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USGS2021

Agkistrodon conanti (Florida Cottonmouth) and Python bivittatus (Burmese Python). Diet and Predation

Python bivittatus is established in the Greater Everglades Ecosystem in southern Florida, USA. Documented predators on pythons in Florida include Alligator mississippiensis (American Alligator; Snow et al. 2006. Herpetol. Rev. 37:81–81), Drymarchon couperi (Gulf Coast Indigo Snake; Andreadis et al. 2018. Herpetol. Rev. 49:341–342), Lynx rufus (Bobcat; McCollister et al. 2021. Southeast. Nat. 20:N55–N59), and possibly Ursus americanus floridanus (Florida Black Bear; McCollister et al. 2021. op cit.). We documented mortality events of hatchling and juvenile P. bivittatus while conducting radiotelemetry studies in the Greater Everglades Ecosystem.

Florida↗

USGS1975

Structure and Paleozoic stratigraphy of a complex of thrust plates in the Fish Creek Reservoir area, south-central Idaho

Permian, Pennsylvanian, Mississippian, Devonian, and Silurian marine rocks of diverse facies are brought together in a complex of six thrust sheets in the Fish Creek Reservoir area on the north edge of the Snake River Plain, Idaho. The lowest structural element, the parautochthon, is made of more than 450 m (1,500 ft) of folded and faulted Devonian miogeosynclinal carbonate rocks present in a 6.5-km 2 (2.5-mi 2 ) window. Along the east margin of the window, a sliver of continental margin transitional carbonate rocks of Early Devonian and Late Silurian age assigned to the Roberts Mountains Formation is thrust over the miogeosynclinal rocks. The window of middle Paleozoic rocks is overridden along the Fish Creek thrust fault by the flysch facies of the Copper Basin Formation, a turbidite-submarine-fan sequence more than 1,000 m (3,300 ft) thick, of Mississippian age. About 4.8 km (3 mi) southwest of the window, about 100 m (300 ft) of deepwater siliceous oceanic facies clastic rocks are exposed, which are assigned with question to the Milligen(?) Formation of Devonian age. These clastic rocks are interpreted to be thrust over the Copper Basin Formation. The highest structural elements are sequences more than 610 m (2,000 ft) thick of interbedded sandy and conglomeratic limestones, quartzites, and conglomerates and interbedded siltstones and argillites of the Wood River Formation of Middle Pennsylvanian to Early Permian age. The Wood River Formation is in thrust contact with the Milligen(?) Formation in the southwest part of the mapped area and with Copper Basin Formation along the west side of Fish Creek Reservoir. All the thrust sheets have moved eastward. The minimum distance moved is estimated from sedimentation models and facies reconstructions to range from perhaps several kilometres for the allochthon of the Roberts Mountains Formation to 48 km (30 mi) for the Milligen(?) Formation allochthon. The principal period of thrusting was post-Early Permian (post-Wood River Formation) and preEocene (pre-Challis Volcanics) and is of probable Sevier age. Middle Paleozoic rocks of the Milligen and Roberts Mountains Formations, however, also may have been involved in an earlier period of thrusting of latest Devonian to earliest Mississippian age related to the Antler orogeny. The thrust sheets were deformed into a northwest-trending dome in late Mesozoic time and were broken by basin-range faults during the Tertiary.

Idaho↗

USGS2023

New maps of conductive heat flow in the Great Basin, USA: Separating conductive and convective influences

Geothermal well data from Southern Methodist University and the U.S. Geological Survey (USGS) were used to create maps of estimated background conductive heat flow across the Great Basin region of the western United States. These heat flow maps were generated as part of the USGS hydrothermal and Enhanced Geothermal Systems resource assessment process, and the creation process seeks to remove the influence of hydrothermal convection from the predictions of the background conductive heat flow. The heat flow maps were constructed using a custom-developed iterative process using weighted regression, in which convectively influenced outliers were de-emphasized by assigning lower weights to measurements with heat flow values further from the estimated local trend (e.g., local convective influence). The local linear weighted regression algorithm is two-dimensional locally estimated scatterplot smoothing where smoothness was controlled by varying the number of nearby wells used for each local interpolation. Three maps resulting from conductive heat flow models are detailed in this paper, highlighting the influence of measurement confidence. The three maps use either: measurements from all wells with equal weight (no confidence weights), or one of two different published categorization methods to de-emphasize low-quality measurements; one categorization method graded thermal gradient quality, the other categorization method graded thermal conductivity quality. Each map is an estimate of background conductive heat flow as a function of reported data quality, and a point coverage is also provided for all wells in the compiled dataset. The point coverage includes an important new attribute for geothermal wells: the residual, which can be interpreted as the departure of a well from the estimated background heat flow conditions, and the value of the residual may be useful in identifying the influence of fluids (hydrothermal or groundwater) on conductive heat flow. Of the three maps presented, the map that de-emphasized the impact of wells with low-quality thermal gradient measurements appears to perform best because it did not incorporate many of the wells in the Snake River Plain that do not penetrate the aquifer and are therefore very unlikely to reflect true conductive conditions.

Great Basin↗

USGS2022

Natives bite back! Are Burmese pythons beginning to encounter the resilience of the Everglades Ecosystem?

Burmese pythons ( Python bivittatus ) is a large, invasive reptile known in Florida for its devastating impacts on native species in the Greater Everglades Ecosystem. Several organizations and individuals are taking action to research and/or remove the snakes, including the U.S. Geological Survey (USGS). Since 2018, scientists from USGS’s Fort Collins Science Center have been working closely with the National Park Service (NPS) in Big Cypress National Preserve to use radiotelemetry and track Burmese pythons for various ecological research project and management (enabled by invaluable partnerships with the University of Florida and Zoo Miami). Over those years, we have encountered some incidental, but intriguing findings.

Florida↗

USGS2023

Burmese python size and reproduction: Fact vs fiction

We’ve probably all heard rumors about monster 25-foot snakes or baby pythons emerging from under neighbors houses year-round, but what is fact vs fiction? To help us sort truth from myth, invasive pythons that were removed from the Everglades and surrendered to the National Park Service (NPS) were scientifically investigated via a partnership with the U.S. Geological Survey Fort Collins Science Center’s (USGS FORT) Invasive Species Science Branch. Other contributing partners were South Florida Water Management District and Florida Fish and Wildlife Conservation Commission’s Python Contractor and Agent programs. Over the past 25 years more than 4,000 wild Burmese pythons have been found and removed from southern Florida’s Greater Everglades Ecosystem.

Everglades Cooperative Invasive Species Management↗

USGS2024

Nerodia clarkii (Saltmarsh Watersnake). Predation

Predators of Nerodia clarkii are suspected to include larger species of crabs, fish, wading birds, snakes, alligators, and crocodiles. To our knowledge, there have only been two published observations of predation on N. clarkii, including a predation attempt from a Callinectes sapidus (Blue Crab) in Mississippi, USA and a successful predation by a Grus americana (Whooping Crane) in Texas, USA. Herein we report on predation of N. clarkii and a suspected Nerodia clarkii x fasciata pictiventris (Saltmarsh Watersnake and Florida Banded Watersnake) hybrid by Crocodylus acutus (American Crocodile) in South Florida, USA.

Herpetological Review↗

USGS2023

Nonsalmonid gas bubble trauma investigations

From 2020 to 2023, a new spill program was implemented to aid the downstream passage of juvenile salmonids at mainstem dams on the Snake and Columbia rivers. Under this program, the total dissolved gas (TDG) cap was increased to 125% and monitoring of nonsalmonids for gas bubble trauma (GBT) became a requirement. The primary objective of this work and report was to measure the incidence and severity of GBT in nonsalmonids resulting from increased juvenile salmonid passage spill and associated levels of TDG during the spring spill period in 2023. Nonsalmonids were collected downstream from Bonneville, McNary, Ice Harbor, and Lower Granite dams and examined for the incidence and severity of GBT in 2023. Fish were collected at each location weekly (3 April to 20 June) during the spring spill period by backpack electrofishing and beach seining. Washington and Oregon State water quality agencies established minimum and target sample sizes for monitoring, but the minimum sample size of 50 fish and target sample size of 100 fish were not met in all weeks at individual projects due to high water flows and resulting low fish collections. Collected fish were examined for GBT according to the criteria and protocol established for the regional smolt monitoring program (SMP). TDG levels were often high relative to the 10-year average. GBT incidence rates and severity (according to SMP criteria) were low to moderate in most weeks. We found no apparent relationship between GBT incidence and TDG due to exposure history and interspecies susceptibility to elevated TDG that could not be quantified. GBT incidence rates exceeded the 15% threshold on two occasions below Ice Harbor Dam, triggering a reduction in spill under the State water quality standards. In the weeks immediately following the spill reductions, GBT incidence was zero or relatively low at this location. Sculpin (genus Cottus ) was the main species collected at all locations. As in past years, we did find GBT in non-SMP protocol areas, particularly in sculpin. The variability in GBT incidence rates is likely due to variability in environmental conditions, fish exposure history to TDG, and species sensitivity to TDG. Many of the species encountered in shallow shoreline habitats rear for extended times and probably do not seek the water depths that would help them reduce the effects of exposure to elevated TDG through depth compensation. Limited systematic sampling of TDG in the tailraces of each project showed that TDG can vary spatially within the tailrace and with percentage of water spilled. We investigated GBT progression and mortality in sculpin and threespine stickleback ( Gasterosteus aculeatus ) in laboratory experiments (Chapter Two of this report). Fish were tested at 120%, 125%, and 130% TDG. We found that sculpin are more sensitive to TDG than stickleback and that GBT and associated mortality progress faster in sculpin than in stickleback. GBT prevalence and severity increased through time at all TDG levels tested, but relationships between severity and exposure time were weak or nonexistent. GBT and mortality progressed more rapidly as TDG increased in both species. The SMP criteria used to rank GBT did not fully capture the incidence and severity of GBT in sculpin and stickleback compared to using criteria based on all areas of the fish. The lateral line, body, dorsal fin, and pectoral fins were common locations of GBT in sculpin at 120 and 125% TDG, but signs were more prevalent in all areas at 130% TDG. In stickleback, GBT was most common on the head and body at all TDG levels tested. Positive buoyancy of fish with severe GBT was observed in both species and may have consequences for similarly impaired fish in the wild. The proximate cause of GBT-related death in sculpin and stickleback was bubbles in the gills and heart, but unlike in other species, bubbles appeared rapidly just before the point of death. Our results help fill the information void GBT progression and mortality for sculpin and stickleback.

Oregon, Washington↗

USGS2019

Yellowstone convenes science information sharing panel on aquatic invasive species

Yellowstone National Park (YNP) supports one of the most significant aquatic ecosystems in the U.S. Headwater streams and rivers emerge from the park and join to become three of America’s most important waterways and ultimately flow into the Pacific and Atlantic oceans: the Yellowstone River, the Missouri River and the Snake River. At the heart of YNP lies Yellowstone Lake – the largest alpine body of water in North America. The park encompasses about 2.25 million acres, five percent of which is covered by water, including more than 220 lakes and 2,650 miles of streams.

Idaho, Montana, Wyoming↗

USGS2018

A geophysical characterization of the structural framework of the Camas Prairie Geothermal System, southcentral Idaho

Play Fairway Analysis methods, utilizing existing geologic, thermal, geochemical, and geophysical data were employed in an initial assessment of geothermal resources in the Snake River Plain. These efforts identified the Camas Prairie in southcentral Idaho as a region with elevated resource potential. Subsequent efforts included structural and geophysical data collection to identify the most favorable structural settings for exploiting resources in the valley. The present work involved high-resolution gravity, magnetic, magnetotellurics (MT), field mapping, and seismic surveys to further characterize the system and target sites for exploration drilling around Barron’s Hot Springs (BHS) in the southwest part of the valley. Geophysical mapping and modeling reveal that the BHS coincides with a complex intersection of two major fault systems: a prominent NW-trending system that includes the Pothole fault, and EW-trending basin-bounding faults that control NS-extension. This complex zone includes a dense network of EW-oriented faults and a right stepover in the Pothole fault which, given the dominant dextral-normal to normal slip inferred for this fault, would promote extension in the immediate vicinity of the BHS. Surface faulting in this region indicate Pleistocene or younger slip, and seismic imaging documents offsets of shallow strata that suggest ongoing activity on these structures. MT modeling results show that this zone also coincides with a prominent conductive anomaly, characteristic of the presence of hydrothermal alteration or hydrothermal fluids. These results point to the importance of these structures in maintaining current and long-lived shallow hydrothermal activity around the BHS. The detailed structural mapping and conceptual framework developed from this study provide critical constraints for siting a drill hole aimed at documenting reservoir characteristics and informing potential future development of these geothermal resources.

Idaho↗

USGS2024

Nonsalmonid gas bubble trauma investigations

From 2020 to 2024, a new spill program was implemented to aid the downstream passage of juvenile salmonids at mainstem dams on the Snake and Columbia rivers. Under this program, the total dissolved gas (TDG) cap was increased to 125% and monitoring of nonsalmonids for gas bubble trauma (GBT) became a requirement. The primary objective of this work and report was to measure the incidence and severity of GBT in nonsalmonids resulting from increased juvenile salmonid passage spill and associated levels of TDG during the spring spill period in 2024. Nonsalmonids were collected downstream from Bonneville, McNary, Ice Harbor, and Lower Granite dams and examined for the incidence and severity of GBT. Fish were collected at each location weekly during the spring spill period (3 April to 20 June) by backpack electrofishing and beach seining. Washington and Oregon state water quality agencies established minimum and target sample sizes for monitoring, but the minimum sample size of 50 fish and target sample size of 100 fish were not met in all weeks at individual projects due to low fish collections. Collected fish were examined for GBT according to the criteria and protocol established for the regional smolt monitoring program (SMP). In 2024, a new method of calculating GBT incidence rate was requested by the Washington Department of Ecology but the Oregon Department of Environmental Quality retained the calculation method that was used in past years. GBT incidence rates and severity (evaluated using both calculation methods) were low to moderate in most weeks. GBT rates never exceeded thresholds that would have triggered a reduction in spill. We found no strong relationship between GBT incidence and TDG due to exposure history and interspecies susceptibility to elevated TDG that could not be quantified. Sculpin (genus Cottus) was the main species collected at all locations but northern pikeminnow composed a significant portion of the catch at Ice Harbor and Lower Granite dams early in the season. After four years of field sampling, we conclude 1) the occupancy and catchability of native nonsalmonids is difficult and highly variable in dam tailraces, which in turn, often makes meeting collection targets challenging, 2) GBT incidence rate calculation methods can be modified to account for differing species abundances in the daily catch, 3) native nonsalmonids differ in their sensitivity to elevated TDG, and 4) predicting the incidence of GBT in native nonsalmonids from field measurements of TDG will remain difficult given the inherent variability in GBT incidence both within and between species.

Report↗

USGS1995

Common ravens in the southwestern United States, 1968-92

The common raven ( Corvus corax ) is a large black passerine bird found throughout the northern hemisphere including western and northern North America. Ravens are scavengers that frequently feed on road-killed animals, large dead mammals, and human refuse. They kill and eat prey including rodents, lambs (Larsen and Dietrich 1970), birds, frogs, scorpions, beetles, lizards, and snakes. They also feed on nuts, grains, fruits, and other plant matter (Knight and Call 1980; Heinrich 1989). Their recent population increase is of concern because ravens eat agricultural crops and animals whose populations may be depleted. Ravens are closely associated with human activities, frequently visiting solid-waste landfills and garbage containers at parks and food establishments, being pests of agricultural crops, and nesting on many human-made structures. In two recent surveys in the deserts of California (FaunaWest Wildlife Consultants 1989; Knight and Kawashima 1993), ravens were more numerous in areas with more human influences, and were often indicators of the degree to which humans affect an area. Annual Breeding Bird Surveys (BBS) conducted nationwide by the U.S. Fish and Wildlife Service (USFWS) indicated that raven populations in several parts of the country significantly increased during 1965-79 (Robbins et al. 1986). This increase concerns resource managers because ravens feed on agricultural crops and animal species of interest to humans. For instance, in the deserts of the southwestern United States, ravens prey on young desert tortoises ( Gopherus agassizii ; Berry 1985; Fig. 1), which in the Mojave and Colorado deserts are listed as a threatened species by the USFWS (Federal Register 1990). Because of high levels of raven predation on tortoises, the Bureau of Land Management has taken action to reduce this predation (BLM 1990, 1994). We report here on a 24-year trend in raven abundance along roadsides in the deserts of the southwestern United States and surrounding regions, where increasing raven populations interest resource management agencies (BLM 1990; USFWS 1994). Our analysis of BBS 1968-92 data focuses on arid lands and neighboring habitats in California, Nevada, Utah, and Arizona. We used data from 137 39.2-km (24.5-mi) routes within the following BBS strata: Great Basin Desert; mountain highlands of Arizona; Sonoran-Colorado Desert; Mojave Desert; basins and ranges, including portions of the northern Mojave and Great Basin deserts; Central Valley; and southern California grasslands, California foothills (southern California routes only), and Los Angeles ranges combined into one (coastal southern California).

Book chapter↗

USGS2002

Strategic plan for the Coordinated Intermountain Restoration Project

In 1982, the Bureau of Land Management’s (BLM) Idaho State Office began the Intermountain Greenstripping and Rehabilitation Research Project (IGRRP), or the “Greenstripping Program,” to investigate plant materials and technologies that can reduce wildfire incidence and improve rehabilitation practices. Rehabilitation is normally applied as a reactive process to wildfires, yet land managers in the Great Basin wish to become proactive by replacing fire-prone invasive annual grasses with native plants. The Coordinated Intermountain Restoration Project (CIRP) evolved from the Greenstripping Program to conduct research studies and provide technical assistance on restoration of native ecosystems on rangelands that are infested with invasive annual grasses or other invasive or noxious weeds. To accomplish this objective, the CIRP will promote the understanding of ecosystem disturbance dynamics as well as evaluate plant materials, site preparation techniques, weed control methods, seeding equipment, management methods, and monitoring techniques for restoration projects. The CIRP will not address the restoration of forested or woodland (juniper [Juniperus]) ecosystems. It will include a component on fuel management to reduce the impacts of wildfires on semiarid rangeland ecosystems where exotic annual grasses provide the fuel. The people who will benefit directly from this research include land managers and users of public and private lands in the northern Great Basin, the Columbia Plateau, and the Snake River Plain. The CIRP will provide an integration framework for a multidisciplinary approach to research with numerous opportunities for input and collaboration. The U.S. Geological Survey will initially dedicate approximately \$1 million over 5 years (about \$200,000 per year) to jump-start this effort. U.S. Geological Survey funds will establish a science advisory board to oversee the project. This board will contain members of Federal research and management agencies within the region. U.S. Geological Survey funds will support (1) continued development of VegSpec, a computer program that is a restoration expert system, (2) research to examine changes in ecosystem processes when native plant-dominated communities shift to communities dominated by exotic annual grasses, and (3) research to address mechanisms for establishing native plants in locations dominated by exotic annual grasses. Through these initial funds, USGS hopes to leverage additional research with other agencies (e.g., BLM’s Great Basin Restoration Initiative or the Native Plant Materials Development Project, which is an interagency program to supply and manage native plant materials for restoration and rehabilitation on Federal lands) or funding organizations (e.g., the U.S. Department of Agriculture’s [USDA] National Research Initiative Competitive Grants Program, or the USDA’s and U.S. Department of the Interior’s [USDOI] Joint Fire Science Program), and to obtain additional research partners (e.g., university or Federal scientists) willing to expand this effort to address all aspects of this strategic plan.