing in this population as there are more individuals from different natal sites forming breeding pairs. As the population grows and continues to disperse, the drivers of NDD patterns may change based on individual or population behavior.

Bison (Bison spp) are being reintroduced into semi-wild, spatially constrained herds across North America and Europe. Herd managers are concerned about gastrointestinal (GI) nematode parasites as they care for the health of their bison. We examine how demographics, grazing location, herd management, and anthelmintic treatments affect the fecal egg counts (FECs) of GI nematodes within a reintroduced Plains bison (Bison bison bison) herd in the Great Plains. Our results suggest that younger bison ( 6 yrs of age). FECs of both Trichuris spp. and particularly Nematodirus spp. were much more abundant, relatively, during the first year of a bison's life. This pattern was also true of Moniezia spp. and Eimeria spp., however, strongyle-type spp. FECs appeared to peak in relative abundance during the second year of life. Our data also indicate that FECs are influenced by differences in land-use histories of pastures previously grazed by cattle or by the proportion of frequent flooding in different pastures. Treatment results suggest that fenbendazole may more effective than moxidectin at lowering FECs of bison over the long-term, and lasting effects of at least one administered anthelmintic treatment. Multiplex PCR assays revealed that American bison share GI nematodes with cattle including: Ostertagia spp., Haemonchus placei, Cooperia onchophora, and Oesophagostomum spp, but did not detect the presence Trichostrongylus columbriformis. Our results may have wider conservation implications for reintroduction efforts of American bison, as well as the endangered European bison (Bison bonasus).

Abstract Wet meadows are a declining and increasingly degraded ecosystem type. They contribute numerous ecosystem services, including nutrient cycling, water storage, and filtration, and provision of wildlife habitat, particularly for wetland‐dependent species such as the Whooping Crane (Grus americana). Conservation and restoration of wet meadows rely on understanding their hydrology but characterization of wet meadow hydroregimes is difficult given their hydrologic complexity, high variability, and distinct regional differences. To address this challenge, we used ground‐based time‐lapse imagery to assess inundation dynamics of an archetypal wet meadow over a six‐year period in the Central Platte River Valley, Nebraska, USA. We analyzed over 6500 images from March 2011 to May 2017 in the open‐source java‐based image processing software ImageJ. We also obtained data on groundwater, streamflow, precipitation, and evapotranspiration. We assessed the relationship between wet meadow inundation and hydrologic variables using wavelet coherence to look at fluctuations across a time–frequency spectrum and used random forest to identify seasonally specific variables of importance. We found hydroperiod, the duration surface water ponded within the wet meadow, had a mean of 141 d, on average lasting from 10 December to 1 May, but varied annually. Inundation generally peaked in the early spring, on average 10 March, but demonstrated a bimodal distribution, peaking again in late spring during wetter years. While inundation responded rapidly to precipitation events, it was highly related to streamflow, while an elevated groundwater table was necessary for sustained inundation. Overall, our study provided a comprehensive hydrological characterization of a reference wet meadow and demonstrated the utility of time‐lapse cameras for high‐resolution monitoring and assessment of highly variable wetland systems. Considering the uncertainties surrounding land‐ and water‐use changes, climate change, and the increasing demand for freshwater resources by growing human communities, understanding functional wet meadow hydroregimes and interrelated drivers is essential to inform wet meadow restoration, conservation, and management efforts.

Collisions with anthropogenic structures by long-distance migrants and threatened and endangered species are a growing global conservation concern. Increasing the visibility of these structures may reduce collisions but may only be accepted by local residents if it does not create a visual disturbance. Recent research has shown the potential for ultraviolet (UV) light, which is nearly imperceptible to humans, to mitigate avian collisions with anthropogenic structures. We tested the effectiveness of two UV (390–400 nm) Avian Collision Avoidance Systems (ACASs) at reducing collisions at two 260-m spans of marked power lines at the Iain Nicolson Audubon Center at Rowe Sanctuary, an important migratory bird stopover location in Nebraska. We used a randomized design and a tiered model selection approach employing generalized linear models and the Akaike Information Criterion to assess the effectiveness of ACASs considering environmental (e.g., precipitation) and detection probability (e.g., migration chronology) variables. We found focal (assessed power line) and distal (neighboring power line) ACAS status and environmental variables were important predictors of avian collisions. Our top model suggests that the focal ACAS illumination reduced collisions by 88%, collisions were more likely at moderate (10–16 km/h) compared to lower or higher wind speeds, and collision frequency decreased with precipitation occurrence. Our top model also indicates that the distal ACAS illumination reduced collisions by 39.4% at the focal power line when that ACAS was off, suggesting a positive “neighbor effect” of power line illumination. Although future applications of ACASs would benefit from additional study to check for potential negative effects (for example, collisions involving nocturnal foragers such as bats or caprimulgiform birds drawn to insects), we suggest that illuminating power lines, guy wires, towers, wind turbines, and other anthropogenic structures with UV illumination will likely lower collision risks for birds while increasing human acceptance of mitigation measures in urban areas.

A portion of the Aransas-Wood Buffalo population of Whooping Cranes (Grus americana) stopover within the Central Platte River Valley (CPRV) annually. Past studies have found Whooping Cranes select herbaceous wetlands over agricultural fields when evaluated at a migration-corridor scale. However, recent studies conducted within the CPRV have reported Whooping Cranes selected agricultural fields and avoided herbaceous landcover classes. We hypothesized that much of this discrepancy was due to differences in landcover classifications used in previous studies, particularly those related to wetland designations. We used multiple existing, fine-scale geospatial data sources considering both landcover and hydrological factors to define unique and regionally specific ecotopes, which are the smallest homogenous and biologically relevant mappable units of analysis in landscape ecology (e.g., meadow-marsh, upland agriculture, etc.). We examined whether ecotope-based landcover, when evaluated at multiple spatial scales (i.e., 400 m and 1000 m), predicted terrestrial Whooping Crane occurrence within the CPRV. We used generalized linear mixed models within an information-theoretic approach to assess Whooping Crane occurrence within the CPRV. We found distinct ecotopes at the 1000-m scale explained nearly 40% of the variation in Whooping Crane occurrence. Ecotope models outperformed models including only their component parts such as flooding frequency and wetland designation. Whooping Cranes occurred more frequently within wetland portions of both agricultural fields and natural herbaceous communities and were less likely to use analogous upland components. We also found that occurrence was positively associated with proximity to the main channel of the Platte River and that Whooping Cranes avoided roads and developed areas, as several other studies have reported. Our findings indicate herbaceous and agricultural wetland areas should be targeted for Whooping Crane conservation efforts within the CPRV and perhaps regionally.

Although anuran reproductive behavior follows a phenological pattern, environmental factors may influence the timing of anuran activity. To characterize the spring calling phenology of Pseudacris maculata (boreal chorus frog) we installed acoustic recorders during three spring breeding seasons (2015–2017) within wet meadow and forested slough habitats in central Nebraska near the Platte River. The recorders were paired with time-lapse camera systems that were used to measure vegetation change and wet meadow inundation. We examined the relationship between environmental variables, including temperature, precipitation, and hydropattern, and P. maculata calling activity using random forest models. Calling activity exhibited diel and seasonal variation with differences observed between habitats. Hourly call activity was highest between 20:00 and 01:00, with diurnal and sometimes near-continuous calling observed at the wet meadow but not at the forested slough. Random forest models explained 73% of calling activity variance at the wet meadow and 45% at the forested slough, suggesting additional factors, such as predation, may be influential at the forested slough, as it exhibited near permanent hydrology. P. maculata was predicted to increase chorusing at the 70th day of the year at the wet meadow but not until the 100th at the forested slough. When average air temperatures exceeded 5 °C, calling activity was predicted to increase at both wetlands, and calling declined below this temperature. Hydropattern and weekly precipitation accumulation were important predictors of P. maculata calling activity. Our findings highlight the importance of climatic factors such as temperature and precipitation regimes, in addition to habitat conditions such as water-availability, on P. maculata calling activity. Furthermore, this study demonstrates the utility of multimodal passive monitoring technologies, including both visual and auditory tools, for understanding the environmental factors that influence biological activity. Multimodal approaches can be especially useful for documenting and measuring vocal-taxa diversity, activity, and drivers of change.

Data were collected using multimodal monitoring technologies pairing sound recorders with time-lapse camera systems. In the spring of 2015, 2016, and 2017, sound recordings and imagery were collected at a wet meadow and forested slough in the Central Platte River Valley of Nebraska. Boreal chorus frog (Pseudacris maculata) calling activity was obtained from analysing sound recordings. Habitat metrics including vegetation phenology and wet meadow hydropattern were derived from image analysis. This dataset can be used to assess phenology, anuran vocalization activity, and environmental change, as well as to further understanding of wetland ecology. Data are co-submitted with manuscript Brinley Buckley, E. M., Gottesman, B. L., Caven, A. J., Harner, M. J., and Pijanowski, B. C., Assessing ecological and environmental influences on Boreal Chorus Frog (Pseudacris maculata) spring calling phenology using multimodal passive monitoring technologies. Ecological Indicators (In Press).

Recent detections of large gatherings of Whooping Cranes suggest that flock sizes may be increasing at some stopover locations during both the spring and fall migrations. We used the public sightings database managed by the US Fish and Wildlife Service from 1942 to 2018 to analyze data for long-term trends in group size. We then examined the spatial distribution of large groups to explore potential explanations for these occurrences. The proportion of Whooping Crane groups comprised of 2, 3, and 4–6 individuals showed no trend over time. However, observations of individuals showed a declining trend and groups of 7–9 and ≥10 showed an increasing trend. The frequency of groups observed exceeding 5 and 10 individuals were better predicted by survey year than by Whooping Crane population size suggesting that an increasing population is not the sole driver of large group occurrences. Our results indicate that large groups occur disproportionately within the 50% migration corridor, at staging areas within the first or last 20–30% of the migration path, and near conservation-managed wetlands, particularly within the southern Great Plains. Our results suggest that in addition to population growth, conspecific attraction, location within the migration corridor, and habitat loss may be contributing to large group occurrences. Further research is needed to determine the degree to which these factors influence large Whooping Crane group formation. The gathering of large numbers of Whooping Cranes in a single location presents potential tradeoffs for the species. While increasing group sizes may improve threat detection and avoidance, it comes at a cost of increased disease and mass mortality risk.

The 2016 discovery of Emerald Ash Borer (Agrilus planipennis; EAB) in Nebraska warranted an assessment of the physical conditions of ash trees (Fraxinus spp.) across the state. Here we present a dataset of current physical conditions and spatial location of 30 Green Ash (Fraxinus pennsylvanica) throughout riparian woodlands along the Platte River in southcentral Nebraska. Ten Green Ash were assessed along transect lines through three riparian woodlands. Physical indicators of EAB infection and morphometric characteristics were recorded at each tree including diameter at breast height (DBH), estimated age, canopy condition rating scale (CCRS), borer holes, woodpecker holes, serpentine gallery, epicormic shoots, basal shoots, and bark splitting to document the health and condition of local Green Ash. We recorded variables of crown class category (CCC), crown ratio, and Green Ash seedling and sapling numbers within 6 m of the measured tree to document current canopy cover and regenerative potential of Green Ash within each woodland. Metric summaries are provided looking at each woodland individually and at the woodlands combined. Keywords: Green Ash, Emerald Ash Borer, Riparian woodlands, Platte River

The datasets in this article are associated with the research article ‘Assessing biological and environmental effects of a total solar eclipse with passive multimodal technologies’ (Brinley Buckley et al., 2018). We documented biotic and abiotic changes during a total solar eclipse on 21 August 2017, in south-central Nebraska, USA, with a multimodal suite of tools, including time-lapse camera systems, data loggers, and sound recording devices. Time-lapse images were used to approximate changes in light, data loggers were used to record temperature and humidity, and sound recordings were used to calculate acoustic indices characterizing variation in the soundscape, as well as to manually identify and estimate avian vocalization activity.

Anthropogenic climate change and habitat loss pose major threats to grassland breeding birds, the most rapidly declining group of birds in continental North America. Although previous studies have investigated grassland breeding bird responses to land management, few empirical studies explore their responses to climatic variation or its interactions with land management, which warrant urgent conservation attention. We evaluated the effects of climate and land management parameters on an indicator species for grassland breeding birds, the Grasshopper Sparrow (Ammodramus savannarum), a Neotropical migrant of conservation concern whose global population has declined by more than two thirds since 1970. We quantified Grasshopper Sparrow responses to climate variation, land management actions, and their interactions in the Platte River Valley, Nebraska, in the North American Great Plains, using six years of mark-recapture data collected via the Monitoring Avian Productivity and Survivorship (MAPS) protocol. We implemented generalized linear mixed models to estimate avian population trends (adult abundance and productivity) in response to changes in precipitation and temperature as well as cattle grazing, haying, and prescribed burning. Our models showed that climatic variation, especially spring precipitation, was the most important driver of avian population trends. Grasshopper Sparrow abundance declined with increasing spring precipitation, but prescribed burns helped mitigate this effect and were positively related to productivity, especially during years of lower spring temperatures. Our findings demonstrate the vulnerability of grassland bird population trends to ongoing and predicted climate change as well as the potential of land management actions to mitigate some negative effects of climate change on grassland breeding birds.

Available stopover habitats with quality foraging opportunities are essential for migrating waterbirds, including Whooping Crane (Grus americana). Several studies have evaluated habitats used by Whooping Crane for roosting throughout its migration corridor; however, habitats associated with foraging and other diurnal activities have received less attention. We used data collected from 42 Whooping Crane individuals that included 2169 diurnal use locations within 395 stopover sites evaluated during spring 2013 to fall 2015 to assess diurnal habitat selection throughout the U.S. portion of the migration corridor. We found that Whooping Crane selected wetland land-cover types (i.e., open water, riverine, and semipermanent wetlands) and lowland grasslands for diurnal activities over all other land-cover types that we evaluated, including croplands. Whooping Crane generally avoided roads, and avoidance varied based on land-cover class. There has been considerable alteration and destruction of natural wetlands and rivers that serve as roosting and foraging sites for migrating Whooping Crane. Given recent droughts and the likelihood of future landscape changes within the migration corridor, directing conservation efforts toward protecting and enhancing wetland stopover areas may prove critical for continued growth of the last remaining wild population of Whooping Crane. Future studies of this Whooping Crane population should focus on specific wetland complexes and riverine sites throughout the migration corridor to identify precise management actions that could be taken to enhance and protect these imperilled land-cover types.

We investigate the scientific and communicative value of time-lapse imagery by exploring applications for data collection and visualization. Time-lapse imagery has a myriad of possible applications to study and depict ecosystems and can operate at unique temporal and spatial scales to bridge the gap between large-scale satellite imagery projects and observational field research. Time-lapse data sequences, linking time-lapse imagery with data visualization, have the ability to make data come alive for a wider audience by connecting abstract numbers to images that root data in time and place. Utilizing imagery from the Platte Basin Timelapse Project, water inundation and vegetation phenology metrics are quantified via image analysis and then paired with passive monitoring data, including streamflow and water chemistry. Dynamic and interactive time-lapse data sequences elucidate the visible and invisible ecological dynamics of a significantly altered yet internationally important river system in central Nebraska.

Aransas-Wood Buffalo population (AWBP) Whooping Cranes are increasingly using inland areas for a portion of the winter. There have been individuals near Granger Lake during five of the last 13 winters and 11 of the last 13 winters in Colorado and Wharton counties, Texas, USA. At least 11 individuals used Colorado/Wharton counties in 2022–2023, and 18 used this area in 2023–2024. We used data from all Whooping Cranes with active transmitters from 2009–2018 and from three additional inland wintering individuals from 2017–2022. We compared 95% auto-correlated kernel density estimates (AKDE) and daily distance movements for coastal wintering cranes and those that spent a portion of their winter inland. We also examined daily movement patterns in relation to wintering range use (inland or coastal) considering demographic and temporal factors with generalized linear mixed-effects models (GLMM). Six marked birds across 10 bird-winters from 2011–2021 spent between 3.1–99.3% of their winter at inland areas. Inland wintering birds had AKDE home ranges that were 3.1 times as large as coastal wintering birds. Additionally, the top GLMM predicted that spending a portion of the winter at inland areas equated to a 92.0±4.2% increase in daily movement during the winter. We found that several other factors influenced daily movement patterns, which warrant consideration when comparing between the groups. Age and family status impacted the model, but subadults, family groups, and adults without juveniles all had overlapping confidence intervals. Daily movements followed a quadratic temporal pattern, with greater movements in the late fall and early spring. Continued use of inland areas has implications for how we manage, monitor, and plan for this population’s recovery.