USGS Science⌕ Search

SEARCH · USGS Science

Results for “Biological Conservation,”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 793 records · Page 44Linked to original sources
USGS2018

Long-term spotlight surveys of American alligators in Mississippi, USA

Accurate population estimates and assessments of trajectory are an essential part of harvest management for game species and conservation action plans for protected species. Long-term monitoring can lead to ecological understanding by identifying biotic and abiotic drivers of population dynamics. Spotlight surveys are a widely used method to monitor abundance and size-class structure of crocodilian populations. The American Alligator (Alligator mississippiensis) has recovered from significant population reductions in the southeastern United States. The Mississippi Department of Wildlife, Fisheries, and Parks (MDWFP) has conducted alligator spotlight surveys since 1971 to monitor populations. We analyzed this long-term alligator survey dataset to assess possible trends in counts as a proxy for potential population changes. We tested for a positive trend in count data over 46 y and evaluated covariates that could influence counts to assist future survey protocols. Alligator counts during 1971– 2016 increased across survey routes in Mississippi. This observed positive response may represent an increase of the alligator population in Mississippi as a result of conservation benefits accrued from improved wetland conditions and species-specific management policies. Evaluation of survey covariates indicated recent rainfall and increasing wind velocity had negative effects on alligator counts while increasing water temperature had a positive effect. Implementing robust survey techniques will improve the reliability of alligator monitoring data and their application to the management of alligator populations. Further, these improved approaches may be useful to other conservation and management agencies as well as for other crocodilian species.

Mississippi↗
USGS2009

Efficacy of automatic vocalization recognition software for anuran monitoring

Surveys of vocalizations are a widely used method for monitoring anurans, but it can be difficult to coordinate standardized data collection across a large geographic area. Digital automated recording systems (ARS) offer a low-cost method for obtaining samples of anuran vocalizations, but the number of recordings can easily overwhelm human listeners. We tested Song Scope, an automatic vocalization recognition software program for personal computers to determine if this type of machine learning approach is currently a viable solution for anuran monitoring. For three species, Song Scope scanned more than 200 h of recordings in 3-20 h at the settings we chose. The software misidentified true calls (false positive) at rates of 2.7%-15.8% per species and failed to detect calls (false negative) in 45%-51% of recordings. There exists a tradeoff between false positive and false negative errors, which can be adjusted by setting the minimum criteria for the recognition software. Users of this approach should carefully consider their reasons for monitoring and how they intend to use the data before creating a large monitoring network.

Louisiana↗
USGS2020

Conservation genetics of imperiled striped whipsnake in Washington

Conservation of wide-ranging species is aided by population genetic information that provides insights into adaptive potential, population size, interpopulation connectivity, and even extinction risk in portions of a species range. The Striped Whipsnake (Masticophis taeniatus) occurs across 11 western U.S. states and into Mexico but has experienced population declines in parts of its range, particularly in the state of Washington. We analyzed nuclear and mitochondrial DNA extracted from 192 shed skins, 63 muscle tissue samples, and one mouth swab to assess local genetic diversity and differentiation within and between the last known whipsnake populations in Washington. We then placed that information in a regional context to better understand levels of differentiation and diversity among whipsnake populations in the northwestern portion of the range of the species. Microsatellite data analyses indicated that there was comparable genetic diversity between the two extant Washington populations, but gene flow may be somewhat limited. We found moderate to high levels of genetic differentiation among states across all markers, including five microsatellites, two nuclear genes, and two mitochondrial genes. Pairwise state-level comparisons and dendrograms suggested that Washington whipsnakes are most closely related to those in Oregon, and distinct from Idaho, Nevada, and Utah, approximately following an isolation by distance model. We conclude that Washington populations of whipsnakes have experienced recent isolating events, but they have yet to lose genetic diversity. The longevity and high vagility of the species may provide opportunity for conservation of whipsnakes in the state as long as shrubland habitat is available

Washington↗
USGS2020

Environmental contamination and unusual snake mortality in an urban national wildlife refuge

The National Wildlife Refuge (NWR) System protects ~150 million acres of land and water in the United States and provides habitat for >2,000 native vertebrates species. Although legally protected, wildlife populations within these refuges can be threatened by anthropogenic activities. The lack of knowledge about such threats has the potential to undermine biodiversity conservation. We investigated patterns of wildlife mortality among three NWRs in the northern U.S. Gulf Coast. Visual surveys (958 total search-hours) were conducted for live or dead amphibians and reptiles at Big Branch, Bogue Chitto, and Bayou Sauvage NWRs. An exceptionally high incidence of snake mortality (>800% above background, P < 0.001) was observed at one site (Haul Road, Bayou Sauvage NWR). Mortality affected seven species and recurred for 29 months. Intact carcasses were subject to histopathological examination and diagnostic testing. Cause of death was undetermined (n = 9) or attributed to various pathogens (n = 5). To investigate possible underlying causes of this unusual mortality, water exposure challenges and soil toxicological analyses (n = 6 and 11 sites, respectively) were conducted on samples from Bayou Sauvage NWR, given the known potential for anthropogenic contamination in the refuge. In a controlled experiment, survival of Anaxyrus fowlerii embryos exposed to water from Recovery Road (i.e., 250m from a landfill) and Haul Road was reduced 92% and 48%, respectively, compared to four reference sites in the refuge. Sediment analyses suggested at least seven distinct sources of contaminants in Bayou Sauvage NWR. Potential sources included a landfill, illegal dumping, vehicle emissions, pesticide migration, and an active hydrocarbon pipeline leak discovered 600 m from Haul Road. Synthesis and applications: Although further research is needed to determine whether the observed mortality and contamination are related, these collective findings suggest that anthropogenic factors may threaten the ecological integrity of one of the United States largest urban wildlife refuges. More broadly, our study highlights the critical need for species inventories, baseline data, and systematic monitoring in NWRs. Such information is essential to detecting and mitigating anthropogenic threats to biodiversity conservation in protected areas.

Louisiana↗
USGS2021

Widespread Ranavirus and Perkinsea infections in Cuban treefrogs (Osteopilus septentrionalis) invading New Orleans, USA

Invasive species can negatively impact ecosystems in numerous ways, including vectoring pathogenic organisms. In amphibians, a lineage globally threatened by multiple pathogens, this spread of disease via invasive species could contribute to declines in native populations. The Cuban Treefrog (Osteopilus septentrionalis) is invasive in the southeastern USA. To assess whether O. septentrionalis is a potential reservoir host for the pathogens Batrachochytrium dendrobatidis (Bd; Amphibian Chytrid Fungus), Ranavirus (Rv), and Perkinsea (Pr), we sampled 82 individuals from a recently invaded site in New Orleans, Louisiana, USA. We used quantitative PCR to assess prevalence and intensity of Bd, Rv, and Pr in mouthparts and tail clips from 22 larvae and in toe clips from 60 metamorphosed frogs. We compared infection prevalence and intensity across host characteristics, including Fulton’s Body Condition, sex, and life stage. None of the individuals were infected with Bd, 72% were infected with Rv, and 44% were infected with Pr. Twenty-three individuals (28%) were co-infected with Rv and Pr, but co-infection did not significantly predict the prevalence or intensity of either Rv or Pr. Although we did not observe any disease signs, Pr infections were significantly associated with lower body condition, suggesting sub-lethal fitness costs. Our study establishes that invasive O. septentrionalis in New Orleans are infected with two pathogens of global concern for amphibians. Understanding host-pathogen dynamics in O. septentrionalis in Louisiana is a critical step towards understanding how this invasive species could threaten amphibian biodiversity in the region by transmitting infectious pathogens.

Louisiana↗
USGS2018

Comparing growth and body condition of indoor-reared, outdoor-reared, and direct-released juvenile Mojave desert tortoises

Desert tortoise populations have declined, and head-starting hatchlings in captivity until they are larger and older — and presumably more likely to survive — is one strategy being evaluated for species recovery. Previous studies have reared hatchlings in outdoor, predator-proof pens for 5–9 years before release, in efforts to produce hatchlings in excess of 100–110 mm midline carapace length that are believed to be predation-resistant. We began a comparative study to evaluate indoor-rearing to shorten this rearing period by facilitating faster initial growth. We assigned 70 neonates from the 2015 hatching season to three treatment groups: 1) indoor-reared (n = 30), 2) outdoor-reared (n = 20), and 3) direct-release (n = 20). Direct-release hatchlings were released shortly after hatching in September 2015 and monitored 1–2x per week with radio telemetry. We head-started the indoor- and outdoor-reared treatment groups for 7 mo before releasing them in April 2016. Indoor-reared tortoises were fed 5x per week (Sep–Mar). Outdoor-reared tortoises had access to native forage and were given supplemental water and food once per week while active before winter dormancy. Indoor-reared tortoises grew >16x faster than direct-release tortoises and >8x faster than outdoor-reared tortoises. However, indoor-reared tortoises weighed less and had softer shells than comparatively sized older (3–4 year-old) tortoises raised outdoors. Increasing the duration of the indoor-rearing period or incorporating a combination of both indoor and later outdoor husbandry may increase shell hardness among head-starts, while retaining the growth-promoting effect of indoor rearing and shortening overall captivity duration.

California↗
USGS2020

Comparing husbandry techniques for optimal head-starting of the Mojave desert tortoise (Gopherus agassizii)

Mojave Desert Tortoise ( Gopherus agassizii ) populations continue to decline throughout their range. Head-starting—the captive rearing of offspring to a size where they are presumably more likely to survive post-release—is being explored as a potential recovery tool. Previous Desert Tortoise head-starting programs have reared neonates exclusively outdoors. Here, we explore using a combination of indoor and outdoor captive rearing to maximize post-release success and rearing efficiency. We assigned 68 neonates (2016 cohort) to one of two treatments: Outdoor HS (n = 38), where neonates were reared exclusively in outdoor predator-proof enclosures, and Combo HS (n = 30), where neonates were reared indoors for 1 y followed by outdoor rearing for 1 y. After 2 y of captive rearing, we randomly selected 24 Outdoor HS and 24 Combo HS juveniles for release in the Mojave National Preserve, CA on 25 September 2018. We compare pre-release size, body condition, and shell hardness as well as first year post-release movement and survival between the treatment groups. Pre-release body condition was not significantly different between groups. Outdoor HS tortoises, however, were significantly smaller and had significantly softer shells than Combo HS tortoises. Excluding two missing animals, released head-starts experienced 78.2% survival through their first year after release. Combo HS tortoises on average dispersed significantly shorter distances after 1 y than Outdoor HS animals. Our findings that Combo HS animals were larger and had harder shells at release, and exhibited high survival but low dispersal following release, support the implementation of combination head-starting as part of the recovery effort for the Mojave Desert Tortoise.

California↗
USGS2020

Efficacy and biases of cover object survey design for sampling eastern red-backed salamanders (Plethodon cinereus) at forest edge and interior locations

Terrestrial salamanders are adapted to moist, cool microenvironments that facilitate cutaneous respiration and decrease risk of desiccation. Warmer, drier microenvironments may induce habitat use changes by salamanders to alleviate stressful microenvironmental conditions. Changes in salamander habitat use may bias population metrics when sampling occurs in areas with different microenvironmental conditions. The objective of this study was to determine whether Plethodon cinereus (Eastern Red-backed Salamander) exhibit surface cover object refugia preferences or occupancy rate differences at sampling locations with different microenvironmental conditions and with respect to sampling day of year. We assessed P. cinereus occupancy rates and preference of surface cover refugia using artificial and natural cover objects in two sampling locations: forests along rights-of-way (EDGEFOR) and interior forests (INTFOR). Plethodon cinereus showed no preference for cover object type (coverboards, logs, and rocks) in either EDGEFOR or INTFOR sampling plots. Occupancy rates were greater under cover objects in INTFOR plots than EDGEFOR plots. Occupancy rates increased with increasing cover object width and decreased with day of year (spring-late summer) irrespective of cover object type or sampling location. Our study suggests that incorporating multiple cover object types into study designs will not incur bias resulting from preference of P. cinereus for cover objects.

West Virginia↗
USGS2022

Factors influencing the use of water-filled tree cavities by eastern ratsnakes (Pantherophis alleghaniensis)

For some animals, specific microhabitats may be particularly important for certain behaviors and/or age or sex classes. Here we explore the use of previously unrecognized retreat sites (water-filled tree cavities) by Eastern Ratsnakes ( Pantherophis alleghaniensis ). During 4 y of radio telemetry, approximately half of the 45 ratsnakes monitored used water-filled cavities. Typically, water-filled cavities (phytotelmata) were in live Laurel Oaks ( Quercus laurifolia ) and Black Cherry ( Prunus serotina ) where limbs had broken off, internal wood had rotted, and water accumulated. Water-filled cavities were used by ratsnakes at about the same frequency as tree stumps but less frequently than snags, brushpiles, or downed logs. Snakes remained in water-filled cavities for an average of 10 d compared to only 2–4 d in other structures. Reproductive females (both pre- and post-egg laying) were four times more likely to use water-filled cavities than non-gravid or male ratsnakes, suggesting cavities are used to offset water loss associated with gestation. Ratsnakes used water-filled cavities far more in summer than spring even though thermal profiles of cavities were similar to those of other retreat structures, indicating their use was not for thermoregulation. Multiple snakes often used cavities simultaneously, suggesting that cavities are either limited or facilitate social interaction. Snakes did not use artificial water-filled cavities, suggesting that natural sites may provide snakes with some unknown benefit beyond hydration. Water-filled cavities appear to be important for ratsnakes, particularly reproductive females, and warrant further investigation.

South Carolina↗
USGS2021

Evaluating hydrophones for detecting underwater-calling frogs

Amphibians are declining and disappearing worldwide at an alarming rate, emphasizing the need for accurate surveys to document the distribution and abundance of this imperiled taxon. Automated recorders are a powerful tool for surveyors to continuously monitor for calling amphibians. However, we are discovering that many species of frog call when submerged underwater making it challenging if not impossible for terrestrial observers to use microphones to detect them. Here, we conducted two field experiments to assess the efficacy of hydrophones for detecting underwater frog calls. The first was designed to directly compare detection probability of underwear frog calls by hydrophones, microphones, and human observers. The second was to evaluate the wetland characteristics that most influenced the detection distance of hydrophones. We found that hydrophones were 30 times more likely to detect underwater calls relative to microphones and 8.5 times more likely relative to human observers. Hydrophones detected underwater frog calls emitted 65 m away and performed best when water was deep (> 50 cm) and there were few submerged obstacles (i.e. logs) present. Hydrophones may be an important tool for herpetologists to survey for a suite of frog species known to vocalize underwater and as more practitioners use hydrophones the list of underwater-calling frogs is certain to grow.

New York↗
USGS2021

An updated assessment of status and trend in the distribution of the Cascades frog (Rana cascadae) in Oregon, USA

Conservation efforts need reliable information concerning the status of a species and their trends to help identify which species are in most need of assistance. We completed a comparative evaluation of the occurrence of breeding for Cascades Frog ( Rana cascadae ), an amphibian that is being considered for federal protection under the U.S. Endangered Species Act. Specifically, in 2018–2019 we resurveyed 67 sites that were surveyed approximately 15 y prior and fit occupancy models to quantify the distribution of R. cascadae breeding in the Cascade Range, Oregon, USA. Furthermore, we conducted a simulation exercise to assess the power of sampling designs to detect declines in R. cascadae breeding at these sites. Our analysis of field data combined with our simulation results suggests that if there was a decline in the proportion of sites used for R. cascadae breeding in Oregon, it was likely a < 20% decline across our study period. Our results confirm that while R. cascadae detection probabilities are high, methods that allow the sampling process to be explicitly modeled are necessary to reliably track the status of the species. This study demonstrates the usefulness of investing in baseline information and data quality standards to increase capacity to make similar comparisons for other species in a timeframe that meet the needs of land managers and policy makers.

Oregon↗
USGS2024

Hiding in plain sight: Federally protected Ringed Map Turtles (Graptemys oculifera) found in a new river system

Understanding the geographical range of a species is essential to successful conservation and management, but their ranges are not always fully known. Ringed Map Turtles (Graptemys oculifera) have been federally listed as a Threatened species since 1986, and they have long been considered endemic to the Pearl River system of central Mississippi and southeastern Louisiana, USA. Based on a 2021 citizen scientist observation, a new G. oculifera population was discovered in the Bogue Falaya, a river system that is west of and isolated from the Pearl River system. Genetic analyses of 23 individuals from the Bogue Falaya demonstrate their genetic distinctiveness relative to sites in the Pearl River, suggesting it is a natural rather than introduced population. Therefore, G. oculifera should no longer be considered endemic to the Pearl River system, and this Bogue Falaya population of G. oculifera may warrant the designation of a distinct population segment under the U.S. Endangered Species Act. A thorough assessment of the distribution, abundance, and conservation threats to the Bogue Falaya population of G. oculifera as well as surveys of surrounding systems could help to inform future management actions. This discovery of a long-time federally protected species in the city limits of Covington, Louisiana, documents how citizen scientists can advance scientific knowledge.

Louisiana↗
USGS2023

Eastern Indigo snake (Drymarchon couperi) shelter site use In peninsular Florida, USA, and implicatIons for habItat conservatIon

Shelters are critical for many species as protection from predators and extreme temperatures. Successful conservation of reptiles requires understanding both shelter site requirements and availability. The Eastern Indigo Snake (EIS; Drymarchon couperi ) is endemic to the southeastern U.S. and is federally listed. Recovery has focused on maximizing unfragmented landscapes, with less attention on fine-scale features such as shelter sites. In the northern EIS range, Gopher Tortoise ( Gopherus polyphemus ) burrows are used extensively for shelter. Although EIS in peninsular Florida often shelter in tortoise burrows, they also use other shelters where tortoise burrows are scarce or absent. Solely focusing EIS survey and management efforts where Gopher Tortoises are present may overlook occupied habitats and misallocate resources. We investigated the importance of different shelter sites in central Florida using data from radio-tracked EIS. We modeled the use of shelter categories as a function of sex, season, and habitat using Bayesian multinomial Generalized Linear Models. Results showed that EIS in peninsular Florida used Gopher Tortoise burrows across all seasons and habitats. Tortoise burrow use was highest in xeric habitats and lowest in mesic habitats where burrows are most and least abundant, respectively. There was less variability in shelter site use in disturbed habitats and flatwoods. Tortoise burrow use by EIS in the cool season across sexes and habitats in our study was much lower than in southern Georgia. Our results indicate that EIS are less dependent on Gopher Tortoise burrows in peninsular Florida and that suitable habitats with few or no tortoise burrows could still provide conservation value for EIS.

Florida, Georgia↗
USGS2025

Experimental evaluation of Eastern box turtle (Terrapene carolina carolina) detectability in visual search surveys

Understanding how detection probability varies over time, space, or in response to measurable covariates is important to inform the monitoring and assessment of many species. A standard model to understand detectability, the availability/perception model, admits that detection probability is the composite of two components: availability and ability of surveyors to detect the target. Availability is largely affected by environmental and behavioral factors, whereas perception is primarily affected by attributes of individual observers and survey protocols, and thus can potentially be partially controlled by survey design. We designed and implemented a field study to understand the perception component of detection for Eastern Box Turtles ( Terrapene carolina carolina ) using visual encounter surveys. We obtained and deployed museum specimens of Eastern Box Turtle shells and subjected them to visual search surveys by observers in realistic field situations. Overall, about 50% of the box turtle shells were detected by observers, including 41.5% in what we categorized as partially visible and 63.0% as fully visible. There were significant differences among observers, which may be due to observer-specific variation in search technique; the observers varied in how well they achieved the protocol guidance. Therefore, in visual search surveys, care in study design and analysis should be taken to account for variation in perception to determine detectability, as our study suggests 37% of perceptible targets are missed by surveyors.

Maryland↗
USGS2026

Line transect distance sampling and genetic analyses reveal a small but genetically diverse coastal Gopher Tortoise (Gopherus polyphemus) population

Gopher Tortoises inhabit coastal systems, including barrier islands, across the southeastern U.S. St. Vincent National Wildlife Refuge is an uninhabited barrier island located off the coast of northwestern Florida. Although tortoises have been observed on the island, no information is available on the status of the population. We conducted a line transect distance sampling survey to evaluate the Gopher Tortoise population on St. Vincent Island. Additionally, we collected samples for genetic analyses from 11 individual tortoises captured opportunistically and via bucket traps on the island and 15 tortoises captured at nearby mainland sites. Surveys covered approximately 43% of the sampling frame and resulted in 55 burrows, 28 of which were occupied. The abundance estimate for the island was 52 tortoises (95% confidence interval [CI] = 27–100) and the density was relatively low at 0.071 tortoises/ha (95% CI = 0.037–0.136). Genetic analyses of two mtDNA markers identified a new haplotype unique to St. Vincent Island and another three haplotypes previously found across the southeastern U.S. The genetic composition of Gopher Tortoises on St. Vincent Island is representative of the entire southeastern U.S. but most closely aligns with tortoise populations east of the Apalachicola-Chattahoochee River system. Although the tortoise population on this island is small, the extent of seemingly appropriate habitat on the island and the genetic diversity of the population suggests the potential for growth with added management intervention.

Florida↗
USGS2026

Amphibian use of recently created wetlands in the Palouse region of northern Idaho, USA

Human development has resulted in the loss of natural wetlands in many regions and thus has led to amphibian habitat loss. Human-constructed wetlands are increasingly prevalent, particularly in human-modified landscapes, and can be used as breeding habitats by amphibians. It is important to identify factors influencing amphibian use of constructed wetlands to guide future wetland creation efforts. We examined wetland- and landscape-level factors influencing the presence and reproduction of native amphibians in 33 recently created (2–11 yold) wetlands within an urban-agricultural interface in northern Idaho, USA. We recorded wetland age, perimeter vegetation, and percentage of surrounding land cover as covariates and modeled detection and occupancy using Bayesian Multi-scale Occupancy Models for the three species we detected: Sierran Treefrog ( Pseudacris sierra ), Colombia Spotted Frog ( Rana luteiventris ), and Long-Toed Salamander ( Ambystoma macrodactylum ). Our results indicate that these three species can rapidly colonize recently created wetlands in an urban-agricultural interface. The effects of wetland- and landscape-scale features varied across species. Colombia Spotted Frog occupancy was greatest in older wetlands with some evidence for a negative association with more urbanized landscapes. Long Toed Salamanders and Sierran Treefrogs were not associated with wetland age but also showed some evidence of negative associations with urbanization. Long-Toed Salamanders showed evidence of using less vegetated wetlands while Sierran Treefrogs showed evidence of using more vegetated wetlands. Our results are consistent with multiple studies showing that wetlands in human-modified landscapes can provide amphibian breeding habitat, and they suggest that including vegetation plantings within recently created wetlands may promote amphibian colonization. Anecdotal observations also indicate that designing wetlands with sufficient hydroperiod for metamorphoses may be important for ensuring that newly created wetlands benefit amphibian populations.

Idaho↗
USGS2013

Adventures on the roof of the world

T o conduct field biology requires tenacity, grit, and flexibility; to endeavor to achieve conservation success requires patience, persistence, and passion. The essence of field biology and the hope for conservation success are both reflected admirably in George B. Schaller's most recent book, Tibet Wild: A Naturalist's Journeys on the Roof of the World . I can think of no living biologist who embodies these characteristics more than Schaller does. Nearly 80 years old, he still regularly treks in faraway lands, observing and recording the natural history of species that the vast majority of us will never see in the wild. Schaller is a vanguard, and Tibet Wild , like his other books, is a sentinel of urgent conservation need.

BioScience↗
USGS2010

Global research priorities for sea turtles: Informing management and conservation in the 21st century

Over the past 3 decades, the status of sea turtles and the need for their protection to aid population recovery have increasingly captured the interest of government agencies, non-governmental organisations (NGOs) and the general public worldwide. This interest has been matched by increased research attention, focusing on a wide variety of topics relating to sea turtle biology and ecology, together with the interrelations of sea turtles with the physical and natural environments. Although sea turtles have been better studied than most other marine fauna, management actions and their evaluation are often hindered by the lack of data on turtle biology, human–turtle interactions, turtle population status and threats. In an effort to inform effective sea turtle conservation a list of priority research questions was assembled based on the opinions of 35 sea turtle researchers from 13 nations working in fields related to turtle biology and/or conservation. The combined experience of the contributing researchers spanned the globe as well as many relevant disciplines involved in conservation research. An initial list of more than 200 questions gathered from respondents was condensed into 20 metaquestions and classified under 5 categories: reproductive biology, biogeography, population ecology, threats and conservation strategies.

Endangered Species Research↗