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Several researchers have tried to find relationships between acoustic indices and vocal animal communities to use acoustic indices as a passive monitoring method, as human-derived surveys are expensive, time-consuming, and suffer from observer bias. However, supplanting manual surveys with acoustic indices is a daunting task, considering effective indices for biological monitoring need to differentiate biologically relevant sounds from the broader soundscape, including anthropophony and geophony. The objective of our study was to test how well acoustic indices can be applied to avian community monitoring within a temperate grassland ecosystem in North America. We collected avian community data and calculated six commonly used acoustic indices from recordings in an intact lowland tallgrass prairie in the Central Platte River Valley of Nebraska throughout the avian breeding seasons of 2019–2021. Singular acoustic indices had only weak correlations with all community metrics. However, multivariate models including multiple acoustic indices showed potential for monitoring grassland bird abundance when anthropophony was considered. Fragmented grassland remnants likely experience significant anthropophony that needs to be accounted for when monitoring avian populations. Additionally, multivariate models incorporating several indices may provide a more accurate prediction of avian biophony than individual acoustic indices.

Granivorous rodents are important components of ecosystems not only because they consume seeds but also because some aid in seed dispersal through seed‐caching behaviors. Some rodents bury seeds in shallow pits throughout territories, called scatterhoards, that individuals recover, pilfer, or transfer to other caches. We suspect some single‐seed caches in environments represent missed seeds from reclaiming or pilfering caches. We documented the sloppiness of seed removal from scatterhoards of soapweed yucca (Yucca glauca) seeds by Ord's kangaroo rats (Dipodomys ordii). We quantified the frequency and location of seeds remaining. In an experiment with artificial caches of three sizes, kangaroo rats harvested 51% of caches after one night, and 53% had incomplete recovery with at least one seed remaining. The greater the number of seeds in caches, the greater frequency of incomplete recovery. In another experiment with natural and artificial caches, 75% of caches were excavated after 8 days, with at least 70% having at least one seed remaining. Regardless of original cache size, a single seed represented the mode for seeds remaining. Incomplete recovery of seeds likely benefits plant establishment, potentially significantly in some systems. Remaining seeds, especially those buried at bottoms of caches, likely will stay undetected in landscapes, yielding propagules for subsequent plant generations. Soapweed yucca has large but light, flat wind‐dispersed seeds, and removal of caches with smaller seeds might have greater frequency of missed seeds during recovery and pilfering by rodents. Our results suggest that scatter‐hoarding granivores also contribute to plant establishment by leaving limited numbers of seeds behind when removing caches, at least in some systems. We documented the sloppiness of seed removal from scatterhoards of soapweed yucca (Yucca glauca) seeds by Ord's kangaroo rats (Dipodomys ordii). In two different experiments, we observed that >50% of caches removed or pilfered by kangaroo rats in the Sandhill Region of Nebraska had at least one seed remaining, with about 30% leaving limited seeds at the bottom of caches. Remaining seeds, especially those buried at bottoms of caches, likely will stay undetected in landscapes, yielding propagules for subsequent plant generations.

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.

Nuclear magnetic resonance (NMR) spectroscopy has evolved into a powerful tool for fragment-based drug discovery over the last two decades. While NMR has been traditionally used to elucidate the three-dimensional structures and dynamics of biomacromolecules and their interactions, it can also be a very valuable tool for the reliable identification of small molecules that bind to proteins and for hit-to-lead optimization. Here, we describe the use of NMR spectroscopy as a method for fragment-based drug discovery and how to most effectively utilize this approach for discovering novel therapeutics based on our experience.

Most vascular plants form symbioses with mycorrhizal fungi that associate with roots and provide nutrients to hosts in exchange for carbohydrates, as well as serve a range of other functions. Mycorrhizal fungi have been studied extensively in upland ecosystems, but we know less about their ecology at aquatic-terrestrial interfaces, especially their distributions at depth. Our objectives were to determine whether abundances of arbuscular mycorrhizal fungi (AMF) change as floodplain islands develop and to describe vertical distributions of AMF from the forest floor to the water table along the freely flowing Tagliamento River in northeastern Italy. We sampled surface sediments (0–10 cm) from three stages of island development on the floodplain—fresh deposits, pioneer islands, and established islands. We also sampled sediments vertically (0–150 cm) from the ground surface to the water table on an established island. We characterized abundance of AMF propagules (colonized roots, spores, and hyphae) within sediments. Roots available to host fungi were absent on fresh deposits; however, some viable spores and hyphae were available at these sites. Pioneer and established islands each had similar hyphal lengths (~860 cm cm −3 ) and colonized root lengths (~3 cm cm −3 ). Abundance of spores increased from depositional (3.5 ± 0.9 (±SE) cm −3 ) to pioneer (17 ± 6.1 cm −3 ) to established (32 ± 6.3 cm −3 ) islands. On an established island, AMF propagules were present at all depths sampled, including at the water table, providing first documentation of these symbionts to such depths in a riparian setting. Mycorrhizal fungi likely link aquatic and terrestrial habitats by connecting plants, soil, and ground water and may influence nutrient transfers among these subsystems.

Muskrats (Ondatra zibethicus) are semiaquatic rodents native to North American wetlands, including marshes, ponds, and slow-moving streams. In water, muskrats commonly build houses and feeding platforms with herbaceous vegetation and mud. These island structures benefit other species, but few studies have examined the roles these structures play for a community of wetland vertebrates. We studied the diversity, frequency of occurrence, and behaviors of vertebrates on muskrat structures in the Sandhill Region of Nebraska. From camera traps, we recorded over 37,700 observations of vertebrates, representing 57 species, including amphibians, mammals, raptors, reptiles, songbirds, and waterfowl. Vertebrate behaviors on structures included basking, copulating, displaying, foraging, grooming, perching, preening, raising young, resting, and vocalizing. In the Nebraska Sandhills, muskrats created island habitats beneficial to both migratory and local species, with structures appearing of particular importance to life history functions of many waterfowl and turtles. Muskrats represent ecosystem engineers, as their structures were the only natural islands in wetlands due to the general lack of trees and rocks in the region. We frequently observed the use of structures by multiple species simultaneously, further suggesting that island structures are limited in Sandhill wetlands. Our study highlights the great number of vertebrates that use muskrat structures for a host of life history and ecological functions. Throughout the distribution of muskrats, many other species likely use and rely on these island structures, as muskrats are an integral component of many wetland ecosystems in North America. Understanding the functionality and frequency of use for these structures by other wildlife is essential when managing populations of muskrats and the wetlands these mammals inhabit. La rata almizclera (Ondatra zibethicus) es un roedor semiacuático nativo de los humedales de Norteamérica, incluidos pantanos, estanques y arroyos de corriente lenta. En el agua, las ratas almizcleras suelen construir nidos y plataformas de alimentación con vegetación herbácea y barro. Estas estructuras insulares benefician a otras especies, pero pocos estudios han examinado las funciones que desempeñan en la comunidad de vertebrados de humedales. Estudiamos la diversidad, la frecuencia de aparición y las conductas de los vertebrados en las estructuras de la rata almizclera en la región Sandhill de Nebraska. Mediante cámaras trampa, registramos más de 37,700 observaciones de vertebrados, que representaban a 57 especies, incluidos anfibios, mamíferos, reptiles, aves canoras, rapaces y acuáticas. En las estructuras los vertebrados mostraron conductas de asoleo, copula, despliegue, forrajeo, acicalamiento, percha, limpieza, crianza, descanso y vocalización. En las Sandhills de Nebraska, las ratas almizcleras crearon hábitats insulares beneficiosos tanto para las especies migratorias como para las locales, siendo de especial importancia para las funciones de historia de vida de muchas aves acuáticas y tortugas. Las ratas almizcleras representan a los ingenieros del ecosistema, ya que sus estructuras fueron las únicas islas naturales en los humedales debido a la falta general de árboles y rocas en la región. Con frecuencia observamos el uso de las estructuras por múltiples especies simultáneamente, lo que sugiere que las estructuras insulares son limitadas en los humedales de Sandhill. Nuestro estudio resalta el gran número de vertebrados que utilizan las estructuras de las ratas almizcleras para una serie de funciones ecológicas y de historia de vida. A lo largo de la distribución de la rata almizclera, es probable que muchas otras especies utilicen y dependan de estas estructuras insulares, ya que la rata almizclera es un componente integral de muchos ecosistemas de humedales en Norteamérica. El comprender cómo otros animales silvestres utilizan estas estructuras y su frecuencia de uso es esencial a la hora de gestionar las poblaciones de rata almizclera y los humedales donde habitan estos mamíferos.

In this study, we explore two mycorrhizal groups during development of riparian soils along a freely-flowing river. We provide the first documentation of a shift in abundance between arbuscular mycorrhizae and ectomycorrhizae during floodplain succession. We used a chronosequence spanning 0-70 yr along a river in northwestern Montana, USA, to test the hypothesis that abundance of arbuscular mycorrhizal fungi (AMF) is greatest in early stages of soil development, and abundance of ectomycorrhizal fungi (ECMF) is greatest later in floodplain succession. We also measured the AMF-mediated process of formation of soil aggregates during site development. AMF colonization of the dominant tree (black cottonwood, Populus trichocarpa) remained low (<5%), while AMF colonization of understory species was high (45-90%), across the chronosequence. Mycorrhizal inoculum potential (MIP) and hyphal length of AMF in soil peaked within the first 13 yr of succession and then declined. No single variable significantly correlated with AMF abundance, but AMF tended to decline as litter and soil organic matter increased. Density of ectomycorrhizal root tips in soil increased linearly throughout the chronosequence, and ectomycorrhizal colonization of cottonwood roots increased rapidly in early stages of succession. These patterns suggest that ECMF are not limited by dispersal, but rather influenced by abundance of host plants. Formation of water stable aggregates increased rapidly during the first third of the chronosequence, which was the period of greatest AMF abundance in the soil. The peak in AMF infectivity and hyphal length during early succession suggests that regular flooding and establishment of new sites promotes AMF abundance in this ecosystem. Regulation of rivers that eliminates creation of new sites may reduce contributions of AMF to riparian areas.

Migratory birds use numerous strategies to successfully complete twice-annual movements between breeding and wintering sites. Context for conservation and management can be provided by characterizing these strategies. Variations in strategy among and within individuals support population persistence in response to changes in land use and climate. We used location data from 58 marked Whooping Cranes (Grus americana) from 2010 to 2016 to characterize migration strategies in the U.S. Great Plains and Canadian Prairies and southern boreal region, and to explore sources of heterogeneity in their migration strategy, including space use, timing, and performance. Whooping Cranes completed ∼3,900-km migrations that averaged 29 days during spring and 45 days during autumn, while making 11–12 nighttime stops. At the scale of our analysis, individual Whooping Cranes showed little consistency in stopover sites used among migration seasons (i.e. low site fidelity). In contrast, individuals expressed a measure of consistency in timing, especially migration initiation dates. Whooping Cranes migrated at different times based on age and reproductive status, where adults with young initiated autumn migration after other birds, and adults with and without young initiated spring migration before subadult birds. Time spent at stopover sites was positively associated with migration bout length and negatively associated with time spent at previous stopover sites, indicating Whooping Cranes acquired energy resources at some stopover sites that they used to fuel migration. Whooping Cranes were faithful to a defined migration corridor but showed less fidelity in their selection of nighttime stopover sites; hence, spatial targeting of conservation actions may be better informed by associations with landscape and habitat features rather than documented past use at specific locations. The preservation of variation in migration strategies existing within this species that experienced a severe population bottleneck suggests that Whooping Cranes have maintained a capacity to adjust strategies when confronted with future changes in land use and climate.

American beavers (Castor canadensis) are emblematic of diverse and dynamic freshwater ecosystems across North America. Numerous studies have described positive associations between beaver-modified habitats and biodiversity across a wide range of taxa. Yet few studies have documented biodiversity associated with the epicenter of beaver-modified habitats – the beaver lodge. We used an internet-connected, solar-powered, time-lapse camera system to examine daily and seasonal temporal partitioning amongst vertebrate taxa that visited an American beaver lodge in south-central Nebraska over 9 mo. We observed at least 28 species on the lodge, and many organisms were present during discrete daily and seasonal time periods. These observations provide a more holistic view of a widely recognized, yet understudied, component of beaver-modified habitats. Future use of similar visual-recording systems may reveal that other animal structures, such as burrows, nests, and hives, are prominent ecosystem components in the wild.

The Platte River caddisfly (Ironoquia plattensis) is a semiterrestrial limnephilid that inhabits sloughs along the Platte River in central Nebraska (USA). The species was discovered in 1997, and little is known about what controls its limited distribution or threatens its existence. We investigated effects of grazing by cattle (Bos taurus) on caddisfly abundance in a grassland slough. In April 2010, we established exclosures to isolate cattle from areas with caddisflies. We measured aquatic larval densities in April 2010 and 2011. We estimated grazing intensity from the normalized difference vegetation index (NDVI) values extracted from aerial images made in autumn 2010. Grazing intensity varied among plots, but ungrazed plots had more vegetation (higher NDVI values) than grazed plots. In April 2011, larval densities were greater in ungrazed than in grazed plots. Larval densities and NDVI values were strongly positively correlated, a result suggesting that reduction in vegetative cover from grazing was associated with decreased densities of caddisflies. Increased vegetative cover may have provided structure needed for adult courtship and inputs of organic matter to support larval feeding. Repeated, season-long grazing may have long-term negative consequences for the Platte River caddisfly in grassland sloughs when vegetation does not recover and other effects of cattle persist year after year. Resting pastures from grazing to permit vegetation to rebound appears to allow cattle and Platte River caddisflies to coexist in sloughs along the Platte River.