Geology topics

Research about United States

Source-linked reports with geographic coverage including United States.

At least 163 records · Page 9Linked to original sources

USGS2026

Geolocator devices did not affect chick growth or adult return rates in Wedge-tailed Shearwaters (Ardenna pacifica) despite interannual variation in chick development

Although biologging has transformed seabird ecology, bird-borne devices could alter the behaviors being studied, including parental care. We tested for effects of leg-mounted light-level geolocators (< 1% of body mass) on chick growth and adult return rates in Wedge-tailed Shearwaters (‘ua‘u kani, Ardenna pacifica ) breeding on O‘ahu, Hawai‘i during two consecutive breeding seasons that coincided with contrasting El Niño Southern Oscillation (ENSO) years. Accounting for hatching phenology, we compared three responses of two tagging groups (tagged and non-tagged controls): (1) chick growth rates (mass, wing chord, 10th primary), (2) chick survival to fledging, and (3) adult return rates in the following breeding season. We found a significant effect of year on overall chick growth patterns, but no effect of tagging or sex-specific impacts. Chick survival did not differ between groups in either year. Regardless of the tagging group, all chicks in 2023 grew wing chords more slowly and reached lower peak body mass compared to chicks in 2022. However, growth rates did not differ between tagging groups within either season. Despite these interannual differences in chick growth, geolocator deployments did not impact breeding performance or adult return rates to the colony. These results emphasize the importance of evaluating device effects to avoid misinterpreting interannual variability as a tagging impact, and reinforce the value of even small-scale comparisons of tagged and non-tagged groups.

Hawaii↗

USGS2026

An evaluation of transmitter effects on the return rate of adult and juvenile Common Terns to a breeding colony

Advancements in technology have facilitated a rapid expansion in the range of species for which tracking studies can be implemented. Such efforts often require unique attachment methods or materials for which careful evaluation is required to fully understand potential tagging effects and subsequent implications. During the 2021 breeding season, our research team affixed two types of light-weight transmitters to adult and pre-fledgling juvenile Common Terns ( Sterna hirundo ) with leg-loop harnesses made of elastic cord. Our initial observations of these marked birds detected minimal differences in behavior and nesting success of marked adults, and failed to detect any notable impacts on the growth rate or behavior of marked juveniles, but were limited to a single year of data. To provide further insight into the potential effects of these tagging methods, we evaluated return and nesting rates for the 2022 through 2025 breeding seasons. We found that all individuals observed on the breeding grounds in the years following transmitter attachment had not retained the transmitter. The observed tag loss suggest that tag retention could be considered when planning future efforts, and limits our analyses to understanding lagged effects of the unknown duration of actual attachment. With this limitation in mind, we found that birds marked as adults with center-weighted and rear-weighted tags were 1.00 and 0.76 times as likely, respectively, to return to the colony site, and 1.09 and 0.77 times as likely, respectively, to be observed nesting when compared with unmarked controls. Similarly, birds marked as juveniles with rear-weighted transmitters were 0.54 as likely to return, and 0.72 times as likely to nest in subsequent years. These results suggest no negative impacts of center-weighted attachment on return or nesting rates, but moderate support declines in both metrics for birds marked with rear-weighted transmitters.

Maryland↗

USGS2026

Advancing outreach effectiveness to improve conservation practice adoption

Agricultural conservation practices are central to achieving Chesapeake Bay watershed restoration goals, yet long-term adoption remains challenging even when practices are technically effective and financial assistance is available. Adoption is not a single decision, but a staged and context-dependent process. Awareness and willingness to commitment, implementation, and persistence, are all important. Progress along this pathway is influenced by interacting factors such as knowledge, attitudes, beliefs, social norms, trust, perceived risk, farm characteristics, and practical constraints. Improving adoption requires outreach strategies that respond to the specific factors limiting progress at each stage rather than relying on a one-size-fits-all approach.

Chesapeake Bay watershed↗

USGS2026

Landscape-scale drivers of bat acoustic activity in the interior mid-Atlantic

We assessed the landscape scale foraging habitat associations from a multi-year perspective using generalized linear mixed models for nine bat species using bat detectors in the interior mid-Atlantic region of Maryland and Pennsylvania, United States. The landscape use trends we detected included greater Eptesicus fuscus acoustic activity along field edges than in forested habitats, and greater Lasiurus borealis acoustic activity in xeric conditions rather than hydric/mesic conditions relative to aspect. Additionally, no bat species had a meaningful relationship with McNab’s Landform Index, atypical for Myotis septentrionalis. Our results also demonstrate that most bat species’ acoustic activity were stable over years though some counts were extremely low, attributable in part to population reductions from white-nose syndrome. We also observed variation of bat activity on the landscape throughout the active season. Eptesicus fuscus, M. lucifugus, M. septentrionalis, M. sodalis, and Perimyotis subflavus acoustic activity levels over the active season appear to be related to the annual reproductive cycle, i.e., pregnancy, lactation, and volancy of pups. Our study is indicative that bat acoustic activity can vary between regions and years, highlighting the need for more multi-year, locally focused research of bats.

Maryland, Pennsylvania↗

USGS2026

Recent high-severity wildfires in a dry-conifer landscape are unprecedented over five centuries and foretell future forest loss

Dry forests of the western United States evolved with frequent, spatially extensive, low-severity fires, followed by a century of fire exclusion. Recently, these same forests have experienced large and increasingly severe fires causing widespread forest loss. To what extent do modern high-severity fires depart from pre-1900 fire regimes, and how do these departures affect the future persistence of dry-conifer forests? We address these questions using a multiscalar approach that combines the largest landscape-scale tree-ring fire-scar network in North America with neutral landscape model simulations in the Jemez Mountains of northern New Mexico. Fire scars recorded a continuous 400-y history (ca. 1500–1900 CE) of frequent, low-severity fires across individual sites, landscapes, and centuries. We evaluated whether forests exhibiting this record could plausibly persist if they had historically burned under modern patterns of high-severity fire. Across the 240,000-ha Jemez landscape, high-severity fires from 1995–2024 burned 32% of fire-scar sites and 25% of dry-conifer forests. Within the Las Conchas Fire perimeter—a 61,000 ha area reburned by multiple fires—66% of fire-scar sites and 71% of forests were burned at high severity, erasing multiple centuries of forest and fire history. Simulations indicate that the probability of the observed fire-scar network persisting under modern high-severity fire rates is near-zero ( P < 0.001). Projecting these dynamics forward indicates rapid loss of both dry-conifer forests and tree-ring fire histories—50% of modern dry-conifer forest will remain by 2055, and 24% by 2115. Modern high-severity fire regimes appear incompatible with dry-conifer forest persistence.

New Mexico↗

USGS2026

Long-term monitoring and response of Papaipema sciata Bird (Lepidoptera: Noctuidae) to prescribed fire in Michigan (USA)

The Culver’s root borer moth ( Papaipema sciata ) (Lepidoptera: Noctuidae) is a rare Noctuid that requires Culver’s root ( Veronicastrum virginicum ) to complete its lifecycle within remnant native grasslands and open woodlands in the midwest and northeast United States. We report on 26 years of monitoring this species’ colonization of Culver’s root stems at Algonac State Park (ASP) in Michigan, where prairies have been maintained by prescribed fire since 1990. P. sciata is considered fire sensitive because eggs spend the dormant season in the combustible prairie litter and duff near host plants. The objectives were to determine the effect of prescribed burns, burn unit size, and local precipitation on P. sciata population size and abundance of host plant V. virginicum . The moth has one generation per year and exhibits low dispersal capabilities—traits which presumably inhibit recolonization of burned areas, particularly when they are patchy, fragmented, and separated by closed canopy forest or agricultural lands. P. sciata colonization (defined as the proportion of V. virginicum plants hosting larvae) and total V. virginicum stems, though spatially and temporally variable, appear stable. Our results suggest that P. sciata abundance increases when managers lengthen the time interval between fires in a given burn unit, but this effect appears to diminish after three years. We also found precipitation during the adult (egg-laying) phase of P. sciata ’s life-cycle is positively associated with colonization rate, while the inverse was true for annual cumulative precipitation across all life cycle phases. We did not find evidence that colonization rate increased with increasing host plant abundance, indicating that host plant population size is not a suitable proxy to assess population size of the moth. The data also support current temporal guidance regarding prescribed fire and Papaipema at ASP.

Michigan↗

USGS2026

The eruptive behavior of distributed volcanism forming low shield edifices—A case study of Sentinel-Arlington volcanic field, U.S.A.

Distributed volcanic fields are present in various tectonic settings worldwide, and their characteristics reflect differing influences from magmatic and tectonic processes. In the southwestern United States alone, there are 37 Quaternary distributed volcanic fields. After the primary period of extensional tectonics in the southern Basin and Range 15–5 million years ago, the Sentinel-Arlington volcanic field developed in southwestern Arizona between 4 and 1 million years ago. The Sentinel-Arlington volcanic field consists primarily of low relief shield volcanoes, a type of distributed volcanism with poorly understood temporal evolution. The Sentinel-Arlington volcanic field is less than 200 kilometers (km) from the Colorado Plateau, Gulf of California, and southern San Andreas Fault system. This work identifies and examines controls on the emplacement of the Sentinel-Arlington volcanic field by documenting shallow and surficial structures as well as eruption characteristics and style through time. The Sentinel-Arlington volcanic field consists of 21 volcanoes with a total of 33 vents over an area of about 770 square kilometers (km 2 ). The prominence of low relief shield volcanoes may be explained by ascent of basaltic magmas through thin Basin and Range crust, without much crustal contamination, and low viscosities common to mafic compositions. Typical eruption characteristics involve the construction of low relief shield volcanoes followed by Strombolian fissure eruptions at the summits or near-summit medial areas that produce scoria lapilli, which may weld to form agglomerate. The total lifetime erupted volume of about 4.3 cubic kilometers (km 3 ) represents an average eruptive flux of approximately 2x10 -3 km 3 per thousand years (k.y.). This erupted volume is low relative to Neogene basaltic intraplate distributed volcanic fields worldwide, which typically range from 10 -3 to 1 km 3 k.y. -1 . Sentinel-Arlington volcanic field eruptions were likely triggered by intermittent rejuvenation of transient magmatic zones that exist in thinned crust. Instantaneous flux from point sources feeding the lava flows is estimated to be on the order of 10 -1 to 10 cubic meters per second.

Arizona↗

USGS2026

Statewide surficial geologic map of Nebraska underscores Quaternary landscape evolution from the High Plains to the Central Lowland

Surficial geologic mapping in Nebraska has been conducted primarily at the 1:24,000 scale since the mid-1990s, although there have also been limited efforts to map generalized Quaternary and surficial geology within the state and the region. We compiled and evaluated disparate maps (1:24,000–1:1,000,000) and datasets—including geologic, soil and soil parent material, and geomorphic maps as well as LiDAR derivatives—to produce a single 1:500,000 scale surficial geologic map of Nebraska that is the first of its kind. This new map provides a coarse-scale surficial geologic map that will be incorporated into a nationwide U.S. Geological Survey Quaternary geologic map. It also reflects the variation and uniqueness of physical landscapes in the state, where the Great Plains and Central Lowland physiographic provinces meet, further developing a richer interdisciplinary understanding of regional geomorphology in the heart of North America.

Nebraska↗

USGS2026

Temporal replication and sampling efficiency in high-frequency autonomous and manual eDNA sampling

Environmental DNA (eDNA) sampling is a valuable tool for ecological research, but its reliability as a quantitative approach can be improved by accounting for unexplained spatiotemporal variability and autocorrelation in eDNA concentrations. Sampling designs with temporal replication can separate sampling variation from temporal variation, but obtaining true temporal replicates is difficult when samples are collected sequentially. Autosamplers may facilitate high-frequency eDNA sampling, but their sequential sampling structure raises questions about when closely spaced samples can reasonably be treated as temporal replicates. This 19.5-day study evaluated temporal variation in invasive Round Goby ( Neogobius melanostomus ) eDNA concentration at a single large-river site with short-term hydrologic variability. We used two synchronized autosamplers and a backpack sampler to collect samples as frequently as every 15 min using polyethersulfone (PES) or mixed cellulose ester (MCE) filters. We fit hierarchical temporal models that decomposed sampling and temporal variation, evaluated evidence for residual temporal correlation under alternative priors for the effective range, and used simulation to assess bias when closely spaced sequential samples were treated as simultaneous temporal replicates. We found evidence of residual temporal correlation at short lag scales, but the effective range of temporal correlation was weakly identified and sensitive to prior assumptions. Hydrologic covariates had limited explanatory support once temporal structure was accounted for. Simulations showed that treating sequential samples collected over 15–60 min windows as simultaneous temporal replicates can bias estimates of sampling and temporal variation, especially when temporal correlation is relatively weak. MCE filters produced higher expected recovered copy numbers than PES filters, while evidence for systematic differences among sampler types was weaker. These results emphasize that eDNA temporal replication should be collected as close together in time as possible, and that uncertainty in temporal correlation should be explicitly considered when designing and analyzing high-frequency eDNA surveys.

New York↗

USGS2026

The effect of temperature, flow, density and disease on smallmouth bass (Micropterus dolomieu) early life growth rate

Individual growth rates of fish are influenced by gradually changing environmental conditions and rapid-onset events. However, there is a paucity of information on drivers of spatiotemporal variability in growth rates of fishes across large spatial extents. Using a 36-year dataset of smallmouth bass ( Micropterus dolomieu ) length-at-age data across 10 river reaches in Pennsylvania, USA ( n = 54,068 individuals), we estimated annual early life growth rates (mm year −1 ) and assessed the effects of relative abundance, summer temperature, summer streamflow rate and a disease outbreak on growth rate. We found that temperature had a positive effect on growth rate, varied spatially, and had a stronger effect in diseased reaches. There was also evidence for an impact of disease on early life growth through density-dependent mechanisms, with growth rates increasing from ∼85 to 101 mm·year −1 following disease-related decreases in abundance. This study adds to our understanding of the factors that shape early life growth, including rapid-onset events like disease which can have immediate and lasting effects on growth rate trajectory.

Pennsylvania↗

USGS2026

Evaluating chlorophyll fluorescence sensors as a proxy for chlorophyll a concentrations in the Illinois River, Illinois, water years 2018–24

The U.S. Geological Survey deployed instream chlorophyll fluorescence sensors on the Illinois River in Illinois to better understand the formation, dynamics, and persistence of riverine algal blooms. At five sensor locations across four U.S. Geological Survey streamgages, chlorophyll fluorescence (fChl) sensors were set to measure instantaneous fChl in micrograms per liter as chlorophyll at 15-minute intervals. These sensors estimate fChl based on the fluorescence response of algal pigments but do not directly measure chlorophyll a (Chl) concentrations or algal biomass. To evaluate the reliability of fChl as a proxy for Chl, fChl measurements were compared to laboratory-measured Chl concentrations. These Chl concentrations were obtained from water-quality samples collected at the sensor locations and analyzed using the standard chromatographic-fluorometric method with acetone extraction. A total of 209 paired fChl and Chl observations were analyzed using Pearson’s correlation and model II regression. Statistically significant, positive correlations (Pearson’s correlation coefficient of 0.68–0.95) were detected at all sensor locations, indicating that fChl generally tracked with Chl. However, model II regression detected proportional and fixed bias at three of the five locations and proportional bias at another location. At locations with proportional biases, model II regression slopes were less than 1, indicating that fChl increasingly underestimated Chl as concentrations increased; however, paired observations at high Chl concentrations were sparse. Substantial variability in bias was also observed across sensor locations with slopes ranging from 0.43 to 0.93. Overall, the results indicated that fChl correlates well with Chl in the Illinois River, but fChl may not reliably represent Chl concentrations without adjustment. For applications requiring accurate Chl estimates, a sensor location-specific surrogate model could be beneficial. These findings underscore the importance of field validation, consistent sensor placement, and careful interpretation of fChl data, particularly when reported in micrograms per liter.

Illinois, Indiana, Wisconsin↗

USGS2026

Numerical modeling of Late Pleistocene to Holocene earthquake-induced progressive rock slope damage in the paraglacial Serpentine valley, Prince William Sound, Alaska

Landslides in deglaciating fjords pose a potential tsunami threat to nearby communities; however, processes contributing to long-term progressive rock damage and landslide conditioning remain poorly constrained in paraglacial settings. Here, we analyse the role of earthquake-induced rock mass damage over late Pleistocene to Holocene time scales, as a conditioning factor for modern landslides, using distinct element numerical modelling to assess spatial and temporal patterns of fracture propagation influenced by varying glacier thickness. Conceptualised numerical models were parameterised by in situ rock mass, glacial and topographic conditions in Serpentine valley, located in Prince William Sound, Alaska, where several large landslides are actively developing along the western valley wall. Results show that although rigid glacier buttressing reduces co-seismic rock mass damage, it does not suppress it completely, and damage occurs both above and below the glacier surface elevation. We demonstrate that topography, and especially steep slopes with topographic convexity, as well as preexisting damage of joint networks and faults inherited from tectonic and exhumation induced stresses, exert primary control on the location of new co-seismic damage. Simulations representing a simplified deglaciation sequence over the past 25 ka, with a series of 10 evenly spaced earthquakes, generated rock mass damage patterns that qualitatively match in situ landslide structural and kinematic observations at one instability in Serpentine valley. Our conceptual study helps clarify the role of repeated seismicity over glacial timescales as a long-term conditioning process for paraglacial rock slope failure, highlighting spatial and temporal patterns of progressive damage accumulation, with outcomes relevant for modern landslide hazard assessment.

Alaska↗

USGS2026

Rewilding the upper Klamath River Basin: Rapid recolonization of Chinook salmon following the world’s largest dam removal

Habitat fragmentation is a global driver of decline in biodiversity, yet evaluations of ecological response following re-connection remain rare. In 2024, four hydroelectric dams on the Klamath River were removed, reconnecting over 640 km of anadromous habitat and marking the largest dam removal project completed to date. We used a stationary high-resolution multi-beam imaging SONAR to quantify adult Chinook salmon ( Oncorhynchus tshawytscha ) passage into newly reopened reaches during the first two migratory seasons following dam removal. An estimated 7,742 (95% CI: 7,702–7,778) Chinook salmon migrated upstream in 2024 and 13,310 (95% CI: 12,876–13,733) in 2025, representing 18–19% of fish returning to the Klamath River Basin. Within this period, Chinook salmon recolonized 88% of their documented historical distribution, expanding into 345 km of reconnected habitats and reaching elevations of up to 1,250 m. Recolonization required fish to swim through dam removal sites, complex hydraulic corridors and engineered fishways, demonstrating the propensity for rapid recolonization at basin scale despite these challenges. These findings provide the first quantitative assessment of salmon response to the world’s largest dam removal and demonstrate how reconnection can catalyze large-scale recolonization in historically fragmented river networks.

California, Oregon↗

USGS2026

Streamflow, water quality, and constituent loads and yields, Scituate Reservoir drainage area, Rhode Island, water year 2023

As part of a long-term cooperative program to monitor water quality within the Scituate Reservoir drainage area, the U.S. Geological Survey, in cooperation with Providence Water (formerly the Providence Water Supply Board), collected streamflow and water-quality data in tributaries to the Scituate Reservoir, Rhode Island. Streamflow and concentrations of chloride and sodium estimated from records of specific conductance for 16 tributaries were used to calculate loads of chloride and sodium during water year 2023 (October 1, 2022, through September 30, 2023). Water-quality samples were collected by Providence Water at 38 sampling stations on tributaries to the Scituate Reservoir during water year 2023. These water-quality data are summarized by using values of central tendency and are used, in combination with measured (or estimated) streamflows, to calculate loads and yields of selected water-quality constituents for water year 2023. Annual mean streamflows for monitoring stations in this study ranged from 0.47 to 34.4 cubic feet per second during water year 2023. At the 16 continuous-record streamgages, tributaries transported about 3,000 metric tons of chloride and 1,900 metric tons of sodium to the Scituate Reservoir; annual chloride yields for the tributaries ranged from 19 to 200 metric tons per square mile, and annual sodium yields ranged from 13 to 120 metric tons per square mile. At the stations where water-quality samples were collected by Providence Water, the medians of the median daily loads were 65,000 million colony forming units per day for coliform bacteria, 870 million colony forming units per day for Escherichia coli , 200 kilograms per day for chloride, 8.2 grams per day as nitrogen for nitrite, 520 grams per day as nitrogen for nitrate, and 300 grams per day as orthophosphate for phosphate. The medians of the median yields were 25,000 million colony forming units per day per square mile for coliform bacteria, 600 million colony forming units per day per square mile for Escherichia coli , 65 kilograms per day per square mile for chloride, 4.6 grams per day per square mile as nitrogen for nitrite, 180 grams per day per square mile as nitrogen for nitrate, and 180 grams per day per square mile as orthophosphate for phosphate.

Rhode Island↗

USGS2026

Evaluating interactive effects of the Conservation Reserve Program and wind energy infrastructure on grassland bird abundance in the United States

The extent of grasslands has contracted globally, leading to significant declines in grassland-obligate species, including birds. Grassland birds are threatened by multiple factors, including grassland conversion to cropland, and development, including energy infrastructure. In the USA, the federal Conservation Reserve Program (CRP) provides financial incentives for agricultural landowners to convert marginal cropland to vegetative covers, including grassland, making it a key approach to recovering grasslands. However, given the high percentage of wind turbines near Conservation Reserve Program land, it is critical to determine if wind energy and the Conservation Reserve Program interact to affect grassland birds. We used generalized additive models and community science eBird data to assess the interactive effects of wind and the Conservation Reserve Program on the abundances of 27 grassland-obligate bird species across their breeding ranges in the continental US. We found associations between bird relative abundances and interactions involving wind and Conservation Reserve Program variables, suggesting that wind energy development near Conservation Reserve Program fields could dampen the benefits of the Conservation Reserve Program for some species. These results indicate that decisions about where to install wind energy infrastructure that incorporate information about the presence of Conservation Reserve Program land may reduce the adverse effects of wind energy on grassland birds. This study provides information that can help maximize the benefits of the Conservation Reserve Program while allowing for environmentally friendly development of renewable energy.

contiguous United States↗

USGS2026

Satellite embeddings for crop type classification: A comparative examination

Embedding datasets encode complex relationships among multiple sources of Earth observation data into a compact format. Here, we evaluated the utility of a 10-m global Satellite Embedding product (SE) for classifying crop types in central California for the year 2020. We compared the classification accuracy of a random forest model based exclusively on the SE layer to an existing random forest model with multiple imagery inputs. Our results showed the SE-based classification had higher agreement with the reference dataset (California Department of Water Resources crop map) than the classification based on Landsat and National Agricultural Imagery Program inputs (94.7% versus. 91.9% overall accuracy, respectively). The performance of individual crop types was consistent across models, ranging from high agreement for rice (98.4% versus 98% accuracy) to lower agreement for pasture, grain, and fallow/young perennial classes (< 65% accuracy in both models). The SE-based workflow used three times less cloud-based computational resources and represented substantial savings of predictor development time. Geospatial embedding products can aid classification efforts by reducing predictor development time and processing demands while maintaining classification accuracy.

California↗

USGS2026

Ductile and brittle Rio Grande Rift deformation in Oligocene granite records a two-stage rift history in southern Colorado

The timing and nature of early deformation in the Rio Grande Rift remains poorly constrained. We present evidence for the earliest structural signature of rift extension in the Sangre de Cristo Range, southern Colorado, based on new geologic mapping, structural analysis, rock magnetic data, and thermochronology. These analyses focus on the ~30.0 Ma granite of Chokecherry Canyon, which hosts discrete low-angle mylonitic shear zones and a distributed, gently SW-dipping protomylonitic fabric. Incremental stretching axes, stretching lineations, and Kmax magnetic lineations plunge gently WSW. Quartz microstructures and crystallographic orientations indicate dominantly coaxial strain in the protomylonite and general shear in the discrete shear zones. Quartz c-axis opening-angle thermometry suggests deformation at ~420–540°C. Thermal modeling of ⁴⁰Ar/³⁹Ar K-feldspar data indicates rapid post magmatic cooling below the brittle–plastic transition, supporting shear-zone formation immediately after emplacement. Slow cooling from ~20–13 Ma was followed by renewed rapid cooling at ~13 Ma, interpreted as the onset of extensional exhumation along the Sangre de Cristo Fault System. These results show that extension in the northern Rio Grande Rift was active by ~30 Ma, earlier than previously recognized. We propose a two-stage model for northern Rio Grande Rift evolution: Stage I (30–23 Ma) records ENE–WSW extension localized in low-angle mylonitic shear zones associated with mid-crustal intrusions; Stage II (≤18 Ma) reflects brittle high-angle normal faulting, focused exhumation, and rift narrowing. Stage I magmatism and deformation along the western range front likely established crustal weaknesses that guided later fault development.

Colorado↗

USGS2026

Predator hunting modes induce varied selection pressures on prey personality

Consistent individual differences in animal behavior—ie, personalities—have been documented in many taxa to have important fitness consequences in the context of predator-prey interactions. Multiple mechanisms have been suggested to maintain variation in prey personality traits, including life-history tradeoffs and divergent selection pressures from predators with different hunting strategies. However, empirical evidence for these hypotheses has been limited by a lack of data originating from complex multipredator systems in situ. To address this gap and evaluate these 2 mechanisms, we collected hispid cotton rats (Sigmodon hispidus) in the Florida Everglades and quantified 3 behavioral traits in the field. After releasing rats at their point of capture, we monitored their survival in their natural habitat where they faced threats from a diversity of ambush (snakes) and active predators (mammals; birds). Using Cox proportional hazards regression models and competing risks models, we assessed the effect of boldness, activity, and docility on rodent predation risk. Contrary to conventional predictions that bolder and more active individuals would face higher predation risk due to life-history tradeoffs, we found that the impact of these traits on prey survival varied with the predators' hunting modes: shyer, more active individuals were more likely to be killed by active predators, whereas less active rats appeared more likely to be killed by ambush predators. Our study supports the hypothesis that a diversity of predator hunting strategies may help maintain trait variation in prey populations.

Florida↗