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At least 145 records · Page 8Linked to original sources
USGS1953

Radioactive source materials in Los Estados Unidos de Venezuela

This report summarizes the data available on radioactive source materials in Los Estados Unidos de Venezuela accumulated by geologists of the Direccions Tecnica de Geolgia and antecedent agencies prior to June 1951, and the writers from June to November 1951. The investigation comprised preliminary study, field examination, office studies, and the preparation of this report, in which the areas and localities examined are described in detail, the uranium potentialities of Venezuela are summarized, and recommendations are made. Preliminary study was made to select areas and rock types that were known or reported to be radioactive or that geologic experience suggests would be favorable host for uranium deposits, In the office, a study of gamma-ray well logs was started as one means of amassing general radiometric data and of rapidly scanning many of ye rocks in northern Venezuela; gamma-ray logs from about 140 representative wells were examined and their peaks of gamma intensity evaluated; in addition samples were analyzed radiometrically, and petrographically. Radiometic reconnaissance was made in the field during about 3 months of 1951, or about 12 areas, including over 100 localities in the State of Miranda, Carabobo, Yaracuy, Falcon, Lara, Trujillo, Zulia, Merida, Tachira, Bolivar, and Territory Delta Amacuro. During the course of the investigation, both in the filed and office, information was given about geology of uranium deposits, and in techniques used in prospecting and analysis. All studies and this report are designed to supplement and to strengthen the Direccion Tecnica de Geologias's program of investigation of radioactive source in Venezuela now in progress. The uranium potentialities of Los Estados de Venezuela are excellent for large, low-grade deposits of uraniferous phospahtic shales containing from 0.002 to 0.027 percent uranium; fair, for small or moderate-sized, low-grade placer deposits of thorium, rare-earth, and uranium minerals; poor, for high-grade hydrothermal pitchblende deposits; and highly possible for small, medium- to high-grade despots of carnotite-or copper-uranium bearing sandstone. Recommendations for the Venezuelan uranium program include 1) the systematic collection of a mass general radiometric data by examining sample collections, expanding the gamma-ray program, encouraging the use of Geiger counter by field geologists, and by enlisting the aid of the general public; 2) , the examination of specific areas or localities, chosen on the basis of geologic favorability from the results of the amassing of data, or obtained by hints and rumors; 3), the organization of a unit within the Direccion Tecnica de Geologica to direct, collection, and collate metric data. It is emphasized that to be most fruitful the program requires the application of sounds and imaginative geologic theory.

Trace Elements Investigations↗
USGS2002

Characterization of selenium in the lower Gunnison River basin, Colorado, 1988-2000

Selenium concentrations in certain water bodies in the lower Gunnison River Basin, including the lower Gunnison River and lower Uncompahgre River, have exceeded the Colorado water-quality standard of 5 micrograms per liter for selenium. A task force was formed in 1998 that consists of various government agencies, private irrigation companies, and local residents to address the selenium concerns in the lower Gunnison River Basin. The task force, working with the National Irrigation Water Quality Program, needed more detailed information on selenium loading in the basin to develop viable alternatives for remediating selenium in the lower Gunnison River Basin. In 1999-2000, the U.S. Geological Survey collected selenium data for tributaries of the Gunnison River downstream from the North Fork of the Gunnison and in the North Fork Basin. The largest selenium load in a tributary stream was in the Uncompahgre River, which accounted for about 38 percent of the selenium load in the Gunnison River at Whitewater. The North Fork of the Gunnison River accounted for about 7 percent of the selenium load in the Gunnison River. Two tributaries east of Delta, Sunflower Drain and Bonafide Ditch, consist primarily of irrigation return flows and were other major selenium sources to the Gunnison River. Some tributaries in the lower North Fork Basin had selenium concentrations exceeding 5 micrograms per liter. Except for several streams draining the Uncompahgre Plateau, many tributaries to the Gunnison River downstream from the North Fork had selenium concentrations exceeding 5 micrograms per liter. Except during occasional rain and snowmelt events, selenium loading from nonirrigated desert areas was minimal. Detailed characterization studies were done in 1999-2000 on Cedar Creek and Loutzenhizer Arroyo, which contribute the largest tributary selenium loads to the Uncompahgre River. Selenium concentrations in Cedar Creek downstream from Miguel Road ranged from 12 to 28 micrograms per liter in November 1999. Montrose Arroyo was the largest selenium source to Cedar Creek. On an annual basis, about 20 percent of the selenium load in Cedar Creek originates in the basin upstream from Miguel Road. Selenium concentrations in Loutzenhizer Arroyo ranged from 157 to 347 micrograms per liter in February 2000. A significant increase in selenium concentrations occurred in the stream reach between the Selig Canal and Falcon Road (LZU7). Although selenium concentrations in the west tributary of Loutzenhizer Arroyo were lower than in the main stem, the west tributary contributed about 41 percent of the selenium load. Downstream from the confluence with the west tributary to the mouth, selenium concentrations in the arroyo gradually decreased, and the increase in selenium load in the lower reach was small.

Water-Resources Investigations Report↗
USGS1974

Floods of September-October 1967 in south Texas and northeastern Mexico

Floods produced by Hurricane Beulah during September and October 1967 were outstanding because of the magnitude of the stage and discharge and because of the number of river basins affected. Previously known maximum stages were exceeded, at the downstream station, in five river basins in Texas by amounts ranging from 2.7 feet at Guadalupe River near Tivoli to 9.2 feet at Aransas River near Skidmore. The greatest relative maximum discharge recorded during the storm occurred at Medio Creek near Beeville, where the peak discharge was 4.1 times the previous maximum since 1919 and 6.0 times the magnitude of a regional 50-year flood. The inflow to Lake Corpus Christi was more than 4.5 times the volume of the lake at spillway elevation. Because of the large volume of fresh-water inflow to bays and estuaries along the Texas coast, the salinity of the water was greatly reduced. Data collected in Nueces Corpus Christi and Guadalupe San Antonio Bays show that dilution proceeded rapidly along the line of flow. Fresh-water inflow to Corpus Christi Bay exceeded 60,000 cubic feet per second from September 23 through September 28. The total inflow was about 1.5 times the volume of water normally in the bay, but because of its shape and depth, the bay was not entirely flushed of saline water. Fresh-water inflow to San Antonio Bay exceeded 40,000 cubic feet per second from September 21 through September 26. The total inflow was more than three times the volume of water normally in the bay, and most of the saline water was flushed from the bay. Measurements of water levels in wells indicate that Hurricane Beulah caused significant rises in water levels in shallow wells by percolation of rainfall and ponded waters and by the cascading of floodwaters directly into numerous inundated wells. Flooding along the Rio Grande and its floodways below Falcon Dam was the greatest since the American floodway system was completed in 1926. At Mission Branch Floodway, south of McAllen, Tex., the peak discharge was 2.15 times the previous maximum in 1932. The peak stage exceeded the previous maximum by 4.14 feet. Flooding along the Mexican floodways destroyed all stream-gaging equipment. A 4,000-square-mile area of south Texas having no defined drainage system contains thousands of shallow wind-formed depressions. These normally dry depressions were inundated by the storm runoff, which produced a vast amount of ponded water. The ponds blocked highways for several days and hampered ranching and oil field operations for months after the storm. Rainfall measurements of 25 inches during the period September 19-25, 1967, were common in Texas, and as much as 35 inches was measured in Mexico. Total damage in 39 counties of Texas was estimated by the Galveston District of the Corps of Engineers to be $168,844,000.

Water Supply Paper↗
USGS2009

Unusual raptor nests around the world

From surveys in many countries, we report raptors using unusual nesting materials (e.g., paper money, rags, metal, antlers, and large bones) and unusual nesting situations. For example, we documented nests of Steppe Eagles Aquila nipalensis and Upland Buzzards Buteo hemilasius on the ground beside well-traveled roads, Saker Falcon Falco cherrug eyries in attics and a cistern, and Osprey Pandion haliaetus nests on the masts of boats and on a suspended automobile. Other records include a Golden Eagle A. chrysaetos nest 7.0 m in height, believed to be the tallest nest ever described, and, for the same species, we report nesting in rudimentary nests. Some nest sites are within a few meters of known predators or competitors. These unusual observations may be important in revealing the plasticity of a species' behavioral repertoire. ?? 2009 The Raptor Research Foundation, Inc.

Journal of Raptor Research↗
USGS1995

Survival and population size estimation in raptor studies: A comparison of two methods

ABSTRACT.--The Jolly-Seber model is a capture-recapture model that can provide less-biased survival and population size estimates than those produced from simple counting procedures. Parameter estimation by simple counts and Jolly-Seber methods are based on certain assumptions that directly determine the validity of estimates. Evuluation of assumptions for parameter estimation is a focus of this paper and used as a basis for determining which methods are more likely to produce better estimates. An example of population size and survival estimation for a peregrine falcon(Falco peregrinus) population in western Greenland is used to compare the two methods.Based on results from the Greenland peregrine population, and an assessment of the underlying assumptions of simple counts and the Jolly-Seber model,we suggest that Jolly-Seber estimation of survival and population size is less biased than simple counts in studies with marked birds. We recommend the use of a Jolly-Seber analysis of data when capture-recapture techniques are employed in raptor population studies.

Journal of Raptor Research↗
USGS2001

Influence of military activities on raptor abundance and behavior

We investigated the influence of military training on the abundance and behavior of raptors at a military training area in the Snake River Birds of Prey National Conservation Area in Idaho during the breeding seasons of 1991a??1994. Raptor counts on military training ranges did not differ when we compared all training days to all non-training days. However, during one period of intensive military training in one breeding season, raptor counts were lower during training than on non-training days. During training, Northern Harriers (Circus cyaneus) did not alter their behavior on training days. In years when prey numbers were low, falcons, hawks, and eagles perched and flew at low levels less often and flew at higher altitudes more often during training than they did when training did not occur. We observed fewer prey capture attempts on ranges on days with training than on days without training. Specific types of military training activity affected counts of raptors on ranges. The lowest raptor counts were associated with firing of artillery, small arms, and main turret guns or machine guns on tanks. Raptor counts associated with tank preparation (i.e., assembling and loading ammunition), driving, laser training, and convoy traffic were similar to non-training periods.

The Condor↗
USGS2003

Gyrfalcon diet in central west Greenland during the nestling period

We studied food habits of Gyrfalcons (Falco rusticolus) nesting in central west Greenland in 2000 and 2001 using three sources of data: time-lapse video (3 nests), prey remains (22 nests), and regurgitated pellets (19 nests). These sources provided different information describing the diet during the nesting period. Gyrfalcons relied heavily on Rock Ptarmigan (Lagopus mutus) and arctic hares (Lepus arcticus). Combined, these species contributed 79-91% of the total diet, depending on the data used. Passerines were the third most important group. Prey less common in the diet included waterfowl, arctic fox pups (Alopex lagopus), shorebirds, gulls, alcids, and falcons. All Rock Ptarmigan were adults, and all but one arctic hare were young of the year. Most passerines were fledglings. We observed two diet shifts, first from a preponderance of ptarmigan to hares in mid-June, and second to passerines in late June. The video-monitored Gyrfalcons consumed 94-110 kg of food per nest during the nestling period, higher than previously estimated. Using a combination of video, prey remains, and pellets was important to accurately document Gyrfalcon diet, and we strongly recommend using time-lapse video in future diet studies to identify biases in prey remains and pellet data.

The Condor↗
USGS2006

Are migrating raptors guided by a geomagnetic compass?

We tested whether routes of raptors migrating over areas with homogeneous topography follow constant geomagnetic courses more or less closely than constant geographical courses. We analysed the routes taken over land of 45 individual raptors tracked by satellite-based radiotelemetry: 25 peregrine falcons, Falco peregrinus, on autumn migration between North and South America, and seven honey buzzards, Pernis apivorus, and 13 ospreys, Pandion haliaetus, on autumn migration between Europe and Africa. Overall, migration directions showed a better agreement with constant geographical than constant geomagnetic courses. Tracks deviated significantly from constant geomagnetic courses, but were not significantly different from geographical courses. After we removed movements directed far from the mean direction, which may not be migratory movements, migration directions still showed a better agreement with constant geographical than constant geomagnetic courses, but the directions of honey buzzards and ospreys were not significantly different from constant geomagnetic courses either. That migration routes of raptors followed by satellite telemetry are in closer accordance with constant geographical compass courses than with constant geomagnetic compass courses may indicate that geographical (e.g. based on celestial cues) rather than magnetic compass mechanisms are of dominating importance for the birds' long-distance orientation.

Animal Behaviour↗
USGS2000

Scientific meeting raises awareness of amphibian decline in Asia

Blood samples from 433 Peregrine Falcons (Falco peregrinus) during fall and spring migrations, 1976-80, indicated that most of their pesticide burden, primarily DDE, was accumulated on wintering grounds in Latin America. DDE in spring migrants returning from Latin America for the first time declined significantly from 1979 to 1980. Only about 10% of breeding-age females contained organochlorine residues likely to adversely affect reproduction. The organochlorine pesticide threat in Latin America may be diminishing.

Newsletter of the Declining Amphibian Populations ↗
USGS1983

Organochlorine pesticides and PCB's: A continuing problem for the 1980s

In general. decreases in OC contamination in North America are unmistakable. This is documented by the NPMP. but. more importantly. it is borne out by improvements in the reproduction and population status of the brown pelican. bald eagle, peregrine falcon, and osprey. However, some OC contamination still persists, and several species, particularly predatory birds and insectivorous bats, continue to be vulnerable. Current OC problems in North America result from present and past usage and from industrial contamination. In addition, some studies suggest that some migrant bird species that winter south of the U.S. border are exposed to higher levels of OC pesticide than non-migrants. However, heavy OC pesticide contamination is known to exist in Arizona, New Mexico, and in southern California where migratory birds might stop during migration. At this time, we do not have the information to assess specifically the sources of contamination for most migrant species. From the number of recent OC problems identified in North America, it is apparent that OC's are not confined to the past and that we must continue to monitor and study OC's during this decade. However, current administrative, management, and research priorities are being directed toward the search for potential impacts of newer pesticides, air pollution. industrial waste, and other contaminants. Although it is necessary to build a body of scientific data on these types of contaminants, we feel that we cannot neglect continued work on OC's for which harmful effects impacting our wildlife resources are already known.

Transactions of the North American Wildlife and Na↗
USGS1990

Evidence for a fall raptor migration pathway across the South China Sea

While conducting seabird surveys along the cruise track of the Soviet oceanographic Research Vessel Akademlk Korolev in the South China Sea in late October, 1988, we encountered about 150 land birds, including about 40 raptors. Most of the raptors were small accipiters, but we also recorded small numbers of Peregrine Falcons (Falco peregrinus) and Oriental Scops Owls (Otus sunia). We saw most of the raptors during a 3-day period in a restricted area ca 350 km southeast of the southern tip of the Indo-China Peninsula. The observations suggest that a significant raptor migration corridor exists between Viet Nam and Borneo. The behavior and body condition of the diurnal raptors suggest that they were in good health and were making extensive use of the ship for perching, roosting, and hunting.

Journal of Raptor Research↗
USGS1995

Preliminary raptor surveys in western Mongolia

Raptors were observed on a 5200 km expedition from Ulaan Baatar through the Hangay Mountains to the Russian Altay Mountains with return through the Gobi Altay Mountains. The focus of the expedition was on nesting ecology of the Saker (Falco cherrug) and Altay falcons (F. altaicus) (25 eyries were located), but nests were also found for seven other species including more than 30 nests found of the upland buzzard (Buteo hemilasius). We conducted 21 day-long counts and 10 more formal raptor road counts. Raptors were concentrated in areas where perches were common and where food was most abundant. Western Mongolia remains a vast undeveloped land where camel trains and yak carts are normal. No developed highway network exists. Raptor work in the interior must be supported by four-wheel drive vehicles traveling cross country. Food and fuel for a research team are difficult to procure, but raptor populations are largely unexploited. Raptors frequently nest on the ground or on very low cliffs and tress, and often nest in close proximity of pairs of their own and other species. Several areas of special significance to raptors are discussed including the Taleen Ulaan (Red Steppe) areas of granite dells which we recommend for status as an international reserve.

Journal of Raptor Research↗
USGS1993

Telemetry via satellites for raptor studies

Monitoring animal movements by satellite was first ac complished in 1970 with an elk in Wyoming. The large size of early transmitter packages restricted their use to very large animals. Miniaturization of electronic components in the 1980s allowed application of satellite telemetry to large birds. Satellite transmitters have been tested with mixed results on geese, swans, petrels, bustards, eagles, and falcons. Dramatic weight reduction in the 1980s was quickly followed by tests of a variety of transmitter shapes on captive birds. Research on attachment methods helped in selecting those methods least likely to elicit adverse behavior. Wind tunnel experiments were conducted to produce more aerodynamically efficient PTT designs. Recently, the utility of satellite tracking has been demonstrated in studies of wandering albatrosses in the Indian Ocean, migrating Bewick's swans, bald eagles, and golden eagles. Two other studies demonstrated the feasibility of tracking cranes by satellite. The types of information from these techniques will be presented and cross-referenced to a poster display and demonstration.

Journal of Raptor Research↗
USGS1993

'Tool' use by the red-tailed hawk ( Buteo jamaicensis )

Perhaps the best documented example of regular tool use for a falconiform is the Egyptian Vulture ( Neophron percnopterus ) striking an Ostrich ( Struthio camelus ) egg with a stone (J. van Lawick-Goodall and H. van Lawick-Goodall 1966, Nature 212:1468-1469; R.K. Brooke 1979, Ostrich 50:257-258). Another species, the Lammergeier ( Gypaetus barbatus ), routinely drops bones on stone slabs to gain access to the marrow within (L. Brown and D Amadon 1968, Eagles, hawks and falcons of the world, McGraw-Hill, New York, NY U.S.A.). Some, however, would argue that, because the stone is not manipulated, the bone-dropping Lammergeier is not actually using a tool. Another reported example of tool use is the Ferruginous Hawk ( Buteo regalis ) that allegedly cast a stone at a human intruder near its nest (C.L. Blair 1981, Raptor Research 15:120).] The following may be yet another example of tool use by a raptor. On 5 June 1985, we observed an adult Red-tailed Hawk ( Buteo jamaicensis ) soaring low (ca 15 m) over the grass-covered slopes of the Galiuro Mountains in southern Arizona. The bird had, probably just moments before, captured a ca I m snake (probably a glossy snake, Arizona elegans , judging by size, shape and color). When the hawk passed near us, it was holding the snake by both feet near the snake's midpoint. With head elevated and mouth open, the snake appeared intent upon biting the hawk. When the hawk was ca 100 m distant from us, it made several shallow stoops over a scattered group of large boulders. On some (and perhaps all) passes, the bird swept sharply upward as it passed over and nearly collided with a boulder. The centrifugal force associated with this change in direction caused the snake to pendulate below the hawk's talons and strike the boulder. During one pass, we observed the snake's head and tail flipping up behind the hawk after slapping the boulder. Not all swoops were over the same boulder, but one particularly obtrusive (ca 1 m tall) boulder was used at least twice. On the last two swoops, the snake hung limp and apparently lifeless from the hawk's talons After the last swoop, the hawk dropped out of sight into tall grass ca 200 m from our position and presumably ate the snake because we could observe no prey in the hawk's talons when it soared up 13 rain later. If the anvil (not held in the hand) is a tool as well as the hammer (held in the hand), then the Red-tailed Hawk may be added to the short list of raptors that have been known to use tools

Arizona↗
USGS1999

Trash-caused mortality in Mongolian raptors

On four expeditions (1994, 1995, 1997, and 1998) through Mongolia, we found two kinds of mortality associated with trash gathered by parent raptors as part of the nest building process. Our observations of actual mortality were limited to three species: the golden eagle (Aquila chrysaetos) (2 clutches of eggs), the saker falcon (Falco cherrug) (4 nestlings), and the upland buzzard (Buteo hemilasius) (1 nestling); all from the eastern half of Mongolia.

Ambio↗
USGS1995

Residues and trends of organochlorine pesticide and polychlorinated biphenyls in birds from Texas, 1965-88

Concentrations of DDE (a metabolite of DDT) in birds decreased during recent years in most areas of the continental United States. Organochlorine pesticides were widely used in agriculture in Texas from the early 1950s to the 1970s. I used previously published data to determine whether concentrations of DDE and polychlorinated biphenyls (PCBs) in birds from Texas have followed a decreasing trend similar to that in birds from other areas in the United States. A total of 2,669 bird samples was collected between 1965 and 1988 from diverse locations in Texas and was analyzed for organochlorines and other environmental contaminants. The brown pelican ( Pelecanus occidentalis ), peregrine falcon ( Falco peregrinus ), laughing gull ( Larus atricilla ), black skimmer ( Rynchops niger ), and European starling ( Sturnus vulgaris ) were the most frequently studied species. DDE and PCBs were the most commonly detected organochlorines in bird tissues. Mean DDE concentrations ranged from 0.4 to 61.00 parts per million (ppm) wet weight (ww) and PCBs from 0.02 to 32.00 ppm ww. Concentrations of DDE in eggs and carcasses of black skimmers decreased significantly during 1970-84 and dropped from approximately 10 to nearly 3 ppm ww. PCBs decreased from approximately 7 ppm ww to 1 ppm ww in eggs and carcasses. DDE concentrations in eggs of brown pelicans varied from more than 3 ppm ww in 1970 to approximately 1 ppm ww in 1983; and PCB concentrations diminished from about 10 to 1 ppm ww. Decreasing trends in concentrations of DDE and PBCs were observed in most species, although in some cases, the estimated trends were not significantly different from zero. Concentrations of DDE in birds from the Texas coast decreased from more than 6.0 ppm in 1978 to below 0.5 ppm in 1985. The decreasing ratios in selected species varied from approximately 2.0 to 12.0 (DDE) and from 4.5 to 9.0 (PCBs). The results indicate that in general from 1965 to 1988, DDE and PCBs declined in birds from Texas.

Texas↗
USGS2003

Gyrfalcon diet in central west Greenland during the nesting period

We studied food habits of Gyrfalcons (Falco rusticolus) nesting in central west Greenland in 2000 and 2001 using three sources of data: time-lapse video (3 nests), prey remains (22 nests), and regurgitated pellets (19 nests). These sources provided different information describing the diet during the nesting period. Gyrfalcons relied heavily on Rock Ptarmigan (Lagopus mutus) and arctic hares (Lepus arcticus). Combined, these species contributed 79-91% of the total diet, depending on the data used. Passerines were the third most important group. Prey less common in the diet included waterfowl, arctic fox pups (Alopex lagopus), shorebirds, gulls, alcids, and falcons. All Rock Ptarmigan were adults, and all but one arctic hare were young of the year. Most passerines were fledglings. We observed two diet shifts, first from a preponderance of ptarmigan to hares in mid-June, and second to passerines in late June. The video-monitored Gyrfalcons consumed 94-110 kg of food per nest during the nestling period, higher than previously estimated. Using a combination of video, prey remains, and pellets was important to accurately document Gyrfalcon diet, and we strongly recommend using time-lapse video in future diet studies to identify biases in prey remains and pellet data.

Condor↗