Geology topics

Research about United States

Source-linked reports with geographic coverage including United States.

At least 1,135 records · Page 63Linked to original sources

USGS2025

Geochemical evidence for the origin of late Quaternary loess, Seward Peninsula, Alaska

Loess is the most widespread surficial deposit in the state of Alaska. Although loess of last glacial age is common in mid-continental North America, records of last glacial loess in Alaska have been elusive. Here we report a record of last glacial loess on the Seward Peninsula, along with studies of a transect of loess localities also thought to date to the last glacial period. Highly diverse hypotheses on the origin of loess on the Seward Peninsula include local volcanic rocks and mountain ranges to the north and south, as well as offshore deposits. We present particle size and mineralogical and geochemical data that indicate that the most likely sources for loess in this part of eastern Beringia are glaciogenic silt particles of the Kobuk River and Noatak River, both of which drain the Brooks Range to the northeast. Northeasterly paleowinds were therefore responsible for loess on the Seward Peninsula. Such winds probably occurred during late summer or early autumn, when river discharge was at a minimum but temperatures were still above freezing. Northeasterly winds during the last glacial period are in good agreement with a recent paleoclimate model.

Alaska↗

USGS2025

The interface between rare plant management and genetics: Conserving Pitcher’s thistle (Cirsium pitcheri) in the Great Lakes region, USA

Background and Aims Tools showing best conservation practices are becoming critical for rare plant conservation as populations become isolated through habitat fragmentation and changing ecosystem processes. We illustrate the importance of reintroduction and assisted gene flow, using reintroduction of the USA federally threatened Pitcher’s thistle ( Cirsium pitcheri ), a monocarpic perennial endemic to the western Great Lakes sand dunes. We evaluate the success of experimental reintroductions of this species into its dynamic coastal environment and address fundamental issues for rare plant reintroduction, including questions of maintenance of genetic diversity, founder size, introduction methods and assisted gene flow effectiveness. Methods In 1994 we initiated experimental reintroductions at three new locations along a habitat successional gradient using 4200 seeds collected from 54 maternal lines. At each site, seed sources were distributed among replicate blocks that were split by sowing method (sowing vs broadcasting) to examine establishment success. We monitored population demography for 30 years, assessing genetic variation in 2009 and regionally from 1997 to 2014. Key Results Two of three populations persisted for 30 years from a single-seeding founder event. Reintroduction populations had greater expected heterozygosity than regional native populations. Despite persistence, moderate inbreeding coefficients showed that reintroduction populations have not achieved an effective size to reduce the likelihood of inbreeding depression. However, the mid-successional reintroduction had the lowest kinship of all populations sampled, indicating a healthy restoration. Seed sowing produced three times as many seedlings as broadcasting, but seed source did not affect germination success. Persistence has been facilitated by local migration to suitable habitat patches, an important metapopulation process. Conclusions Seeds can be an effective method for reintroducing monocarpic plants in high-quality habitats. However, low numbers of reproductive adults and moderate inbreeding illustrate the need for repeated additions of plants or seed to reduce inbreeding to improve rare plant genetic evolutionary potential.

Indiana↗

USGS2025

Satellite assessment of winter cover crop and conservation tillage outcomes to support adaptive management in working landscapes

The use of winter cover crops and conservation tillage are agricultural practices promoted to reduce nutrient and sediment loss from cropland, improve soil health, increase infiltration, and support farm nutrient cycling and ecosystem services. However, environmental performance of these practices is variable in the working farm landscape. The Lower Chesapeake Bay research project within the USDA Long-Term Agroecosystem Research (LTAR) network has collaboratively developed satellite remote sensing algorithms to measure the performance and phenology of winter cover crops (aboveground biomass, nitrogen content, fractional cover, and emergence and termination dates) using no-cost Harmonized Landsat and Sentinel-2 multispectral satellite imagery. This research supports annual operational assessment of >28,000 fields per year in four states. Results document the impacts of agronomic management on conservation outcomes, support adaptive management of incentive payment structures, and can reduce the workload for conservation district staff by remotely verifying cover crop management. Additionally, super-spectral satellite applications have been developed to accurately map crop residue cover by measuring lignocellulose absorption in shortwave infrared wavelengths, producing a 7-year time series of tillage intensity maps for the Delmarva Peninsula. These remote sensing products can be used in decision support and modeling to estimate changes in nutrient, sediment, and carbon cycling resulting from conservation practice implementation in the working farm landscape. This manuscript provides an overview of remote sensing research findings and applications associated with the USDA LTAR and Conservation Effects Assessment Projects (CEAP), documenting a variety of previously published outcomes with update and expansion of techniques using additional unpublished data and analyses as appropriate.

Maryland↗

USGS2025

Mount Spurr volcano, August 18, 1992: The eruption heard around Alaska

The August 18, 1992, eruption of Mount Spurr volcano, Alaska, produced an impressive Vulcanian to Subplinian eruption column reaching up to 40 km above sea level that blanketed the nearby city of Anchorage with ash. At the time of the eruption, the Alaska Volcano Observatory received reports of audible sound hundreds of kilometers from the source from a variety of azimuths from the volcano and found the pattern that did not solely depend on distance. Explosions are generally inaudible to the human ear at these distances due to the attenuation of sound in the atmosphere as the energy propagates, but low-frequency sound waves (infrasound) persist and can be used to detect and characterize eruptions. Similar reports of zones of audible sounds at great distances have been observed from notable eruptions such as Krakatau 1883, Mount St. Helens 1980, Mount Pinatubo 1991, and Hunga volcano 2022. We perform infrasound propagation modeling to help understand the unique distribution of audible reports, finding that areas with favorable infrasound propagation may help explain areas in which nonlinear propagation, including energy cascading effects into higher frequencies that are audible to the human ear, may have occurred.

Alaska↗

USGS2025

Expression and mechanisms of behavioral plasticity in large mammals

Behavioral plasticity, the alteration of behavior in response to stimuli, is becoming increasingly important in the context of human-induced rapid environmental change. Theoretical and empirical studies suggest that the expression and magnitude of behavioral plasticity are likely facilitated or constrained primarily by two factors: environmental variation and endogenous traits such as body size. The contextual role of these factors on behavioral plasticity, however, is poorly understood; there are relatively few studies that have compared the magnitude and potential drivers of behavioral plasticity at different levels (i.e., population and individual) across species, especially in free-ranging animals with diverse behavioral traits such as large mammals. Here, we quantify and test potential hypotheses for the mechanisms underpinning behavioral plasticity at the individual and population level in response to variation in summer temperatures for 1068 animal-years in 17 populations across nine species of large mammals. All populations displayed behavioral plasticity in response to increased temperatures, modifying their relative selection for heat-relieving habitat attributes (e.g., elevation) and heat-generating behavior (i.e., movement speed). We found strong support for the hypothesis that the variability of the physical environment is an important driver of behavioral plasticity—both mean population behavioral plasticity and variation among individuals within each population in plasticity were lower with increased heterogeneity of habitat attributes such as tree cover. Yet, the variability in environmental conditions (i.e., the magnitude of the temperature increase) had no effect on behavioral plasticity within and among populations. We did not detect an effect of endogenous traits on the expression of behavioral plasticity; however, we note that data availability limited our tests of this hypothesis to a select few endogenous traits (body size, feeding guild, and sex of the tracked individuals) that predominantly vary at the species level, for which we had one to three replicate populations per species. Our results provide an integrative and generalizable understanding of the expression of behavioral plasticity among populations of large mammals in temperate environments and emphasize the important but nuanced role of environmental variation in determining the scope of behavioral plasticity in these populations.

Wyoming↗

USGS2025

Red spruce forest stand structure and Virginia northern flying squirrel habitat suitability

The Virginia northern flying squirrel ( Glaucomys sabrinus fuscus ; VNFS) is a rare, Pleistocene-relict, disjunct subspecies of the northern flying squirrel. The squirrel occurs only in high-elevation red spruce ( Picea rubens ) forests of the central Appalachian Mountains of Virginia and West Virginia—a forest type that was substantially reduced by exploitative logging and wildfire in the 1890s–1930. Owing to its cryptic nature and difficulty of capture, managers have relied on an evolving series of predicted habitat suitability models that primarily have used topographic measures and red spruce cover class to assess potential occupancy on the landscape. Currently, VNFS is considered the sentinel species in the region whereby its predicted presence indicates red spruce forests with higher relative habitat integrity, and unsuitable habitat highlights where red spruce restoration or enhancement should occur. However, extant VNFS models only use red spruce percent composition and do not provide insights into forest structure, such as forest canopy height or basal area, that are needed by managers to implement restoration or assess effectiveness. We examined recent historical VNFS observations from nest-box surveys and radiotelemetry data (natural dens and foraging points) relative to random pseudoabsence points across red spruce cover classes from the most current VNFS predicted probability habitat model. Using generalized linear models in an information-theoretic approach, we found that within each red spruce composition class, suitable VNFS habitat was related to increased forest canopy height (m), basal area (m 2 ·ha −1 ), quadratic mean diameter (cm), and stem density (number of trees ha −1 ), indicating that, within red spruce and mixed red spruce–northern hardwood forests, VNFS is associated most with mature forest conditions. Accordingly, our results could be recombined with habitat suitability models to prioritize where, for example, red spruce forest structural enhancement would facilitate shifting a given stand to a higher probability condition for VNFS use.

Maryland, Virginia, West Virginia↗

USGS2025

Seasonal body mass dynamics mediate life-history trade-offs in a hibernating mammal

1. Energetic acquisition and growth are key traits that affect demography and life-history strategies. Many animals that live in seasonal environments in which food availability fluctuates store energy endogenously as fat in anticipation of food shortage. Fat-storing mammalian hibernators are an extreme example of this strategy where the optimal resolution of resource allocation trade-offs is essential to survival. Hence, these species provide an opportunity to test potential causes and consequences of seasonal body mass dynamics. 2. We used a 12-year dataset with 8753 body mass records from 3351 individually marked northern Idaho ground squirrels ( Urocitellus brunneus ) – a federally threatened hibernator – to meet three objectives: (1) document seasonal body mass changes by sex, age, and reproductive status, (2) test ecological hypotheses to explain spatiotemporal variation in body mass, and (3) document fitness consequences of pre-hibernation body condition via condition-dependent overwinter survival. 3. Squirrels varied substantially in seasonal body mass dynamics. The magnitude (36-155%) and onset (late May to early July) of rapid active-season mass gain varied among demographic groups. Reproductive females acquired the necessary fat stores to survive hibernation later in the active season than did males and non-reproductive females. Moreover, squirrels with better pre-hibernation body condition were more likely to survive to the subsequent year, potentially because they allocated excess energetic reserves to prolonging hibernation via early immergence and thereby reduced predation risk. These results suggest a direct trade-off between current and future reproduction mediated by resource acquisition and allocation, as predicted by life-history theory. 4. Colder active-season temperatures and lower conspecific densities negatively influenced squirrel body condition, possibly via reductions in foraging activity associated with those conditions. These ecological effects on body condition constrain resource allocation and demographic outcomes. As such, our results can help guide research and conservation strategies to benefit hibernating animals.

Idaho↗

USGS2025

Advancing climate adaptation for inland fish and fisheries

Climate change was barely a blip on the radar for inland fisheries management 20 years ago. Today, it's a central focus. A 2016 paper helped shift conversations, sparked adaptation efforts across fisheries management. The future is still uncertain, but adaptation is key to sustaining these important resources.

Wisconsin↗

USGS2025

Rare earth element-mineralized carbonatite in the Bear Lodge Alkaline Complex, USA—Ore genesis implications from fluid inclusion characterization

Rare earth element (REE) resources of the Bear Lodge Alkaline Complex, Wyoming, are hosted in variably leached carbonatite spatially related to diatreme breccia pipes. We investigated the genesis of REE and lesser-known gold resources through fluid inclusion analysis of carbonatite, fluorite breccia, and smoky quartz vein samples. Physicochemical characteristics of inclusion-trapped fluids were evaluated using petrography, microthermometry, Raman spectroscopy, decrepitate mound analysis, energy-dispersive spectroscopy, laser ablation inductively coupled plasma mass spectrometry, and noble gas isotope analysis. Microthermometry results reveal three fluid types that affected carbonatite dikes within deeper zones that escaped near-surface, ore-grade REE enrichment: (1) high-temperature (330–432°C) magmatic fluid captured in fine-grained calcite; (2) REE-enriched alkali bicarbonate-sulfate brine; and (3) low-temperature (117–182°C) diluted magmatic or meteoric water. Multiphase brine-like inclusions contain burbankite, nahcolite, strontianite, celestine and alkali sulfate daughter crystals, linking them to early burbankite mineralization. Peripheral smoky quartz and fluorite occurrences at Smith Ridge, 1.5 km from the central carbonatite dike swarm, contain primary inclusions that are Cl-poor and rich in Na-HCO 3 -SO 4 , similar to secondary and pseudosecondary inclusions in carbonatites. Helium isotopes reveal a MORB-like source for carbonatite samples and an older crust signature at Smith Ridge, consistent with the proximal ridge-top exposures of Archean granite. Results from this fluid inclusion study coupled with previous studies of carbonatite mineral paragenesis, show that light REEs (LREEs) were not mobilized great distances. Instead, burbankite crystallized within carbonatite from alkali bicarbonate fluids. With sodium retained in early burbankite, outward-emanating fluids enriched in potassium relative to sodium (higher K:Na) resulted in potassium–ferric iron metasomatism of silicate host rocks. This alkali fractionation was accompanied by fractionation of LREEs and heavy REEs (HREEs), with LREEs dominating the central carbonatite resources. In contrast, areas of peripheral REE mineralization at Bear Lodge are commonly characterized by higher HREE:LREE ratios. The K:Na ratio of associated fenites or alteration assemblages could be indicative of early crystallized burbankite in carbonatites and REE fractionation processes potentially leading to areas of concentrated HREEs with greater supply vulnerabilities.

South Dakota, Wyoming↗

USGS2025

Tracing invasion routes of Cuban treefrogs into Louisiana using mitochondrial DNA

Understanding the origin and spread of invasive species is critical for predicting when and where new introductions will establish, and impact native species. However, due to the complexity of contributing factors such as multiple introductions, dispersal method, genetic admixture in founding populations, and variable propagule pressure, genetic patterns observed in invasive species may not always conform to a single theoretical expectation. Cuban treefrogs ( Osteopilus septentrionalis ) are invasive in peninsular Florida and sporadically in the Florida panhandle. Though O. septentrionalis has been occasionally reported in Louisiana since the 1990s, established populations were not present until the discovery of a breeding population in New Orleans in 2017. In this study we investigated the source of this novel population using existing and newly generated cytochrome B (cyt-b) mitochondrial gene sequences from the native and invasive range of O. septentrionalis . We recovered a total of 14 cyt-b haplotypes, nine novel and five previously published. Within the 95 Louisiana invasion samples, we recovered seven haplotypes including five novel haplotypes. The haplotypes most common in Louisiana were shared exclusively with west and east Florida localities in central Florida, indicating a possible source population. The presence of haplotypes private to the Louisiana locality suggests other unsampled localities may also be contributing to the Louisiana settlement. Metrics of genetic diversity across native and invasive localities did not significantly differ. Furthermore, the Louisiana samples had higher genetic diversity than any single location sampled within Florida. Thus, genetic diversity and our haplotype connectivity suggest the Louisiana population is derived from multiple introductions from Florida. Our study highlights how demographic and genetic analyses can be utilized to understand the source and future expansion potential of invasive populations.

Florida, Louisiana↗

USGS2025

A model for regional-scale oak savanna management: The roles of fire, canopy, and soils for understory plant diversity

Predicting the outcomes of land management on biodiversity is difficult without a mechanistic understanding of how management approaches, ecosystem structure, environmental conditions, and biodiversity interact. Management effects may be direct or indirect, context- or scale-dependent, or obscured by local environmental conditions. Resolving these relationships at the regional scale may be difficult, given heterogeneity in local environmental conditions, yet understanding broad-scale patterns can elucidate context dependencies and improve restoration outcomes. We confronted these challenges within globally rare oak savannas in the midwestern United States, which have been altered by fire exclusion and resulting woody encroachment. By modeling direct and indirect pathways by which management influences diversity, we test a general framework for savanna restoration. Across 100 oak savannas spanning five US states, management by prescribed fire and mechanical thinning of woody vegetation affected groundlayer plant species richness through changes to ecosystem structure (canopy openness and litter depth), and these effects were both context- and scale-dependent. Frequent prescribed fires and canopy thinning promoted greater canopy openness, which in turn increased richness at small (1 m 2 ), but not larger (1000 m 2 ) scales. Frequent fire additionally increased richness at small and larger scales through effects independent of ecosystem structure. While management effects were large relative to the influence of local edaphic conditions, soil productivity had two largely offsetting effects on small-scale richness, increasing richness directly but decreasing richness indirectly by promoting closed canopy structure. These results suggest using a combination of fire and canopy thinning to reverse the effects of decades of fire exclusion. However, management effects were also context-dependent, emphasizing that management outcomes vary regionally. Here, 1-m 2 plant species richness increased with both fire frequency and canopy thinning under low, but not high, productivity soil conditions. By demonstrating how specific management practices influence savanna structure and biodiversity by manipulating ecological processes across broad geographic and edaphic gradients, our findings provide a framework for understanding management outcomes at short and medium intervals (e.g., within and between decades, respectively), in the form of a model that can be refined by testing additional hypotheses to better predict savanna restoration outcomes.

Illinois, Indiana, Michigan, Ohio, Wisconsin↗

USGS2025

Impact of warming and suspended terrigenous sediment on the Hawaiian reef coral Montipora capitata

Coral reefs near high human population areas suffer from sedimentation and increased turbidity due to coastal development. However, there is limited research on how key species respond to turbidity caused by terrigenous sediment and how this response may change with increased water temperatures. This study investigated the effects of ambient and elevated turbidity (+ 26 NTU) in combination with ambient (27.1 °C) and elevated temperature (+ 4.1 °C; 31.2 °C) on the dominant Hawaiian reef coral Montipora capitata , collected from two Kāneʻohe Bay watersheds with distinct environmental histories. Using intermittent flow respirometry, we found that acute (12 h) exposure to elevated turbidity and temperature impacted algal symbionts ( Symbiodinium spp. ) but not the coral host, suggesting a potential delayed host physiological response. Corals from south Kāneʻohe Bay, where restricted water circulation and urbanization have degraded water quality, were more sensitive to stressors than those from the less-impacted northern sites, indicating that physiological responses vary by location and may be influenced by watershed conditions. The findings suggest that while short-term turbidity and warming impact Symbiodinium spp. immediately, prolonged exposure may lead to cascading effects on the coral host. Understanding these species-specific and location-dependent responses enhances our ability to guide restoration and conservation efforts for coral ecosystems facing both local (turbidity) and global (warming) stressors.

Hawaii↗

USGS2025

S/P amplitude ratios with Distributed Acoustic Sensing and application to earthquake focal mechanisms

Distributed acoustic sensing (DAS), which transforms a fiber optic cable into an array of high frequency strainmeters, has the potential to help us characterize earthquakes with a dense sampling of measurements. While earthquake focal mechanisms are frequently determined using P -wave polarities and S / P amplitude ratios with inertial seismometers, the dense sampling of DAS over potentially large portions of the focal sphere can aid our solutions. Here, we consider ∼200 regional earthquakes and thousands of S / P measurements on a DAS cable colocated with a network of inertial seismometers near Arcata, California. We demonstrate the S / P ratio measurements made on DAS are similar to those made on the inertial seismometers and can be used to constrain focal mechanism solutions.

California↗

USGS2025

Subduction zone earthquake catalog separation tool: Implementation in the USGS 2025 Puerto Rico and U.S. Virgin Islands National Seismic Hazard Model

The U.S. Geological Survey (USGS) periodically releases updates to National Seismic Hazard Model (NSHM) for the United States and its territories leveraging current scientific knowledge and methodologies to guide public policy, building codes, and risk assessments regarding potential ground shaking due to earthquakes that may result in infrastructure damage. In subduction zones, there is a need to separate the earthquake catalog into tectonic regimes to create specific seismicity models for which the most appropriate ground‐motion models are then applied. Here, we describe newly developed methods and software, called CatSep, that classifies subduction zone events into three primary tectonic regimes: crustal, interface, and intraslab. This method incorporates information about the location of the earthquake relative to the subducting slab, the depth of the Mohorovičić discontinuity, and the earthquake’s moment tensor. Applying this method is a first step in the NSHM workflow for regions covering U.S. subduction zones. Results using this subduction zone earthquake catalog separation tool for the 2025 Puerto Rico and U.S. Virgin Islands NSHM earthquake catalog are presented and analyzed.

Puerto Rico, U.S. Virgin Islands↗

USGS2025

A short-term sublethal oral exposure to microcystin-LR disrupts cecal microbiome homeostasis in mallard

Introduction: The frequency of cyanobacterial blooms seems to have increased globally in recent decades due to human induced eutrophication and climate change. Cyanobacterial blooms can produce several groups of toxins, among which microcystin-LR (MC-LR) is one of the most abundant. Effects of MC-LR on avian microbiome have not been studied and studies in laboratory murines have been limited to metabarcoding of prokaryotes. Methods: Using RNA shotgun sequencing, we compared the richness and composition of metabolically active prokaryotes, expressed virulence factors, antimicrobial resistance genes, metabolic pathways, Gene Ontology terms, enzymes, and proteins in mallards (Anas platyrhynchos) that were orally exposed to a sublethal dose of MC-LR for one week and unexposed birds. Results: Richness and composition of all compared features did not differ between exposed and control birds and none were differentially expressed between exposure groups. However, richness and/or composition of all features except virulence factors and Carbohydrate Active enzymes had multiple-fold greater dispersion in exposed birds than in controls. This effect was especially pronounced in expressed metabolic (MetaCyc) pathways. Discussion: Our results suggest that MC-LR exposure had a stochastic (rather than deterministic) effect on cecal microbiota, especially its function. Observed disturbance of the microbiota homeostasis is consistent with the Anna Karenina Principle. This principle has been documented in a wide range of eukaryotes using primarily microbial community metabarcoding. Although stochastic disturbance of microbiota function has been hypothesized, our study seems to be the first to demonstrate this in an experimental study.

Wisconsin↗

USGS2025

Exploring the exploitation of migratory moths by radio-marked grizzly bears in Wyoming

Grizzly bear ( Ursus arctos ) feeding on migratory army cutworm moths ( Euxoa auxiliaris ) was first documented by the Interagency Grizzly Bear Study Team (IGBST) during the early 1980s in the southeastern portion of the Greater Yellowstone Ecosystem (GYE). Since those initial observations, use of this seasonally available food resource by grizzly bears has grown substantially. As of 2023, we have documented 4,754 observations of grizzly bears feeding or digging at high-elevation talus slopes. We used those records to identify 36 unique moth sites in the GYE, assessed geographic characteristics of these sites, and documented chronology and frequency of use by grizzly bears. We used occurrences of radio-collared grizzly bears to identify a sample of bears that foraged at moth sites and investigated characteristics of fidelity, duration, diel activity, and movement patterns. Grizzly bears exhibited high fidelity to specific moth sites within and across years. Bears showed approximately 50% reductions in movement metrics while using sites, albeit with increased activity patterns. Estimates of feeding metrics by females exceeded those of males in intensity and duration of both use and daily activity. Given increasing human impacts and interest in observing this feeding interaction, quantifying metrics that describe the spatial and temporal patterns of moth site use by grizzly bears could be beneficial for future management. Further analyses are needed to fully examine the relationship between caloric influences of moth use on grizzly bear demographic rates.

Idaho, Montana, Wyoming↗

USGS2025

Evaluating effectiveness of flocculation and wave-reduction barriers for restoration of a turbid, terminal lake

Malheur Lake is a freshwater, shallow lake that provides key habitat for birds along the Pacific Flyway in North America. The lake shifted to a turbid state in the 1990s with suspended-sediment concentrations sometimes exceeding 1000 mg/L and minimal light available in the water column for submerged aquatic vegetation. Resource managers intend to enhance bird habitat quality by restoring the lake to a clear, vegetated state. Ten mesocosms were installed to experimentally test the effects of wave-reduction barriers and flocculation (aluminum sulfate followed by lanthanum-modified bentonite clay) on dependent variables including turbidity, suspended-sediment concentrations, nutrient concentrations, and photosynthetically active radiation. Flocculation additions temporarily decreased turbidity by ≥ 90% and significantly increased photosynthetically active radiation by > 400% through the water column. Orthophosphate concentrations significantly decreased following the first flocculation addition. The clay did not cap the flocculated material, and turbidity increased within a few days from wind-wave action. Wind directions in the middle of the lake were variable, minimizing the effect of wave-reduction barriers on dependent variables. This study showed that the light required for submerged aquatic vegetation can be temporarily attained at the lakebed using flocculation. Future experiments could attempt to prolong the duration of low turbidity by effectively capping the flocculated material. The findings demonstrate the complexity of disrupting shallow lake feedback loops and offer insights for turbid-state lake restoration.

Oregon↗

USGS2025

Beyond habitat: Memory versus environment in shaping animal space use

For nearly half a century, ecologists have sought to explain animal space use through characteristics of the environment (i.e., habitat). Recent evidence suggests animals also use memory of previous experiences to decide when and where to move. Yet, the relative influence of the two in explaining animal space use has not been resolved. Using six large ungulate species in the Rocky Mountains (USA), we evaluated the performance of a habitat selection model with 16 environmental variables and another with two variables representing previous use (i.e., memory). While memory outperformed the environment for two species and the environment outperformed memory for four species, the influence of memory and the environment was overall comparable. The environment best explained the space use of specialists, while memory best explained species with strong site fidelity. Our work challenges traditional habitat selection theory, showcasing that animals build their spatial preferences through experience just as much as merely responding to their environment.

Wyoming↗