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At least 19 recordsLinked to original sources
USGS2026

Recent range expansion and documentation of a reproductive population of northern snakehead Channa argus (Cantor, 1842) in the Saint Francis River Drainage, Missouri

Northern snakehead Channa argus (Cantor, 1842) is an aquatic invasive fish species in the United States with first documented occurrence in the wild in the 2000s. Management efforts to control their populations in the eastern United States are ongoing. In the Mississippi River basin, limited resources have been allocated to control its distribution, after initial detection and rapid response in Arkansas were unsuccessful. Northern snakehead distribution in the Mississippi River basin was limited to Arkansas and Mississippi until 2019 when a single northern snakehead was detected on the southern border of Missouri in the Saint Francis River drainage, the furthest northern detection. Described here are additional northern snakehead detections following public reports and subsequent monitoring in the Mingo basin of the Saint Francis River drainage, a historical braided channel and floodplain habitat of the Mississippi River with intermittently flooded bottomland hardwood forests and wetlands, and other consistent aquatic habitats. These increasing captures document the recent range expansion of northern snakehead. Most of the 11,300 ha Mingo basin consists of Mingo National Wildlife Refuge and Duck Creek Conservation Area; these areas are protected aquatic ecosystems possessing sensitive species and serve as a potential example of prioritized areas for northern snakehead control efforts. Additionally, we highlight the significance of these detections in the Mingo basin which is connected via the Castor River water-control structure to the Upper Mississippi River and may facilitate further range expansion.

Missouri↗
USGS2007

Southwest Exotic Mapping Program 2007: Occurrence summary and maps of select invasive, non-native plants in Arizona

An important aspect of management of invasive, non-native plants (invasive plants) is information on the type, location, and magnitude of infestations. Regional development of this information requires an integrated program of data collection, management, and delivery. The Southwest Exotic Plant Mapping Program (SWEMP), coordinated through the U.S. Geological Survey’s Southwest Biological Science Center, annually compiles occurrence records for infestations of invasive plants. Operating since 1998, the SWEMP team has accepted occurrence records contributed voluntarily by federal, tribal, state, and private collaborators and has compiled these contributions accumulatively with previous versions of SWEMP. The SWEMP 2007 regional database update, SWEMP07, contains 62,000 records for 221 plant species with records dating as far back as 1911 and up to December, 2006. Records include invasive plants in Arizona, eastern California, Colorado, New Mexico, and Utah. SWEMP07 is available through the Southwest Exotic Plant Information Clearinghouse ( http://sbsc.wr.usgs.gov/research/projects/swepic/swepic.asp , click SWEMP). Not all invasive plants are non-native and not all invasive plants are even invasive. The Arizona Invasive Species Advisory Council (2006) defined an invasive species as “a species that is (1) non-native to the ecosystem under consideration and, (2) whose introduction causes or is likely to cause economic or environmental harm, or harm to human health”. SWEMP uses the U.S. Department of Agriculture PLANTS database ( http://plants.usda.gov/ ) to determine if a plant is native or not to Arizona. As SWEMP does not independently assess the current or potential impact of invasive plants, we include most non-native plant records contributed. We have not included agricultural crops that are non-native, for example apples, oranges, etc. In this open-file-report, we use the SWEMP07 update to summarize the occurrence of invasive plants in Arizona and present distribution maps for a select invasive plants in Arizona. We use the word occurrence purposefully instead of the word distribution. The SWEMP07 database only provides an estimate of the actual distribution of invasive plants in Arizona. The information provided is a first approximation of the state-wide extent of invasive plant distribution.

Open-File Report↗
USGS2011

Risk assessment, eradication, and biological control: Global efforts to limit Australian acacia invasions

Aim Many Australian Acacia species have been planted around the world, some are highly valued, some are invasive, and some are both highly valued and invasive. We review global efforts to minimize the risk and limit the impact of invasions in this widely used plant group. Location Global. Methods Using information from literature sources, knowledge and experience of the authors, and the responses from a questionnaire sent to experts around the world, we reviewed: (1) a generalized life cycle of Australian acacias and how to control each life stage, (2) different management approaches and (3) what is required to help limit or prevent invasions. Results Relatively few Australian acacias have been introduced in large numbers, but all species with a long and extensive history of planting have become invasive somewhere. Australian acacias, as a group, have a high risk of becoming invasive and causing significant impacts as determined by existing assessment schemes. Moreover, in most situations, long‐lived seed banks mean it is very difficult to control established infestations. Control has focused almost exclusively on widespread invaders, and eradication has rarely been attempted. Classical biological control is being used in South Africa with increasing success. Main conclusions A greater emphasis on pro‐active rather than reactive management is required given the difficulties managing established invasions of Australian acacias. Adverse effects of proposed new introductions can be minimized by conducting detailed risk assessments in advance, planning for on‐going monitoring and management, and ensuring resources are in place for long‐term mitigation. Benign alternatives (e.g. sterile hybrids) could be developed to replace existing utilized taxa. Eradication should be set as a management goal more often to reduce the invasion debt. Introducing classical biological control agents that have a successful track‐record in South Africa to other regions and identifying new agents (notably vegetative feeders) can help mitigate existing widespread invasions. Trans‐boundary sharing of information will assist efforts to limit future invasions, in particular, management strategies need to be better evaluated, monitored, published and publicised so that global best‐practice procedures can be developed.

Diversity and Distributions↗
USGS2018

Trends in nonindigenous aquatic species richness in the United States reveal shifting spatial and temporal patterns of species introductions

Understanding the spatial and temporal dynamics underlying the introduction and spread of nonindigenous aquatic species (NAS) can provide important insights into the historical drivers of biological invasions and aid in forecasting future patterns of nonindigenous species arrival and spread. Increasingly, public databases of species observation records are being used to quantify changes in NAS distributions across space and time, and are becoming an important resource for researchers, managers, and policy-makers. Here we use publicly available data to describe trends in NAS introduction and spread across the conterminous United States over more than two centuries of observation records. Available data on first records of NAS reveal significant shifts in dominance of particular introduction patterns over time, both in terms of recipient regions and likely sources. These spatiotemporal trends at the continental scale may be subject to biases associated with regional variation in sampling effort, reporting, and data curation. We therefore also examined two additional metrics, the number of individual records and the spatial coverage of those records, which are likely to be more closely associated with sampling effort. Our results suggest that broad-scale patterns may mask considerable variation across regions, time periods, and even entities contributing to NAS sampling. In some cases, observed temporal shifts in species discovery may be influenced by dramatic fluctuations in the number and spatial extent of individual observations, reflecting the possibility that shifts in sampling effort may obscure underlying rates of NAS introduction.

Aquatic Invasions↗
USGS2022

Decline in biological soil crust N-fixing lichens linked to increasing summertime temperatures

Across many global drylands, biocrusts form a protective barrier on the soil surface and fill many critical roles in these harsh yet fragile environments. Previous short-term research suggests that climate change and invasive plant introduction can damage and alter biocrust communities, yet few long-term observations exist. Using a globally unique long-term record of continuous biocrust surveys from a rare never-grazed, protected grassland on the US Colorado Plateau, we found lichen species diversity and cover to be negatively correlated with increasing summer air temperatures, while moss species showed more sensitivity to variation in precipitation and invasive grass cover. These results suggest that dryland systems may be at a critical tipping point where ongoing warming could result in biological soil crust degradation.

Proceedings of the National Academies of Science (↗
USGS2010

Cold-induced mortality of invasive Burmese pythons in south Florida

A recent record cold spell in southern Florida (2–11 January 2010) provided an opportunity to evaluate responses of an established population of Burmese pythons ( Python molurus bivittatus ) to a prolonged period of unusually cold weather. We observed behavior, characterized thermal biology, determined fate of radio-telemetered ( n = 10) and non-telemetered ( n = 104) Burmese pythons, and analyzed habitat and environmental conditions experienced by pythons during and after a historic cold spell. Telemetered pythons had been implanted with radio-transmitters and temperature-recording data loggers prior to the cold snap. Only one of 10 telemetered pythons survived the cold snap, whereas 59 of 99 (60%) non-telemetered pythons for which we determined fate survived. Body temperatures of eight dead telemetered pythons fluctuated regularly prior to 9 January 2010, then declined substantially during the cold period (9–11 January) and exhibited no further evidence of active thermoregulation indicating they were likely dead. Unusually cold temperatures in January 2010 were clearly associated with mortality of Burmese pythons in the Everglades. Some radio-telemetered pythons appeared to exhibit maladaptive behavior during the cold spell, including attempting to bask instead of retreating to sheltered refugia. We discuss implications of our findings for persistence and spread of introduced Burmese pythons in the United States and for maximizing their rate of removal.

Florida↗
USGS2017

Lessons from the past: isotopes of an endangered rail as indicators of underlying change to tidal marsh habitats

Introduction: Tidal marsh systems along the Pacific coast of the United States have experienced substantial stress and loss of area and ecosystem function, which we examined by using the endangered California Ridgway’s Rail, Rallus obsoletus obsoletus (‘rail’) as an indicator of its tidal marsh habitat in the San Francisco Estuary. We organized a collection of historical (1885-1940) and modern (2005-2014) rail feathers and analyzed the feather isotope means for delta carbon (δ 13 C), sulfur (δ 34 S), and nitrogen (δ 15 N) by region and time period. Outcomes: Feather isotopes represented the primary foraging habitat during historical then modern time periods. Neither individual nor regional rail feather isotopes suggested freshwater or terrestrial foraging by the rail. Three regions with both historic and modern feather isotopes revealed non-uniform spatial shifts in isotope levels consistent with a marine based food web and significant δ 15 N enrichment. Discussion: Our results supported the rail’s status as a generalist forager and obligate tidal marsh species throughout the historic record. The variable isoscape trends generated from feather isotope means illustrated a modern loss of the isotopic homogeneity between regions of historical tidal marsh, which correlated with spatially-explicit habitat alterations such as increasing biological invasions and sewage effluent over time. Conclusion: These findings have reinforced the importance of tidal marsh conservation in the face of ongoing underlying changes to these important ecosystems.

California↗
USGS2021

Thermal stability of an adaptable, invasive ectotherm: Argentine giant tegus in the Greater Everglades ecosystem, USA

Invasive species globally threaten biodiversity and economies, but the ecophysiological mechanisms underlying their success are often understudied. For those alien species that also exhibit high phenotypic plasticity, such as habitat generalists, adaptations in response to environmental pressures can take place relatively quickly. The Argentine giant tegu ( Salvator merianae ; tegu) is a large omnivorous lizard from South America that is prolific, long-lived, vagile, and highly adaptable to disturbed environments. They are well suited to the climate of southeastern United States, introduced to several disjunct areas, including the Everglades, where their voracious appetite threatens native wildlife. Tegus undergo winter dormancy (hibernation) to cope with colder temperatures, and while this behavior may facilitate invasion into more temperate regions, it may also present management opportunities. We studied the thermal habits of wild S. merianae within their invaded range in southern Florida, USA. We used radiotelemetry and trail cameras to verify aboveground behaviors, and temperature dataloggers to monitor surface (sun-exposed [ T e ] and shaded [ T s ]), ambient ( T a ), subsurface ground ( T h ), and internal body ( T b ) temperatures of a population of free-ranging tegus over several seasons. We evaluated thermal and behavioral data and identified five biologically significant periods: pre-hibernal, hibernal, cold snaps, hibernal-basking, and post-hibernal. We found tegus maintained thermal stability throughout the hibernal period, frequently at temperatures above available thermal microhabitats. Variation in T b was lowest during hibernation and cold snaps and was less variable than subsurface temperatures despite not leaving their hibernaculum. Hibernal ingress and egress were best predicted by temperature differentials between exposed soil and ambient daily mean temperatures ( T e − T a ) and daylength. Though we detected no sex differences, larger animals started hibernation sooner, stayed in hibernation longer, and retained higher fat stores over the study period. One individual did not hibernate, representing only the second record of this behavior. Despite limitations of these descriptive data, this is the first study finely detailing T b of a population of wild, free-ranging S. merianae over multiple biologically significant time periods and to associate T b with thermal habitats within its invasive range. Tegus' apparent ability for thermal stability expands the adaptability breadth of this species and underscores the invasion threat.

Florida↗
USGS2009

Prevention, early detection and containment of invasive, nonnative plants in the Hawaiian Islands: current efforts and needs

Introduction: Invasive, non-native plants (or environmental weeds) have long been recognized as a major threat to the native biodiversity of oceanic islands (Cronk & Fuller, 1995; Denslow, 2003). Globally, several hundred non-native plant species have been reported to have major impacts on natural areas on oceanic islands (Kueffer et al ., 2009). In Hawaii, at least some 50 non-native plant species reach dominance in natural areas (Kueffer et al ., 2009) and many of them are known to impact ecosystem processes or biodiversity. One example is the invasive Australian tree fern ( Cyathea cooperi ), which has been shown to be very efficient at utilizing soil nitrogen and can grow six times as rapidly in height, maintain four times more fronds, and produce significantly more fertile fronds per month than the native Hawaiian endemic tree ferns, Cibotium spp. (Durand & Goldstein, 2001a, b). Additionally, while native tree ferns provide an ideal substrate for epiphytic growth of many understory ferns and flowering plants, the Australian tree fern has the effect of impoverishing the understory and failing to support an abundance of native epiphytes (Medeiros & Loope, 1993). Other notorious examples of invasive plant species problematic for biodiversity and ecosystem processes in Hawaii include miconia ( Miconia calvescens ), strawberry guava ( Psidium cattleianum ), albizia ( Falcataria moluccana ), firetree ( Morella faya ), clidemia ( Clidemia hirta ), kahili ginger ( Hedychium gardnerianum ), and fountain grass ( Pennisetum setaceum ), to name just a few. Fireweed ( Senecio madagascariensis ) is a recent example of a seriously problematic invasive species for Hawaii’s agriculture and is damaging certain high-elevations native ecosystems as well. The threat of invasive plants has long been recognized in Hawaii and is well documented (e.g. Cox, 1999; Loope & Kraus, 2009 in press; Loope et al ., 2004; Mooney & Drake, 1986; Stone & Scott, 1985; Stone et al. , 1992). In many respects, Hawaii may be near the forefront among national and international efforts to address the burgeoning threat of invasive plants, perhaps especially in the field of outreach and education (Holt, 1996; Van Driesche & Van Driesche, 2000). However, given the scale of the problem many challenges still need to be addressed and gaps in the existing management system need to be identified. In particular, it appears that new non-native plant species are still introduced to the Hawaiian Islands at a high rate with little or no regard for their potential invasiveness. In fact, a Pacific-wide and a global survey of non-native plants on oceanic islands have both shown that on Hawaii among all archipelagos by far the highest number of problematic invasive species known from other areas in the world is already present (Denslow et al . 2009, Kueffer et al . 2009). Hawaii lacks an effective mechanism for tracking what species are present or incoming. For instance, early detection nursery surveys conducted on Maui in 2008 found over 300 species of cultivated vascular plants that have not previously been recorded in Hawaii (Starr et al. , in prep.). In spite of an innovative Hawaii Biological Survey (e.g. Eldredge & Evenhuis, 2003), there is no mechanism for recording presence of a species until it becomes naturalized. Some of these new introductions may quickly become serious pests. Fireweed, first recorded in Hawaii on the Big Island in the early 1980s, is now considered one of the Kueffer & Loope 2009 5/48 worst weeds of pastures and is also invading natural areas from near sea level to above 10,000 feet. Although the cultivated and as yet non-invasive Cortaderia selloana has been present in Hawaii for 50 years or more, the morphologically similar Cortaderia jubata was simultaneously found to be present on Maui and invading on a large scale in 1989. It played an important role in inspiring the establishment of the Maui Invasive Species Committee (MISC) in 1997, and MISC now spends roughly $200,000 per year removing and containing C. jubata to keep it from becoming widespread in high elevation conservation lands of East and West Maui. The existence of many similar examples shows that to date regulatory action to prevent new invasive plant species from establishing and spreading in Hawaii has not yet been as successful as it needs to be. In particular, because some problematic invasive species known from other areas in the world (Kueffer et al ., 2009; Weber, 2003) have not yet been recorded from Hawaii, preventive measures against the introduction and spread of such likely invasive species is therefore an urgent need for Hawaii. Indeed, regulation of importation and early detection and eradication of introduced species before they become abundant and widespread are widely considered the most cost-efficient and often only effective measures against the threat of new invasive species (Kueffer & Hirsch Hadorn, 2008; Wittenberg & Cock, 2001). Timing seems favorable for Hawaii to achieve effective protection against the threat of new invasive species through prevention, early detection, and eradication/containment. Through the establishment and evolution of Invasive Species Committees (ISCs) on each major Hawaiian island, the institutional capacity has been built up for prevention, early detection, containment, and outreach at an island scale. Weed risk assessment (Daehler et al ., 2004) and early detection methodologies (Starr et al. , in review-a, b) have been developed and tested specifically for Hawaii. Containment strategies have been successful (e.g., Special Ecological Areas in Hawaii Volcanoes National Park), and so have eradications of particular species on an island scale (e.g. mullein ( Verbascum thapsus ) and other species on Maui, fireweed ( Senecio madagascariensis ) on Kauai). These successful management strategies may be further strengthened through recently developed novel approaches in research (e.g. remote sensing, species distribution modelling, and molecular genetics tools). Another major recent achievement is the gained support of the plant industry for preventive measures against invasive species (see p. 13ff). Last but not least, regulatory action is also moving forward. Passage of House Bill 2517 by the 2008 Hawaii House and Senate and prompt signing of the bill into law by the Governor provides hope that action to ban the sale of a meaningful suite of restricted weeds can quickly proceed through the rulemaking phase into the implementation phase. This report documents these achievements and experiences and provides a range of perspectives on how to further develop prevention, early detection and containment of invasive species in Hawaii. The report is based on a symposium and workshop held at the 2008 Hawaii Conservation Conference in Honolulu on 31 July 2008.

Hawaii↗
USGS2016

Integrating subsistence practice and species distribution modeling: assessing invasive elodea’s potential impact on Native Alaskan subsistence of Chinook salmon and whitefish

Alaska has one of the most rapidly changing climates on earth and is experiencing an accelerated rate of human disturbance, including resource extraction and transportation infrastructure development. Combined, these factors increase the state’s vulnerability to biological invasion, which can have acute negative impacts on ecological integrity and subsistence practices. Of growing concern is the spread of Alaska’s first documented freshwater aquatic invasive plant Elodea spp. (elodea). In this study, we modeled the suitable habitat of elodea using global and state-specific species occurrence records and environmental variables, in concert with an ensemble of model algorithms. Furthermore, we sought to incorporate local subsistence concerns by using Native Alaskan knowledge and available statewide subsistence harvest data to assess the potential threat posed by elodea to Chinook salmon ( Oncorhynchus tshawytscha ) and whitefish ( Coregonus nelsonii ) subsistence. State models were applied to future climate (2040–2059) using five general circulation models best suited for Alaska. Model evaluations indicated that our results had moderate to strong predictability, with area under the receiver-operating characteristic curve values above 0.80 and classification accuracies ranging from 66 to 89 %. State models provided a more robust assessment of elodea habitat suitability. These ensembles revealed different levels of management concern statewide, based on the interaction of fish subsistence patterns, known spawning and rearing sites, and elodea habitat suitability, thus highlighting regions with additional need for targeted monitoring. Our results suggest that this approach can hold great utility for invasion risk assessments and better facilitate the inclusion of local stakeholder concerns in conservation planning and management.

Alaska↗
USGS2024

Understanding gaps in early detection of and rapid response to invasive species in the United States: A literature review and bibliometric analysis

While concepts regarding invasive species establishment patterns and eradication possibilities have long been a topic of invasion biology, the specific terminology referring to early detection of and rapid response to (EDRR) invasive species emerged in scientific literature during the early 2000s. Since then, the EDRR approach has expanded to include a suite of detection, planning, and management tools. By conducting a systematic literature review, we attempt to characterize the field of EDRR in the United States and its territories as reflected by publication records. Specifically, we assessed publication data such as the number of publications per year, the most common journals where papers were published, and the relationship between author’s keywords for studies focusing on aquatic and terrestrial habitats. For publications that used invasive species occurrence or abundance data (whether collected for the purposes of the respective publication or acquired from another data source), we manually vetted additional information such as focal taxa, data collection years and locations, sources of other data used, and whether data or code were deposited in open access formats. We also conducted network analyses for the author institutions that coauthored papers together most frequently and for the references most cited by EDRR publications. Overall, we found that silos existed in terms of which author institutions worked together, which existing literature was cited, and which topics were frequently explored. We also found evidence of substantial gaps in data access and use. For example, although a wide variety of data sources for invasive species occurrences are available, these sources were seldom cited by published literature, and newly collected data was not often deposited into invasive species databases or other open-source data repositories. Considering the continued advocation for a centralized national EDRR information system, our study suggests that facilitating access to data, decision support tools, and other informational resources represents a key opportunity for improving EDRR capabilities.

Ecological Informatics↗
USGS2026

Long lives, short futures: Freshwater turtle and tortoise imports to the United States highlight global trade and conservation challenges

Global trade of freshwater turtles and tortoises presents substantial conservation, biosecurity, and regulatory challenges, particularly for long-lived species that are already highly imperiled. While the United States has historically played a key role in supplying the international chelonian trade, investigations into its role as an importer remain limited. We used import data from the U.S. Fish and Wildlife Service Law Enforcement Management Information System (LEMIS) between 2000 and 2022 to evaluate the trade of freshwater turtles and tortoises. Over 2.5 million individuals were imported into the United States during this period, comprising 172 species that are likely imported for the pet trade, food, and traditional medicine markets. Reported annual imports for freshwater turtles increased until approximately 2013 and decreased thereafter, whereas reported annual imports for tortoises have remained relatively constant. Two species, Chinese softshell turtles ( Pelodiscus sinensis ) and Horsfield's tortoises ( Testudo horsfieldii ) represent 62.9% of all imports. Imported species were largely classified as Vulnerable, Endangered, or Critically Endangered by the IUCN Red List, yet the conservation status of a concerning number of species ( n = 45; 26.2%) has not been evaluated. Many imports appear to be sourced from wild populations (28.3% of freshwater turtles, 71.3% of tortoises); however, captive-sourced imports increased significantly over time across both groups. Import volumes raise concerns regarding the sustainability of freshwater turtle and tortoise trade, the potential for invasive species establishment, and disease spread. Our results highlight the need for updated IUCN assessments, verification of trade records, and strengthening of biosecurity screening at U.S. ports of entry.

Biological Conservation↗
USGS2021

Using enclosed Y-mazes to assess chemosensory behavior in reptiles

Reptiles utilize a variety of environmental cues to inform and drive animal behavior such as chemical scent trails produced by food or conspecifics. Decrypting the scent-trailing behavior of vertebrates, particularly invasive species, enables the discovery of cues that induce exploratory behavior and can aid in the development of valuable basic and applied biological tools. However, pinpointing behaviors dominantly driven by chemical cues versus other competing environmental cues can be challenging. Y-mazes are common tools used in animal behavior research that allow quantification of vertebrate chemosensory behavior across a range of taxa. By reducing external stimuli, Y-mazes remove confounding factors and present focal animals with a binary choice. In our Y-maze studies, a scenting animal is restricted to one arm of the maze to leave a scent trail and is removed once scent-laying parameters have been met. Then, depending on the trial type, either the focal animal is allowed into the maze, or a competing scent trail is created. The result is a record of the focal animal's choice and behavior while discriminating between the chemical cues presented. Here, two Y-maze apparatuses tailored to different invasive reptile species: Argentine black and white tegu lizards (Salvator merianae) and Burmese pythons (Python bivittatus) are described, outlining the operation and cleaning of these Y-mazes. Further, the variety of data produced, experimental drawbacks and solutions, and suggested data analysis frameworks have been summarized.

Journal of Visualized Experiments↗
USGS2021

Understanding mast seeding for conservation and land management

Masting, the intermittent and synchronous production of large seed crops, can have profound consequences for plant populations and the food webs that are built on their seeds. For centuries, people have recorded mast crops because of their importance in managing wildlife populations. In the past 30 years, we have begun to recognize the importance of masting in conserving and managing many other aspects of the environment: promoting the regeneration of forests following fire or other disturbance, conserving rare plants, conscientiously developing the use of edible seeds as non-timber forest products, coping with the consequences of extinctions on seed dispersal, reducing the impacts of plant invasions with biological control, suppressing zoonotic diseases and preventing depredation of endemic fauna. We summarize current instances and future possibilities of a broad set of applications of masting. By exploring in detail several case studies, we develop new perspectives on how solutions to pressing conservation and land management problems may benefit by better understanding the dynamics of seed production. A lesson common to these examples is that masting can be used to time management, and often, to do this effectively, we need models that explicitly forecast masting and the dynamics of seed-eating animals into the near-term future.

Philosophical Transactions of the Royal Society B:↗
USGS2018

Evaluating GPS biologging technology for studying spatial ecology of large constricting snakes

Background : GPS telemetry has revolutionized the study of animal spatial ecology in the last two decades. Until recently, it has mainly been deployed on large mammals and birds, but the technology is rapidly becoming miniaturized, and applications in diverse taxa are becoming possible. Large constricting snakes are top predators in their ecosystems, and accordingly they are often a management priority, whether their populations are threatened or invasive. Fine-scale GPS tracking datasets could greatly improve our ability to understand and manage these snakes, but the ability of this new technology to deliver high-quality data in this system is unproven. In order to evaluate GPS technology in large constrictors, we GPS-tagged 13 Burmese pythons ( Python bivittatu s) in Everglades National Park and deployed an additional 7 GPS tags on stationary platforms to evaluate habitat-driven biases in GPS locations. Both python and test platform GPS tags were programmed to attempt a GPS fix every 90 min. Results : While overall fix rates for the tagged pythons were low (18.1%), we were still able to obtain an average of 14.5 locations/animal/week, a large improvement over once-weekly VHF tracking. We found overall accuracy and precision to be very good (mean accuracy = 7.3 m, mean precision = 12.9 m), but a very few imprecise locations were still recorded (0.2% of locations with precision > 1.0 km). We found that dense vegetation did decrease fix rate, but we concluded that the low observed fix rate was also due to python microhabitat selection underground or underwater. Half of our recovered pythons were either missing their tag or the tag had malfunctioned, resulting in no data being recovered. Conclusions : GPS biologging technology is a promising tool for obtaining frequent, accurate, and precise locations of large constricting snakes. We recommend future studies couple GPS telemetry with frequent VHF locations in order to reduce bias and limit the impact of catastrophic failures on data collection, and we recommend improvements to GPS tag design to lessen the frequency of these failures.

Florida↗
USGS2005

Sex structure and potential female fecundity in a Epinephelus guttatus spawning aggregation: Applying ultrasonic imaging

Ultrasonic imaging was used to determine the spawning population structure and develop a fecundity estimation model for a red hind Epinephelus guttatus spawning aggregation within the Red Hind Bank Marine Conservation District, St Thomas, U.S.V.I. The spawning population showed considerable within‐month and between‐month variation in population size‐ and sex‐structure. In the spawning season studied, males appeared to arrive at the aggregation site first in December although females represented a large proportion of the catch early in the aggregation periods in January and February. Spawning occurred in January and February, and size frequency distributions suggested that an influx of small females occurred during the second spawning month. An overall sex ratio of 2·9 : 1 (female : male) was recorded for the whole reproductive season. The sex ratio, however, differed between months and days within months. More females per male were recorded in January than in February when the sex ratio was male biased. Fecundity estimates for this species predicted very high potential fecundities (2·4 × 10 5 −2·4 × 10 6 oocytes). The ultrasound model also illustrated a rapid increase in potential female fecundity with total length. Ultrasonic imaging may prove a valuable tool in population assessment for many species and locations in which invasive fishing methods are clearly undesirable.

Journal of Fish Biology↗
USGS2018

Exotic predators may threaten another island ecosystem: A comprehensive assessment of python and boa reports from the Florida Keys

Summarizing historical records of potentially invasive species increases understanding of propagule pressure, spatiotemporal trends, and establishment risk of these species. We compiled records of non-native pythons and boas from the Florida Keys, cross-referenced them to eliminate duplicates, and categorized each record’s credibility. We report on 159 observations of six python and boa species in the Florida Keys over the past 17 years. Burmese pythons (Python bivittatus), boa constrictors (Boa constrictor), and ball pythons (Python regius) are the most frequently reported species, but credible records of three additional species were also reported. Among the most notable records, we report on three hatchling and multiple reproductive Burmese pythons captured on North Key Largo since 2016, indicating that the species is now established on that island. The expanding mainland Burmese python population and ongoing python and boa introductions via pet and cargo pathways are likely to keep propagule pressure high in coming years. Both effective public outreach to solicit reporting of sightings and effective early detection and rapid response networks may help to prevent further establishment and associated ecological impacts of python and boa species in the Florida Keys.

Florida↗
USGS2017

Management implications of broadband sound in modulating wild silver carp (Hypophthalmichthys molitrix) behavior

Invasive silver carp (Hypophthalmichthys molitrix) dominate large regions of the Mississippi River drainage, outcompete native species, and are notorious for their prolific and unusual jumping behavior. High densities of juvenile and adult (~25 kg) carp are known to jump up to 3 m above the water surface in response to moving watercraft. Broadband sound recorded from an outboard motor (100 hp at 32 km/hr) can modulate their behavior in captivity; however, the response of wild silver carp to broadband sound has yet to be determined. In this experiment, broadband sound (0.06–10 kHz) elicited jumping behavior from silver carp in the Spoon River near Havana, IL independent of boat movement, indicating acoustic stimulus alone is sufficient to induce jumping. Furthermore, the number of jumping fish decreased with subsequent sound exposures. Understanding silver carp jumping is not only important from a behavioral standpoint, it is also critical to determine effective techniques for controlling this harmful species, such as herding fish into a net for removal.

Illinois↗