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At least 901 records · Page 50Linked to original sources
USGS2021

Lampropeltis californiae (California kingsnake) behavior, male-male combat

There are few published descriptions of male-male combat in Lampropeltis spp. under natural conditions. Shaw (1951. Herpetologica 7:149-168) briefly described aggressive interactions between two captive male L. annulata (Mexican Milksnakes) that appeared to be associated with feeding, and Moehn (1967. Copeia 1967:480–481) described the "combat dance" between two male L. calligaster (Prairie Kingsnakes) in the field over a period of 30 minutes, with the snakes "completely intertwined..." and "...in constant motion." Carpenter and Gillingham (1977. Southwest. Nat. 22:517–524) described and illustrated interactions of two male L. holbrooki (Speckled Kingsnake) in a small artificial enclosure. Tabulated categories of male–male combat behaviors in Boid, Colubrid, and Viperid snakes (including Lampropeltis spp.) have been compared in an attempt to relate behavior patterns to phylogenetic relationships (Senter et al. 2014. PLoS ONE 9(9): e107528).

Herpetological Review↗
USGS2026

Assessing hatchery infrastructure for invasive Dreissenid mussel vulnerability in eastern Washington

Zebra ( Dreissena polymorpha ) and quagga ( Dreissena rostriformis bugensis ) mussels have caused the highest economic costs among all aquatic invasive species in the United States (Washington Department of Fish and Wildlife (WDFW) 2016). Officials estimate that if zebra and quagga mussels become established in Washington, removal and management costs could exceed $100 million annually (WDFW 2024a). The Pacific Northwest’s first confirmed detection of quagga mussels occurred in September 2023, when quagga mussel larvae were identified in the Snake River near Twin Falls, Idaho, approximately 280 river kilometers upstream of the Washington border and 680 river kilometers upstream of the Snake-Columbia River confluence (Washington Invasive Species Council 2023). Subsequently, quagga mussel larvae have been detected in Idaho waters at Shoshone Falls Pool, Pillar Falls, and Twin Falls Reservoir located upriver of the Twin Falls hydroelectric facility (Idaho State Department of Agriculture 2024). Additionally, zebra mussels were found in aquarium moss balls at pet stores in Washington in 2021 and 2024. However, neither zebra nor quagga mussels have been detected in Washington’s natural waterways (WDFW 2024b).

Washington↗
USGS1995

Reptiles and amphibians in the endangered longleaf pine ecosystem

The Coastal Plain of the southeastern United States contains a rich diversity of reptiles and amphibians (herpetofauna). Of the 290 species native to the Southeast, 170 (74 amphibians, 96 reptiles) are found within the range of the remnant longleaf pine ( Pinus palustris ) ecosystem (Fig. 1). Many of these species are not found elsewhere, particularly those amphibians that require temporary ponds for reproduction. Many Coastal Plain species are listed federally or by states as endangered or threatened or are candidates for listing (Fig. 1). Examples include the flatwoods salamander ( Ambystoma cingulatum ), striped newt ( Notophthalmus perstriatus ), Carolina and dusky gopher frogs ( Rana capito capito and R.c. sevosa ), eastern indigo snake ( Drymarchon corais couperi ), gopher tortoise ( Gopherus polyphemus), eastern diamondback rattlesnake ( Crotalus adamanteus ), and Florida pine snake ( Pituophis melanoleucus mugitus ).

Book chapter↗
USGS1982

Habitat suitability index models: Cutthroat trout

Cutthroat trout, Salmo clarki, are a polytypic species consisting of several geographically distinct forms with a broad distribution and a great amount of genetic diversity (Hickman 1978; Behnke 1979). Behnke (1979) recognized 13 extant subspecies: Coastal cutthroat (S. c. clarki) in coastal streams from Prince William Sound, Alaska to the Eel Rlver in California; mountain cutthroat (~. ~. alpestris) in upper Columbia and F~Dser River drainages of British Columbia; west slope cutthroat (S. c. lewisi) in the upper Columbia, Salmon, Clearwater, South Saskatchewan and upper Missouri drainages of Montana and Idaho; an undescribed subspecies in the Alvord basin, Oregon; Lahonton cutthroat (S. c ..henshawi), Pauite cutthroat (S. c. seleniris), and an undescribed- subspecies in the Humboldt River drafnage of the Lahontan basin of Nevada and California; Yellowstone cutthroat (S. c. bouvieri) in the Yellowstone drainage of Wyoming and Montana and the Snake River drainage of Wyoming, Idaho, and Nevada; an undescribed subspecies (fine spotted) in the upper Snake River, Wyoming; Bonneville cutthroat (S. c. utah) in the Bonneville basin in Utah, Nevada, Idaho, and Wyoming; Colorado River cutthroat (~. ~. pleuriticus) in the Colorado River drainage in Wyoming, Utah, New Mexico, and Colorado; greenback cutthroat (S. c. stomias) in the South Platte and Arkansas River systems; and Rio Grande cutthroat (~. ~. virginalis) in the Rio Grande River drainage of Colorado and New Mexico. Many of these 13 subspecies are included on Federal or State endangered or threatened species lists. Temperature and chemical preferences, migration, and other ecological and life history attributes vary among cutthroat subspecies (Behnke 1979). Differences in growth rate (Carlander 1969; Scott and Crossman 1973; Behnke 1979) and food preferences have also been reported (Trojnar and Behnke 1974) between some subspecies.

FWS/OBS↗
USGS2016

Evaluating geothermal and hydrogeologic controls on regional groundwater temperature distribution

A one-dimensional (1-D) analytic solution is developed for heat transport through an aquifer system where the vertical temperature profile in the aquifer is nearly uniform. The general anisotropic form of the viscous heat generation term is developed for use in groundwater flow simulations. The 1-D solution is extended to more complex geometries by solving the equation for piece-wise linear or uniform properties and boundary conditions. A moderately complex example, the Eastern Snake River Plain (ESRP), is analyzed to demonstrate the use of the analytic solution for identifying important physical processes. For example, it is shown that viscous heating is variably important and that heat conduction to the land surface is a primary control on the distribution of aquifer and spring temperatures. Use of published values for all aquifer and thermal properties results in a reasonable match between simulated and measured groundwater temperatures over most of the 300 km length of the ESRP, except for geothermal heat flow into the base of the aquifer within 20 km of the Yellowstone hotspot. Previous basal heat flow measurements (∼110 mW/m 2 ) made beneath the ESRP aquifer were collected at distances of >50 km from the Yellowstone Plateau, but a higher basal heat flow of 150 mW/m 2 is required to match groundwater temperatures near the Plateau. The ESRP example demonstrates how the new tool can be used during preliminary analysis of a groundwater system, allowing efficient identification of the important physical processes that must be represented during more-complex 2-D and 3-D simulations of combined groundwater and heat flow.

Idaho↗
USGS2017

Evidence for distributed clockwise rotation of the crust in the northwestern United States from fault geometries and focal mechanisms

Paleomagnetic and GPS data indicate that Washington and Oregon have rotated clockwise for the past 16 Myr. Late Cenozoic and Quaternary fault geometries, seismicity lineaments, and focal mechanisms provide evidence that this rotation is accommodated by north directed thrusting and right-lateral strike-slip faulting in Washington, and SW to W directed normal faulting and right-lateral strike-slip faulting to the east. Several curvilinear NW to NNW trending high-angle strike-slip faults and seismicity lineaments in Washington and NW Oregon define a geologic pole (117.7°W, 47.9°N) of rotation relative to North America. Many faults and focal mechanisms throughout northwestern U.S. and southwestern British Columbia have orientations consistent with this geologic pole as do GPS surface velocities corrected for elastic Cascadia subduction zone coupling. Large Quaternary normal faults radial to the geologic pole, which appear to accommodate crustal rotation via crustal extension, are widespread and can be found along the Lewis and Clark zone in Montana, within the Centennial fault system north of the Snake River Plain in Idaho and Montana, to the west of the Wasatch Front in Utah, and within the northern Basin and Range in Oregon and Nevada. Distributed strike-slip faults are most prominent in western Washington and Oregon and may serve to transfer slip between faults throughout the northwestern U.S.

British Columbia, Oregon, Washington↗
USGS2026

Riverscape heterogeneity shapes population diversity for a migratory fish

Habitat patch dynamics can scale up to influence population demography and diversity with implications for resilience to environmental stochasticity. But how the spatial arrangement and size of habitat patches interact with other components of habitat heterogeneity to shape population diversity at larger spatial scales is not well understood. For riverine fishes, there is increasing evidence that tributary streams provide critical demographic support to main stem rivers. However, the extent to which main stem rivers rely on demographic contributions from tributaries, and the factors underlying this dependence, have not been assessed. Here, we used genetic stock identification to evaluate the effect of tributaries on population diversity of Yellowstone cutthroat trout ( Oncorhynchus virginalis bouvieri ) occupying the main stem Snake River, Wyoming, USA. We found that the main stem relied almost entirely on tributaries for demographic support, but main stem composition varied spatially among river sections. Distance between habitat patches, catchment area, and groundwater availability acted in concert to determine the contribution of specific tributaries to the main stem, but contributions were ultimately modulated by habitat connectivity. We also found evidence for multi-scale spatial structure in tributary contributions, providing insight into untested drivers of main stem river population diversity. Our results demonstrate how spatially discrete and distributed riverscape attributes influence population diversity at broader spatial scales, illustrating how ecosystem resilience emerges from the dynamic, two-way exchange of individuals and energy across habitat networks. Management plans for large rivers that address the ecological contributions of tributaries may be needed to achieve optimal outcomes. Similarly, conservation strategies that exclusively focus on headwater streams may fail to capture the broader habitat requirements necessary to maintain robust cold-water fish populations and associated recreational fisheries, particularly under global environmental change.

Wyoming↗
USGS2019

Genomic pedigree reconstruction identifies predictors of mating and reproductive success in an invasive vertebrate

The persistence of an invasive species is influenced by its reproductive ecology, and a successful control program must operate on this premise. However, the reproductive ecology of invasive species may be enigmatic due to factors that also limit their management, such as cryptic coloration and behavior. We explored the mating and reproductive ecology of the invasive Brown Treesnake (BTS : Boiga irregularis ) by reconstructing a multigenerational genomic pedigree based on 654 single nucleotide polymorphisms for a geographically closed population established in 2004 on Guam ( N = 426). The pedigree allowed annual estimates of individual mating and reproductive success to be inferred for snakes in the study population over a 14‐year period. We then employed generalized linear mixed models to gauge how well phenotypic and genomic data could predict sex‐specific annual mating and reproductive success. Average snout–vent length (SVL), average body condition index (BCI), and trappability were significantly related to annual mating success for males, with average SVL also related to annual mating success for females. Male and female annual reproductive success was positively affected by SVL, BCI, and trappability. Surprisingly, the degree to which individuals were inbred had no effect on annual mating or reproductive success. When juxtaposed with current control methods, these results indicate that baited traps, a common interdiction tool, may target fecund BTS in some regards but not others. Our study emphasizes the importance of reproductive ecology as a focus for improving BTS control and promotes genomic pedigree reconstruction for such an endeavor in this invasive species and others.

Ecology and Evolution↗
USGS2026

Potential causes of shedding aggregations in prairie rattlesnakes

Aggregation is common across taxa and typically confers clear benefits to group members (e.g., allo-parenting, group defense, thermoregulation, access to resources). But aggregation can also be costly. The mechanisms that underpin aggregation—and the cues that elicit it—inform our understanding of how animals resolve tradeoffs among selection pressures. Snakes sometimes form conspicuous aggregations associated with hibernation, gestation, or parturition. Aggregation during ecdysis has also been described in some species, but infrequent observations and the synchronicity of ecdysis have confounded attempts to deduce the mechanism(s) responsible for the behavior. We documented aggregation during ecdysis in a population of asynchronously shedding prairie rattlesnakes ( Crotalus viridis ) and tested predictions generated from four hypotheses proposed to explain this behavior. We found that individuals undergoing ecdysis were more likely to aggregate. Our data did not support the hypothesis that rattlesnakes aggregate to improve their thermal efficiency, but we found some support for the reproductive facilitation and thermal landscape hypotheses as possible explanations for aggregation during ecdysis.

Wyoming↗
USGS2022

Fijian sea krait behavior relates to fine-scale environmental heterogeneity in old-growth coastal forest: The importance of integrated land–sea management for protecting amphibious animals

The importance of terrestrial coastal ecosystems for maintaining healthy coral reef ecosystems remains understudied. Sea kraits are amphibious snakes that require healthy coral reefs for foraging, but little is known about their requirements of terrestrial habitats, where they slough their skin, digest prey, and breed. Using concurrent microclimate measurements and behavior surveys, we show that a small, topographically flat atoll in Fiji with coastal forest provides many microhabitats that relate to the behaviors of Yellow Lipped Sea Kraits, Laticauda colubrina . Microclimates were significantly related to canopy cover, leaf litter depth, and distance from the high-water mark (HWM). Sea kraits were almost exclusively observed in coastal forest within 30 m of the HWM. Sloughing of skins only occurred within crevices of mature or dying trees. Resting L. colubrina were significantly more likely to occur at locations with higher mean diurnal temperatures, lower leaf litter depths, and shorter distances from the HWM. On Leleuvia, behavior of L. colubrina therefore relates to environmental heterogeneity created by old-growth coastal forests, particularly canopy cover and crevices in mature and dead tree trunks. The importance of healthy coastal habitats, both terrestrial and marine, for L. colubrina suggests it could be a good flagship species for advocating integrated land-sea management. Furthermore, our study highlights the importance of coastal forests and topographically flat atolls for biodiversity conservation. Effective conservation management of amphibious species that utilize land- and seascapes is therefore likely to require a holistic approach that incorporates connectivity among ecosystems and environmental heterogeneity at all relevant scales.

Ecology and Evolution↗
USGS2021

Spatial ecology of invasive Burmese pythons in southwestern Florida

Understanding the spatial ecology of an invasive species is critical for designing effective control programs. Determining and quantifying home range estimates and habitat associations can streamline targeted removal efforts for wide-ranging, cryptic animals. The Burmese python ( Python bivittatus ) is a large-bodied constrictor snake with an established and expanding invasive population in southern Florida. This apex predator has severely impacted native wildlife across the Greater Everglades ecosystem. However, limited ecological information exists on this invasive species at the landscape level. Here, we present results from a study using radiotelemetry to quantify movements and habitat use patterns of 25 adult Burmese pythons in southwestern Florida, USA, for average periods of 814 d (range: 288–1809). Our objective was to quantify home range size, movement rates, and second- and third-order habitat selection. Mean annual home range size was 7.5 km 2 ± 2.9 km 2 (95% kernel density estimate), and pythons moved at a maximum mean daily rate of 0.52 km/d. Burmese pythons selected agriculture, freshwater wetland, saline wetland, and upland land cover classes but avoided open water and urban land cover classes. Nest site selection was highest for pythons at an elevation of 1.7 m with nesting hotspots concentrated on the borders of urban and agricultural areas or in sandy forested upland habitats. A broader understanding of the spatial utilization of Burmese pythons will enhance the utility of emerging control strategies across their invaded range.

Florida↗
USGS2016

Removing sun glint from optical remote sensing images of shallow rivers

Sun glint is the specular reflection of light from the water surface, which often causes unusually bright pixel values that can dominate fluvial remote sensing imagery and obscure the water-leaving radiance signal of interest for mapping bathymetry, bottom type, or water column optical characteristics. Although sun glint is ubiquitous in fluvial remote sensing imagery, river-specific methods for removing sun glint are not yet available. We show that existing sun glint-removal methods developed for multispectral images of marine shallow water environments over-correct shallow portions of fluvial remote sensing imagery resulting in regions of unreliable data along channel margins. We build on existing marine glint-removal methods to develop a river-specific technique that removes sun glint from shallow areas of the channel without overcorrection by accounting for non-negligible water-leaving near-infrared radiance. This new sun glint-removal method can improve the accuracy of spectrally-based depth retrieval in cases where sun glint dominates the at-sensor radiance. For an example image of the gravel-bed Snake River, Wyoming, USA, observed-vs.-predicted R 2 values for depth retrieval improved from 0.66 to 0.76 following sun glint removal. The methodology presented here is straightforward to implement and could be incorporated into image processing workflows for multispectral images that include a near-infrared band.

Earth Surface Processes and Landforms↗
USGS2019

Demographic factors affecting population growth in giant gartersnakes

Demographic models provide insight into which vital rates and life stages contribute most to population growth. Integral projection models (IPMs) offer flexibility in matching model structure to a species’ demography. For many rare species, data are lacking for key vital rates, and uncertainty might dissuade researchers from attempting to build a demographic model. We present work that highlights how the implications of uncertainties and unknowns can be explored by building and analyzing alternative models. We constructed IPMs for the threatened giant gartersnake ( Thamnophis gigas ) based on published studies to determine where management efforts could be targeted to have the greatest effect on population persistence and what unknowns remain for future research. Given uncertainty in the survival of snakes during their first year, and in the form of the size‐survival relationship, we modeled a range of scenarios and evaluated where models agree about factors influencing population growth and where discrepancies exist. For most scenarios, the survival of large adult females had the greatest influence on population growth, but the relative importance of juvenile versus adult somatic growth for population growth was dependent on the recruitment probability and the shape of the size‐survival function. More data on temporal variation and covariance among vital rates would improve stochastic models for the giant gartersnake. This paper demonstrates the effectiveness of IPMs for studying the demography of reptiles and the value of the model‐building process for formalizing what is known and unknown about the demography of rare species. Published 2019. This article is a U.S. Government work and is in the public domain in the USA.

California↗
USGS2023

Bobcat occupancy, tree islands, and invasive Burmese pythons in an Everglades conservation area

Bobcats ( Lynx rufus ) are terrestrial mammals that also inhabit tree islands (i.e., topographically elevated patches of forested land) embedded in the subtropical Everglades wetlands, which serve as a dry refuge habitat during the wet season in this region of Florida, USA. The Comprehensive Everglades Restoration Plan seeks to restore Everglades water flow to pre-drainage conditions, but little is known about how water levels or other landscape-level factors may influence mammalian occurrence, such as bobcats, on the tree islands in this ecosystem. We used game camera records and occupancy modeling to test for effects of static habitat variables and dynamic hydrologic variables. We hypothesized that deep water levels would limit the accessibility of tree islands to bobcats; therefore, we predicted that bobcat occupancy would decline with higher water levels. We also tested for the effect of an expanding invasive snake (i.e., Burmese python [ Python molarus bivittatus ]) using output from a model constructed to predict density and spread of Burmese pythons across southern Florida. We hypothesized that increases in Burmese pythons on the landscape would influence the food resources of bobcats, resulting in reduced bobcat occupancy at higher predicted densities of pythons. We built detection histories using 1,855 bobcat images from game cameras set on 87 tree islands in an Everglades conservation area from 2005–2019. Bobcat occupancy was significantly diminished when predicted Burmese python densities exceeded approximately 3 Burmese pythons/km 2 . Bobcat occupancy probability also increased with tree-island density around the focal tree island. Although water depth and hydroperiod surrounding tree islands appeared in our top 3 candidate models, the hydrologic variables had weak effects on bobcat occupancy. Our results suggest that while hydrologic dynamics may play a role, the invasive Burmese python has stronger influences on bobcat occupancy of tree islands in this Everglades conservation area.

Florida↗
USGS2023

Drawdown, habitat, and kokanee populations in a western U.S. reservoir

Greater drought frequency and severity due to climate change will result in greater drawdown of water storage reservoirs. However, changes to oxythermal regimes due to drawdown are reservoir specific and interface with fish species-specific habitat requirements, producing varying effects on coldwater fish populations. We examined the effect of drawdown on the oxythermal habitat and relative abundance of kokanee Oncorhynchus nerka , a coldwater salmonid, in Island Park Reservoir on the Henrys Fork of the Snake River, Idaho. A measure of relative kokanee abundance was negatively, exponentially related to drawdown. Oxythermal patterns measured in the reservoir during 2021, a severe drought year, revealed that drawdown reduced kokanee habitat by increasing water temperatures and decreasing dissolved oxygen concentrations. Oxythermal refugia for kokanee appeared to relate to inflow from the spring-fed Henrys Fork and other groundwater inflows. However, we did not quantify groundwater flow or connections, and we did not study kokanee population demographics or mortality. Reducing these sources of uncertainty is a priority for future study. Still, our study highlights a potential mechanism connecting reservoir drawdown to fish populations and the unique yet predictable mechanisms by which reservoir drawdown interacts with reservoir morphometry to affect fish habitat availability.

Idaho↗
USGS2005

Application of wavelet analysis for monitoring the hydrologic effects of dam operation: Glen canyon dam and the Colorado River at lees ferry, Arizona

Wavelet analysis is a powerful tool with which to analyse the hydrologic effects of dam construction and operation on river systems. Using continuous records of instantaneous discharge from the Lees Ferry gauging station and records of daily mean discharge from upstream tributaries, we conducted wavelet analyses of the hydrologic structure of the Colorado River in Grand Canyon. The wavelet power spectrum (WPS) of daily mean discharge provided a highly compressed and integrative picture of the post-dam elimination of pronounced annual and sub-annual flow features. The WPS of the continuous record showed the influence of diurnal and weekly power generation cycles, shifts in discharge management, and the 1996 experimental flood in the post-dam period. Normalization of the WPS by local wavelet spectra revealed the fine structure of modulation in discharge scale and amplitude and provides an extremely efficient tool with which to assess the relationships among hydrologic cycles and ecological and geomorphic systems. We extended our analysis to sections of the Snake River and showed how wavelet analysis can be used as a data mining technique. The wavelet approach is an especially promising tool with which to assess dam operation in less well-studied regions and to evaluate management attempts to reconstruct desired flow characteristics. Copyright ?? 2005 John Wiley & Sons, Ltd.

River Research and Applications↗
USGS2023

Survey optimization for invasive Burmese pythons informed by camera traps

The Burmese python ( Python bivittatus ) is an invasive predator responsible for broad mammal declines in South Florida, United States. Despite their large size, pythons remain cryptic and require multifaceted approaches for detection. We evaluated a novel technique by deploying camera traps at known locations of radiotagged pythons in the Florida Keys. We estimated daily detection probabilities of snakes and plotted diel activity patterns. Our results suggest camera traps can effectively survey pythons but seasonality and camera trigger mechanisms affect utility. Pythons were most detectable with time-lapse camera traps and more detectable in winter. The diel activity pattern of pythons peaked midday through early afternoon, indicating an optimal survey time for other search methods. Artificial intelligence can alleviate photo volume, so we recommend a combination of motion detection and time-lapse with shorter time (1 min) intervals for python-specific surveys and where camera traps are deployed to monitor mammals to improve passive python detection.

Florida↗
USGS2025

Observability of eastern massasauga (Sistrurus catenatus) during visual encounter surveys in Michigan, USA

Visual encounter surveys are commonly used to document site occupancy for the eastern massasauga ( Sistrurus catenatus ; EMR). Efficacy of surveys depends on visual and auditory cues, with basking behavior and burrow use strongly affecting detection. Our goal was to predict body exposure and probability of burrow use from telemetered EMR to better inform implementation of visual encounter surveys. We collected body exposure and burrow use from 23 EMR (14 females [12 gravid], 9 males) from April through September (i.e., active season) at 2 sites in south central Michigan, USA, 2020–2022. Average body exposure for observed snakes was 42% (SE = 3%) and ranged from 0–100%. Percent body exposure during the active season was positively influenced by air temperature, where body exposure increased from ~25% at ~15°C to ~50% at ~35°C. We did not find an effect of cloud cover, hour of day, humidity, or sex on EMR body exposure. Of 176 observations of EMR during the active season, we found EMR using burrows 20 times (~11% of observations). Julian date and air temperature affected the probability of EMR burrow use early in the active season. Probability of EMR burrow use was <0.10 from the end of May through the end of October and was almost 0.00 after mid-July. The probability of using a burrow was generally low (i.e., <0.25) across the range of air temperatures measured in our study, but approached 0.00 as temperatures exceeded 30°C. We did not find an effect of cloud cover, time of day, humidity, or sex on probability of EMR burrow use. Our results indicated that EMR observability in southern Michigan was greatest when air temperatures were 30°C to 35°C, corresponding to when EMR were visible and aboveground.

Michigan↗