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At least 649 records · Page 36Linked to original sources
USGS2015

The effect of weather on morphometric traits of juvenile cliff swallows

Episodes of food deprivation may change how nestling birds allocate energy to the growth of skeletal and feather morphological traits during development. Cliff swallows ( Petrochelidon pyrrhonota ) are colonial, insectivorous birds that regularly experience brief periods of severe weather-induced food deprivation during the nesting season which may affect offspring development. We investigated how annual variation in timing of rearing and weather were associated with length of wing and tail, skeletal traits, and body mass in juvenile cliff swallows reared in southwestern Nebraska during 2001–2006. As predicted under conditions of food deprivation, nestling skeletal and feather measurements were generally smaller in cooler years. However, variability explained by weather was small, suggesting that morphometric traits of juvenile cliff swallows were not highly sensitive to weather conditions experienced during this study. Measurements of juvenile morphological traits were positively correlated with measurements taken as adults, meaning that any variation among juveniles in response to rearing conditions showed evidence of persisting into a bird’s first breeding season. Our results show that body size in this species is phenotypically plastic and influenced, in part, by weather variables.

Nebraska↗
USGS2009

Twenty-three years of vegetation change in a fly-ash leachate impacted meadow

1. Blag Slough, located in Indiana Dunes National Lakeshore, has received leachates from nearby fly-ash ponds for 13 years (1967-1980). We have monitored vegetation and sediment of Blag Slough since 1982, two years after the sealing of the fly-ash ponds and one year after the substrate was first exposed. The pH of the soil has increased one order of magnitude from 3.0 to 4.0 over the 23 years (1982-2005). If the pH further increases the solubility of many heavy metals will decrease, except for arsenic. We provide evidence that boron and zinc were bioaccumulating in the leaves of woody plants in 1984. The ratio of leaf concentration and soil concentration of aluminum suggests this element was not bioaccumulating in woody plants in 1984. 2. Soil concentrations of iron, aluminum, arsenic, and strontium were higher nearest the fly-ash ponds in 2005. The southwest corner of Blag Slough and middle position of transect X had the highest elevated levels of these metals and correlated with the occurrence of mixed spikerush association (dominated by Eleocharis olivacea). 3. Only a few exotic species occurred in the Blag Slough. Common reed (Phragmites australis) was among such species that occurred in three large clones. Other exotic species included dandelion (Taraxacum officinale), mullein (Verbascum thapsis), Jerusalem oak goosefoot (Chenopodium botrys), and sheep sorrel (Rumex acetosella). Ruderal species have occurred including thistle (Cirsium spp.), fire weed (Erechtites hieracifolium), and horseweed (Conyza canadensis). While occasional cattail (Typha) have been sampled and mapped in Blag Slough they have never persisted for very long. 4. Species richness leveled off between 1991 and 2005, except for Transect X that had a peak in 1986-7. After an extreme rainfall event in August 18, 1990, Transect V had an average water depth of 0.70 cm, W had 7.1 cm, and X had 26.90 cm. Richness in Transect X declined to a low level in 1990 and 1991 after the extreme flooding event because this transect had the deepest surface water. 5. Typical late successional vegetation associations developed since 1991 include blue joint grass (Calamagrostis canadensis) and buttonbush (Cephalanthus occidentalis), but large areas consist of disturbance-dependent mosaics of rush (Juncus effusus) and other species. The large expanses of woolly sedge (Scirpus cyperinus) that dominated in the 1980’s was replaced by rush. 6. Late-successional associations (Glyceria canadensis and Calamagrostis canadensis) were closer to the wetland edge compared to the other associations after the dewatering. This pattern occurred because wet meadow vegetation persisted at the wetland edge during the period of industrial flooding, but since then these associations expanded greatly into the north half of Blag Slough. 7. Richness, diversity, and floristic quality index (FQI) increased with time at the plot, association, association trajectories, and wetland levels; whereas mean conservatism scores (mean C), the basis of FQI calculation, decreased in time. The high C values, assigned to coastal plain disjunct species and shrubs by judgment of botanists based on their empirical xii experience including regional or state level plant conservation designations are largely responsible for the contradicted trend between FQI and C. Such contradiction highlights a problem with the subjective assignment of C values, and thus the inadequacy of application of FQI in these wetland systems. 8. Occurrence of interveinal clearing in winged sumac (Rhus copallina), late boneset (Eupatorium serotinum), and black dewberry (Rubus occidentalis) suggest a potential phytotoxicity by heavy metals. However, cause-effect relationship between the metals and the plants are yet to be investigated. Nevertheless, boron and zinc accumulation ratios in leaves of woody plants (Betula populifolia, Populus tremuloides, Rhus copallina, and Rubus sp.) in 1984 suggest that boron and zinc were bioaccumulating in those species. Known toxicity effects of aluminum suggest that plants with vein clearing may be experiencing toxic effects of aluminum despite leaf concentrations 58 to 193 ppm. 9. In a greenhouse experiment, rye (Secale cereale) and radish (Raphanus sativus) germinated poorly in the sediments from Blag Slough having high concentrations of heavy metals (ZN, Mn, B, and NH4+) compared to potting soil. However, rye and radish plants grown in Blag Slough soil had shorter shoots and roots, lower root and shoot mass, and lower root to shoot mass ratios compared to plants grown in potting soil. These results suggest some effect of the soil constituents on rye and radish growth. 10. Positive signs in the recovery of Blag Slough include the increase in soil pH, the increasing dominance of late successional grasses, and the establishment of wetland zonation relative to seasonal water depth. Some areas of Blag Slough near the fly-ash ponds that continue to have high concentrations of heavy metals continue to be devoid of vegetation or are dominated by early successional species such as green spikerush. Localized heavy metal concentrations, evidence for zinc and boron bioaccumulation in 1984, vein clearing that persists today, effects of soil on rye and racish growth, and slow succession in the southern portion of Blag Slough suggest further toxicity study is necessary to better assess the impacts on this wetland ecosystem and identify restoration actions.

Indiana↗
USGS2009

Status and trends of the Lake Huron deepwater demersal fish ommunity, 2008

The U.S.Geological Survey Great Lakes Science Center has conducted trawl surveys to assess annual changes in the deepwater demersal fish community of Lake Huron since 1973. Since 1992, surveys have been carried out using a 21 m wing trawl towed on-contour at depths ranging from 9 to 110 m on fixed transects. Sample sites include five ports in U.S. waters with less frequent sampling near Goderich, Ontario. The 2008 fall bottom trawl survey was carried out between October 24 and November 20, 2008 and sampled only the three northern U.S. ports at DeTour, Hammond Bay, and Alpena due to mechanical problems with the research vessel and prolonged periods of bad weather. Therefore, all data presented for 2008 are based on samples collected from these ports. Compared to previous years, alewife populations in Lake Huron remain at low levels after collapsing in 2004. Age-0 alewife density and biomass appears to have increased slightly but overall levels remain near the nadir observed in 2004. Density and biomass of adult and juvenile rainbow smelt showed a decrease from 2007 despite record-high abundance of juveniles observed in 2005, suggesting recruitment was low. Numbers of adult and juvenile bloater were low despite recent high year-classes. Abundances for most other prey species were similar to the low levels observed in 2005 - 2007. We captured one wild juvenile lake trout in 2008 representing the fifth consecutive year that wild lake trout were captured in the survey. Based on pairwise graphical comparisons and nonparametric correlation analyses, dynamics of prey abundance at the three northern ports followed lakewide trends since 1992. Density of benthic macroinvertebrates was at an all-time low in 2008 since sampling began in 2001. The decline in abundance was due to decreases in all taxonomic groups and a large reduction in recruitment of quagga mussels. Density of Diporeia at northern ports in 2008 was the lowest observed. Diporeia were found only at 73-m sites of three ports sampled in northern Lake Huron. While no lakewide estimate of prey biomass was calculated due to the limited spatial scope of the 2008 survey, existing data suggest prey biomass remains depressed. Prey available to salmonids during 2009 will likely be small alewives, small rainbow smelt and small bloaters. Predators in Lake Huron will continue to face potential prey shortages.

Lake Huron↗
USGS1982

Predation on seabirds by red foxes at Shaiak Island, Alaska

Two Red Foxes (Vulpes fulva ) that invaded Shaiak Island before the 1976 nesting season had a marked impact on the nesting success of five of seven species of seabirds breeding on the island that year. Common Eiders ( Somateria mollissima ), Glaucous-winged Gulls ( Larus glaucescens ), and Common Murres ( Uria aalge ), that nest in areas accessible to foxes, did not raise any young to fledging. Double-crested Cormorants ( Phalacrocorax auritus ) were only slightly more successful; 13 (4.3%) of 300 pairs raised one or more young to fledging. Evidence suggested that 21 (35.6%) of 62 pairs of Tufted Puffins (Lunda cirrhata ) lost eggs or chicks to foxes, and foxes killed at least 13 (8.3%) of 156 adult puffins on ten sample plots. Conversely, Black-Legged Kittiwakes ( Rissa tridactyl a) and Pelagic Cormorants ( Phalacrocorax pelagicus ), which nested primarily on cliffs inaccessible to foxes, lost very few nests. There was no apparent change in general nest site selections by seabirds the following year, when foxes were no longer present. Any avoidance by birds of areas vulnerable to fox predation would probably be discernible only after several years of continuous predation.

Alaska↗
USGS1987

Volcanic ash clouds; a continuing threat to international aviation

There was no warning. The British Airqays Boeing 747 was making its usual flight from Kuala Lumpur to Perth, Asutralia, that nihgt, late in June 1982. Altitude:12,000 metres (37,000 feet). Time about 23:00 UTC. Suddenly, an acrid odour began to pervade the aircraft, an eerie bluish glow lit up the edges of the wings, and in the cockpit the familiar hum of static started to break up the high-frequency communications. Then it happened.

Earthquakes & Volcanoes (USGS)↗
USGS2003

Demography of Dall's sheep in northwestern Alaska

Dall’s sheep in northwestern Alaska declined in the early 1990s following the severe 1989-90 and 1990-91 winters. In the Baird Mountains of Noatak National Preserve, estimates of adult sheep declined by 50% from 800 in 1989 to under 400 in 1991. Population counts remained low throughout 1991 to 1996, reaching a minimum of 244 adult sheep in 1996. Few lambs were observed during annual midsummer aerial surveys in 1991 to 1994. We suspect that these declines resulted from a combination of poorer nutritional condition and increased vulnerability of sheep to predation resulting from severe winter conditions. As a result of these declines, both subsistence and sport hunting seasons were closed by emergency order in 1991, resulting in substantial management controversy. The affected publics, although willing to accept the closures, questioned the validity of the sheep survey data and strongly emphasized their interest in restoring harvests as soon as populations increased sufficiently. In 1995 the Northwest Arctic Regional Advisory Council, the local advisory committee for the Federal Subsistence Board, passed a motion supporting efforts to initiate research on sheep populations in the region to better understand the factors limiting sheep populations and to evaluate sheep survey methodologies. Currently estimates of Dall’s sheep population size and composition in the western Brooks Range are based on intensive fixed-wing aerial surveys conducted annually since 1986 in areas including the Baird Mountains. The annual variation in recent Baird Mountains aerial counts cannot be explained with reasonable assumptions about reproduction and survival, suggesting that there is some variability in the proportion of the population observed each year or that a substantial number of sheep move during the survey. Prior to our research, no attempt had been made to estimate visibility bias or precision for these surveys. Our understanding of Dall’s sheep population biology comes largely from studies in central or southern Alaska and the southern Yukon. However, sheep in northwestern Alaska are at the northwestern extreme of their range and live in a less hospitable environment characterized by short growing seasons and long, severe winters. We expect patterns of productivity and survival for sheep in Noatak National Preserve to differ from the more southerly populations. To adequately manage sheep harvests in northwestern Alaska, we need a better understanding of sheep demography. Along with unbiased population estimates, understanding the dynamics of sheep populations in the region will allow population models to be developed that can provide focus for a useful dialog on management goals and strategies and facilitate a cooperative strategy for managing sheep harvests in northwestern Alaska.

Alaska↗
USGS2008

Bats prove to be rich reservoirs for emerging viruses

Emerging pathogens, many of them viruses, continue to surprise us, providing many newly recognized diseases to study and to try to control. Many of these emergent viruses are zoonotic, transmitted from reservoirs in wild or domestic animals to humans, either by insect vectors or by exposure to the droppings or tissues of such animals. One rich- but, until recently, underappreciated-source of emergent viruses is bats ( Chiroptera , meaning "hand wing"). Accounting for 1,116, or nearly one fourth, of the 4,600 recognized species of mammals, bats are grouped into two suborders Megachiroptera, which contains a single family, Pteropodidae, consisting of 42 genera and 186 species, and Microchiroptera, which contains 17 families, 160 genera, and 930 species. Although bats are among the most abundant, diverse, and geographically dispersed orders of terrestrial mammals, research on these flying mammals historically focused more on their habits and outward characteristics than on their role in carrying microorganisms and transmitting pathogens to other species. Even in those cases where bats were known to carry particular pathogens, the microbiologists who studied those pathogens typically knew little about the bat hosts. Hence, investigators now are seeking to explain how variations of anatomy, physiology, ecology, and behavior influence the roles of bats as hosts for viral pathogens.

Microbe↗
USGS1983

The fledging of common and thick-billed murres on Middleton Island, Alaska

Three species of alcids, Common and Thick-billed murres ( Uria aalge and U. lomvia ) and the Razorbill ( Alca torda ), have post-hatching developmental patterns intermediate to precocial and semi-precocial modes (Sealy 1973). The young leave their cliff nest sites at about one quarter of adult weight and complete their growth at sea. At departure, an event here loosely referred to as "fledging," neither primary nor secondary flight feathers are grown, but well-developed wing coverts enable limited, descending flight.

Alaska↗
USGS1983

Atlantic Flyway review: Region V: Laurel, Prince Georges County, MD (390-0765)

Nets were operated at this suburban backyard station before and after work during the week, and all day on as many weekends as possible, from 23 August to 30 November. A trip to Spain interrupted banding in mid-September and accounted for the drop in both species and individuals banded. This also explains the 66% drop in Gray Catbirds, which was by far my most common species last year. As in past years, no netting was done within 15 m of the bird feeders, and no traps were baited until the nets were removed in December. White-throated Sparrows (9) and Carolina Chickadees (7) accounted for half of my returns. The oldest returns were a 6-year-old White-throated Sparrow and a 7-year-old Carolina Chickadee. The only species banded in unusually large numbers were American Robin and Black-throated Blue Warbler. A Red-shouldered Hawk and a Golden-winged Warbler raised the species total for this station to 112. Three birds remained here long enough to increase their weight by more than 30%: an HY female Black-and-white Warbler arrived on 29 August with a weight of 11.2 g and was last captured on 5 September with a weight of 17.1 g. It took an HY Ovenbird 24 days to increase from 20.8 g to the 28.2 g that it weighed when last caught on 13 October. A Swainson's Thrush, on the other hand, went from 36.5 g to 48.1 g between 10 and 14 October. Other heavy-weights were Hairy Woodpecker, 74.4 g; Blue Jay, 103.2 g; Gray Catbird, 46.4 g; Wood Thrush, 64.1 g; and White-eyed Vireo, 15.0 g.

Maryland↗
USGS2000

Response of geese to aircraft disturbances

Low-flying aircraft can affect behavior, physiology, and distribution of wildlife (Manci et al., 1988), and over time, may impact a population by reducing survival and reproductive performance. Thus, it is important to identify the particular aspects of overflights that affect animals so that management strategies can be developed to minimize adverse effects. Waterfowl are particularly sensitive to low-flying aircraft (Manci et al., 1988) and respond at all stages of their annual cycle, including breeding (Gollop et al., 1974a; Laing, 1991), molting (Derksen et al., 1979; Mosbech and Glahder, 1991), migration (Jones and Jones, 1966; Belanger and Bedard, 1989), and wintering (Owens, 1977; Kramer et al., 1979; Henry, 1980). Waterfowl response can be quite variable both within and among species (Fleming et al., 1996). For example, response can vary with age, sex, and body condition of individual, habitat type and quality, and previous exposure to aircraft (Dahlgren and Korshgen, 1992). However, the most important factors influencing a response are aircraft type (Davis and Wiseley, 1974; Jensen, 1990), noise (Mosbech and Glahder, 1991; Temple, 1993), and proximity to the birds, as measured in altitude and lateral distance (Derksen et al., 1979; Belanger and Bedard, 1989; Ward et al., 1994). Wildlife managers can reduce impacts on a population by controlling or modifying these factors. In an experimental study conducted at Izembek Lagoon in southwestern Alaska in 1985-1988 (Ward and Stehn, 1989), we conducted planned aircraft overflights with control of aircraft type, noise, altitude, and lateral distance to flocks (hereafter called lateral distance) to measure behavioral response of fall-staging Pacific brant ( Branta bernicla nigricans ) and Canada geese ( B. canadensis taverneri ) to fixed- and rotary-wing aircraft. These data were then used to develop predictive models of the relationship between aircraft type, noise, altitude, and lateral distance and the response of geese (Ward et al., 1989). We also developed a simulation model incorporating energy intake and daily energy costs to assess the long-term consequences of repeated overflights on the ability of brant to obtain sufficient energy reserves necessary for fall migration and over winter survival (Ward and Stehn, 1989).

Alaska↗
USGS1994

Comparison of age determination techniques for female northern pintails and American wigeon in spring

Accurate age-class determination of waterfowl is necessary for studies addressing age-specific effects (e.g., Serie et al., 1992) and age structure of populations (e.g., Raveling and Heitmeyer 1989). Duck ages can be determined in fall by morphological and color characteristics of tertial and tail feathers (Carney 1992); however, these feathers are replaced during fall and winter, thus their characteristics cannot be used in spring (Dane 1968). Other methods used to determine waterfowl age include the presence or absence of the bursa of Fabricius (hereafter bursa; Gower 1939, Hochbaum 1942, Hanson 1949) and characteristics of primary and secondary wing feathers and their coverts (e.g., Wishart 1981, Duncan 1985).

Wildlife Society Bulletin↗
USGS2017

Datasheet: Pseudogymnoascus destructans (white-nose syndrome fungus)

Pseudogymnoascus destructans is a psychrophilic (cold-loving) fungus that causes white-nose syndrome (WNS), an emerging disease of North American bats that has caused unprecedented population declines. The fungus is believed to have been introduced to North America from Europe or Asia (where it is present but does not cause significant mortality), but the full extent of its native range is unknown. The route of introduction is also unknown. In North America, hibernating bats become infected with P. destructans when body temperature decreases during winter torpor into the range permissive for growth of this fungus. Infected bats may develop visible fungal growth on the nose or wings, awaken more frequently from torpor, and experience a cascade of physiologic changes that result in weight loss, dehydration, electrolyte imbalances, and death. P. destructans persists in the environments of underground bat hibernation sites (hibernacula) and is believed to spread primarily by natural movements of infected bats. The first evidence of WNS in North America is from a photograph of a hibernating bat taken during winter of 2005-2006 in a hibernaculum near Albany, New York. P. destructans subsequently spread rapidly from the northeastern United States throughout much of the eastern portions of the United States and Canada, and most recently (as of May 2017) was detected in Washington State. It has killed millions of bats, threatening some species with regional extirpation and putting at risk the valuable environmental services that bats provide by eating harmful insects.

Book chapter↗
USGS2012

Morphometric-based sexual determination of Bananaquits (Coereba flaveola)

The Bananaquit (Coereba flaveola) is a common passerine throughout the tropics and has been a convenient species for ecological studies. This species has sexually monomorphic plumage and cannot be reliably sexed unless in breeding condition. This is problematic for demographic and comparative studies, which are contingent upon accurately aging and sexing individuals. Although male Bananaquits are larger than females, there is overlap in both wing chord and mass. We used morphometric data collected over eight years to develop a predictive model based on logistic regression to assign adult Bananaquits to sex. Our model classified 96% of validation individuals to the correct sex. We suggest that this approach may enhance ecological studies of the species by facilitating correct sex determination independent of breeding status. We believe our modeling approach is applicable elsewhere but, because there may be geographical variation across the species distribution, models will need to be customized to local populations.

Guana Island↗
USGS2014

Factors affecting fat content in mottled ducks on the Upper Texas Gulf Coast

Body condition, or an individual's ability to address metabolic needs, is an important measure of organism health. For waterfowl, body condition, usually some measure of fat, provides a useful proxy for assessing energy budgets during different life history periods and potentially is a measure of response to ecosystem changes. The mottled duck (Anas fulvigula) is relatively poorly studied in respect to these dynamics and presents a unique case because its non-migratory life-history strategy releases it from metabolic costs experienced by many related migratory waterfowl species. Additionally, as a species in decline and of conservation concern in many parts of its range, traditional methods of fat content estimation that involve destructive sampling are less viable. The goal of this study was to produce an equation for estimating fat content in mottled ducks using birds (n = 24) donated at hunter-check stations or collected by law enforcement efforts on the Texas Chenier Plain National Wildlife Refuge Complex from 2005 - 2007. Morphometric measurements were taken, and ether extraction and fat removal was used to estimate percent body fat content and abdominal fat mass, respectively. A hierarchical simple linear regression modeling approach was used to determine external morphometrics that best predicted abdominal fat content. A ratio model based on body mass and a length metric (keel and wing chord length possessed equal model support) provided the best relationship with abdominal fat in sampled individuals. We then applied the regression equation to historical check station data to examine fluctuations in fat content over time; fat content or condition varied relatively little with the exception of years characterized by major disturbances. The mottled duck condition model created here can be used to better monitor population status and health without destructively sampling individuals.

Journal of the Southeastern Association of Fish an↗
USGS2012

Nest defense- Grassland bird responses to snakes

Predation is the primary source of nest mortality for most passerines; thus, behaviors to reduce the impacts of predation are frequently quantified to study learning, adaptation, and coevolution among predator and prey species. Video surveillance of nests has made it possible to examine real-time parental nest defense. During 1999-2009, we used video camera systems to monitor 518 nests of grassland birds. We reviewed video of 48 visits by snakes to 34 nests; 37 of these visits resulted in predation of active nests. When adult birds encountered snakes at the nest (n = 33 visits), 76% of the encounters resulted in a form of nest defense (nonaggressive or aggressive); in 47% of the encounters, birds physically struck snakes. When defending nests, most birds pecked at the snakes; Eastern Meadowlarks (Sturnella magna) and Bobolinks (Dolichonyx oryzivorus) pecked most frequently in anyone encounter. Also, two Eastern Meadowlarks ran around snakes, frequently with wings spread, and three Bobolinks struck at snakes from the air. Nest defense rarely appeared to alter snake behavior; the contents of seven nests defended aggressively and two nests defended nonaggressively were partially depredated, whereas the contents of six nests defended each way were consumed completely. One fledgling was produced at each of three nests that had been aggressively defended. During aggressive defense, one snake appeared to be driven away and one was wounded. Our findings should be a useful starting point for further research. For example, future researchers may be able to determine whether the behavioral variation we observed in nest defense reflects species differences, anatomic or phylogenetic constraints, or individual differences related to a bird's prior experience. There appears to be much potential for studying nest defense behavior using video recording of both real and simulated encounters.

Studies in Avian Biology↗
USGS2019

Monitoring and conservation of Japanese Murrelets and related seabirds in Japan

Of the 24 species in the Auk (or Alcidae) family of seabirds living in the northern hemisphere, 22 reside within the North Pacific Ocean. These “penguins of the north” use their small wings to “fly” underwater, some to more than 200 meters, where they catch and eat a variety of small fish and invertebrates. In terms of sheer numbers (>65 million) and food consumption, the Auks dominate seabird communities on our continental shelves and they serve as indicators of the health of our ocean. If Auk populations are not all thriving, then we should be concerned about the status of the oceans, plankton and fish that normally sustain them. A few Auk “tribes” genera) are abundant and widespread (such as Uria murres and Aethia auklets), and some are rare and isolated such as Synthliboramphus murrelets, including the Japanese “Crested” Murrelet). Only 8 species of Auk breed in Japan, including species that have either widespread or isolated populations in the North Pacific. During the past century, most of these Auks have declined dramatically in Japan from many causes, including the introduction of predatory rats and cats to breeding islands, bycatch in fishing nets, alteration of food supplies by fishing and climate change, oil spills, and destruction of seabird nesting habitats. Widespread species such as the Common Murre and Tufted Puffin were once common in Japan but now breed in low numbers at only a few locations. Probably common in the past, small numbers of the widespread Ancient Murrelet were recently re-discovered breeding at Teuri Island, which is also home to the world’s largest colony of Rhinoceros Auklet, another widespread species. Though common throughout the North Pacific, Pigeon Guillemots, breed only in the southern Kuril Islands. Their population status is unknown, but they were never considered common in Japan. In contrast, Spectacled Guillemots are an example of an uncommon and isolated population of Auk. They nest along coasts of the Sea of Okhotsk and Sea of Japan, and populations have declined in recent decades. The Long-billed Murrelet has a similar distribution to Spectacled Guillemot, and once bred in Hokkaido, but populations appear to have been extirpated. The Japanese Murrelet has a very small world population, and breeds at only a few locations in southern Japan and the Republic of Korea. The international community of research and conservation biologists is greatly concerned about the ability of this species—probably the rarest of all Auks in the world— to maintain its population size. Owing to its small size and high metabolic demand, this species is especially vulnerable to any stress that increases its food requirements such as changing fish stocks, disturbance on feeding or wintering grounds, or changing ocean climate. Immediate management actions are needed to preserve Japanese Murrelets and other Auks in Japan, by such means as eradicating rats and cats on breeding islands, altering fishing gear to minimize bycatch, and reducing human disturbance to nesting habitats. More research and monitoring of Auk populations in Japan is needed to track population trends, and further identify factors responsible for declines. Interaction between governments and biologists at regional and international levels will be mutually beneficial as we all strive to conserve precious resources and biodiversity in the northwest Pacific, and particularly the Japanese islands.

Conference Paper↗
USGS2019

Integrating magnetotellurics, soil gas geochemistry and structural analysis to identify hidden, high enthalpy, extensional geothermal systems

We applied magnetotellurics (MT), diagnostic structural affiliations, soil gas flux, and fluid geochemistry to assist in identifying hidden, high-enthalpy geothermal systems in extensional regimes of the U.S. Great Basin. We are specifically looking for high-angle, low-resistivity zones and dilatant geologic structures that can carry fluids from magmatic or high-grade metamorphic conditions in the deep crust upward to exploitable depths, and to verify the nature of the deep sources through soil gas and fluid compositions. The project was motivated by prior MT transect coverage of western and central Nevada centered upon the Dixie Valley producing geothermal system where such favorable indicators were first recognized. The high-angle MT structures are taken to be fluidized fault zones connecting deep magmatic/metamorphic activity with the geothermal system, but the concept required verification by testing at other systems. The project was set up with a two-phased organization. Phase I was carried out at the McGinness Hills system, central Nevada, where Ormat Inc flagship power facility is located and a considerable amount of pre-existing data were available. Resistivity models along MT transects also showed a strong low-resistivity upwelling originating from interpreted deep crustal magmatic underplating. Controlling structures on production as indicated by Ormat data and our new mapping were favorable to dilatancy, comprising an accommodation zone between major normal faults of opposing dip. A 3D MT survey and inversion confirmed the existence of the steep low-resistivity zone dipping ESE toward the deep crust and placed N-S bounds upon the feature. In cooperation with Ormat personnel, we sampled well fluids from production intervals for He isotope composition. Elevated 3He was verified through mass spectrometry analysis confirming a magmatic connection with the producing system. High CO2 soil gas flux including possibly metamorphic 13C and 14C component was measured over the area of dilatant structures. Hence, the triad of indicators posed above was confirmed in Phase I. Subsequently, Phase II of the project proceeded in the greenfield Kumiva-Blackrock Desert district of northwestern Nevada to see if a new system could be identified. Transect MT data also showed a low-resistivity upwelling originating from interpreted deep crustal magmatic underplating. An MT survey of 131 sites was imaged through 3D inversion using an in-house, DOE-supported finite element algorithm. Low resistivity upwellings that warranted follow up study occur under the flanks of the Seven Troughs Range, under Kumiva Playa immediately west of the Blue Wing Mountains, and under northern Granite Springs Valley. Structural assessment of the project area by Co-I J. Faulds at UNR provided numerous favorable Quaternary fault settings, which were correlated to the MT upwelling structures. Soil CO2 gas flux anomalies generally were not large but did show correlation with resistivity upwelling structure and favorable geological structures. Isotope analyses showed presence of possible inorganic/metamorphic 13C but 14C concentrations did not exceed background values. We view the initial concept of a confluence of low-resistivity upwelling, favorably dilatant 3D geological structure, and elevated soil gas flux including 13C component to be supported by the further evidence of this project although the indicators in the Phase II study were more diffuse. Mass balance calculations based upon 3He R/Ra values indicates that the proportion of magmatic fluids in a producing system is fairly low, 10-15% by volume. We suggest that the diagnostic MT geophysical structures denote zones of concentrated extensional deformation that increases permeability, potentially enabling a circulating upper crustal geothermal system, while at the same time connecting telltale deep component signatures to the upper crust. The northern Granite Springs Valley structure is receiving followup stu

Nevada↗
USGS2020

Bug flows: Don’t count your midges until they hatch

Usually when people hear about a “bug problem” it’s due to an undesirable overabundance of insects (think plague of locusts). In the Colorado River in Grand Canyon, however, we are faced with the opposite predicament: the river is essentially devoid of bugs. Aquatic insects are a fundamental component of a healthy river ecosystem. Most aquatic insects spend their juvenile life stages (egg, larva, pupa) in the river and their winged adult life stage flying along the riparian corridor. Throughout these metamorphoses one thing is for certain: aquatic insects are prey for fish, birds, bats, lizards, and even other invertebrates. In Grand Canyon, food web studies conducted by the US Geological Survey (USGS) have demonstrated that populations of both native and sport fish are food limited (Cross et al. 2013, Kennedy et al. 2013). In other words, fish in Grand Canyon are consistently facing a calorie deficit. Indeed, the US Fish and Wildlife Service has cited the inadequate and unreliable food supply as the single greatest problem facing endangered Humpback Chub populations in the Grand Canyon (USFWS 2019).

Boatman's Quarterly Review↗