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Geology topics

G.W. Pendleton

Publications and source records attributed to G.W. Pendleton.

32 records · Page 2Linked to original sources
USGS1992

Determination of hatching date for eggs of black-crowned night-herons, snowy egrets and great egrets

Floatation of eggs in water and specific gravity of eggs of Black-crowned Night-Herons (Nycticorax nycticorax ), Snowy Egrets (Egretta thula ) and Great Egrets (Casmerodius albus ) were evaluated as methods to determine date of hatching. Although specific gravity was a better predictor of hatching date than egg flotation, both techniques were imprecise. The regression between specific gravity and the number of days before hatching differed among clutches, but not among eggs within clutches. Specific gravity of eggs predicted hatching date only to within 3.8 d for Snowy Egrets, and 4.7 d for Black-crowned Night-Herons and Great Egrets. The mean incubation period was 27.3 d for Great Egrets, 23.7 d for Snowy Egrets and 22.8 d for Black-crowned Night- Herons. For all three species, the A egg (first egg laid) had a longer incubation period than the B or C egg.

Journal of Field Ornithology↗
USGS1992

Black duck population units as determined by patterns of band recovery

To estimate regional survival and band recovery rates for waterfowl populations, banding sites must be grouped for data analysis. We group American black duck banding sites using cluster analysis of pairwise comparisons of the distributions of band recoveries. We propose 6 population units, substantially fewer than the 27 black duck reference areas currently used. Flyways do not seem to reflect the population affInities of black ducks.

Book chapter↗
USGS1992

Effects of extended photoperiod on sandhill crane reproduction

Photoperiod studies were conducted with greater sandhill cranes (Grus canadensis tabida) from 1969 to 1972 and from 1982 to 1987 at the Patuxent Wildlife Research Center, Maryland. When housed indoors and exposed to long photoperiods, males produced semen during winter. When exposed to artificially extended photoperiods during spring in outdoor pens, females apparently laid earlier in the year and laid more eggs than they would have without the added light. Cranes did not exhibit any signs of photorefractory response to extended photoperiods.

Book chapter↗
USGS1992

Determination of hatching date for eggs of black-crowned night-herons, snowy egrets and great egrets

Flotation of eggs in water and specific gravity of eggs of Black-crowned Night-Herons (Nycticorax nycticorax), Snowy Egrets (Egretta thula) and Great Egrets (Casmerodius albus) were evaluated as methods to determine date of hatching. Length of incubation and duration of hatching period were also documented for each species. Although species gravity was a better predictor of hatching date than egg flotation, both techniques were imprecise. The regression between specific gravity and the number of days before hatching differed among clutches, but not among eggs within clutches. Specific gravity of eggs predicted hatching data only to within 3.8 d for Snowy Egrets, adn 4.7 d for Black-crowned Night-Herons and Great Egrets. The mean incubation period was 27.3 d for Great Egrets, 23.7 d for Snowy Egrets and 22.8 d for Black-crowned Night-Herons. For all three species, the A egg (first egg laid) had a longer incubation period than the B or C egg. For all three species, the number of days between hatching of A and B eggs was significantly less (median - 1 d) than between hatching of B and C eggs (median = 2 d).

Journal of Field Ornithology↗
USGS1992

Distribution and color variation of gyrfalcons in Russia

Gyrfalcon (Falco rusticolus) museum specimens in Moscow (73) and St. Petersburg (132) were divided into four color classes (gray, light gray, white gray, and white) and four longitudinal belts representing major physiographic regions of northern Russia. Gray variants predominated in the west and central regions. White birds were most common in extreme eastern Siberia, but were occasionally found even west of the Ural Mountains. Frequencies were as follows: European Russia 4% white, 50% gray (the remainder were intermediates); western Siberia 0% white, 58% gray; central Siberia 15% white, 42% gray; and eastern Siberia 47% white, 33% gray. Remarkably, in the easternmost subregion, white birds predominated even near the southernmost extension. Because the northernmost portions of the species' range in continental Russia are in central Siberia where white variants were rare, we propose that a better predictor of the white variant is longitude, not latitude. White birds were most frequent at the eastern reaches of both the Palearctic and Nearctic. The best environmental correlates of this distribution pattern may be the southward bending thermal isoclines proceeding eastward toward Greenland or Kamchatka, where both land masses are bathed by cold oceanic currents of Arctic origin. By contrast, the western reaches of both land masses are bathed by warm currents. In these western reaches, Gyrfalcon summer distribution is displaced northward and dark variants predominate. The breeding range of the Gyrfalcon, determined by mapping the locations of the specimens we examined, differs little from the range proposed in 1951.

Journal of Raptor Research↗
USGS1991

Effects of dietary boron and arsenic on the behavior of mallard ducklings

High concentrations of boron and arsenic have been associated with irrigation drain water and aquatic plants consumed by waterfowl. Both compounds affect the central nervous system and cause generalized physiological distress in mammals and waterfowl. We examined sublethal effects of boron and arsenic on the behavior of developing mallard ducklings (Anas platyrhynchos). Day-old ducklings received an untreated diet (control) or a diet containing 100, 400, or 1,600 ppm boron, added as boric acid, or 30, 100, or 300 ppm arsenic, added as sodium arsenate. Activity schedules and behavior durations were analyzed for effects at the various treatment levels. Both boron and arsenic at the highest levels had significant effects on the activity schedules of developing ducklings, including increased time at rest and under the provided heat lamp. We also observed decreases in the amount of time treated ducklings spent in alert behaviors and in the water in comparison to control ducklings. High levels of boron (1,600 ppm) increased feeding time overall but did not increase the amount of food consumed. Arsenic had no effect on feeding behavior. There were no differences found in the durations of behaviors as a result of treatment. These findings, in combination with reported effects on the growth and physiology of ducklings under identical treatments, suggest that reported concentrations of these compounds in aquatic plants in the Central Valley of California could adversely affect normal duckling development and survival.

Environmental Toxicology and Chemistry↗
USGS1991

Interactive effects of boron, selenium, and dietary protein on survival, growth and physiology in mallard ducklings

High concentrations of boron (B) and selenium (Se) have been found in aquatic food chains associated with irrigation drainwater. Total biomass of invertebrates, a major source of protein for wild ducklings, is sometimes diminished in agricultural drainwater ponds contaminated with Se and B. Day-old mallard ( Anas platyrhynchos ) ducklings received an untreated diet (controls) containing 22% protein or diets containing 15 ppm (μg/g) Se (as selenomethionine), 60 ppm Se, 1,000 ppm B (as boric acid), 15 ppm Se with 1,000 ppm B, or 60 ppm Se with 1,000 ppm B. In a concurrent experiment, the above sequence was repeated with a protein-restricted (7%) but isocaloric diet. After four weeks, blood and tissue samples were collected for biochemical and histological examination. With 22% protein and 60 ppm Se in the diet, duckling survival and growth was reduced and histopathological lesions of the liver occurred. Boron alone caused some reduction in growth. Several interactive effects occurred between B and Se, including further reduction in growth, and increases in plasma glutathione reductase activity, hematocrit, hemoglobin and plasma protein concentrations. With 7% protein, the growth of controls was less than that with 22% protein, 60 ppm Se caused 100% mortality, and growth effects of 15 ppm Se and 1,000 ppm B alone were more pronounced than with 22% protein. Selenium accumulation increased in the liver with 7% protein. Interactive effects were greater for Se and B with 7% protein than with 22% protein and included significant mortality and enhanced accumulation of Se in the liver. These findings suggest the potential for more severe toxicological effects of Se and B independently and interactively on duckling survival and development when dietary protein is diminished.

Archives of Environmental Contamination and Toxico↗
USGS1991

Movements and survival of American black duck and mallard broods on Chesapeake Bay

We attached radio transmitters to day-old American black duck (Anas rubripes) and mallard (A. platyrhynchos) ducklings and monitored duckling habitat use, brood movements, and survival rates for 30 days. Ducklings moved an average of 2.3 km within the first 24 hours and another 1.5 km thereafter. After the initial move, broods usually moved once more. No differences in initial movement distance, subsequent movement distance, or total number of movements were found between black duck and mallard broods. There was some evidence that broods in more human developed areas moved more than broods in less human-developed areas. Black duck duckling survival rates were greater than mallard survival rates in 1 of 2 study years.

Chesapeake Bay↗
USGS1990

Effects of arsenate on growth and physiology in mallard ducklings

Arsenic (As) has been found at elevated concentrations in irrigation drainwater and in aquatic plants utilized by waterfowl. Mallard ( Anas platyrhynchos ) ducklings received an untreated diet (controls) or diets containing 30, 100 or 300 ppm As added as sodium arsenate. After 10 weeks blood and tissue samples were collected for biochemical and histological examination. Arsenic accumulated significantly in brain and liver of ducklings fed 100 or 300 ppm but did not result in histopathological lesions. The 300-ppm dietary As concentration decreased overall growth (weight gain) in males, whereas all concentrations of As decreased overall growth and rate of growth in females. Food consumption was less during the first three weeks in the 300-ppm group and during the second week for the 100-ppm group compared to controls. Plasma sorbitol dehydrogenase activity and plasma glucose concentration were higher in the 300-ppm group compared to controls. Plasma triglyceride concentration increased in all As-treated groups. Brain ATP was lower in the 300-ppm group and sodium/potassium-dependent ATPase activity was higher in the 30- and 100-ppm groups. Hepatic glutathione peroxidase activity was lower in the 300-ppm group and malondialdehyde lower in all treatment groups. All treatment levels caused elevation in hepatic glutathione and ATP concentrations. These findings, in combination with altered duckling behavior (increased resting time), suggest that concentrations of As that have been found in aquatic plants (up to 430 ppm dry weight) could adversely affect normal duckling development.

Environmental Toxicology and Chemistry↗
USGS1990

Effects of boron on growth and physiology in mallard ducklings

High concentrations of boron (B) have been associated with irrigation drainwater and aquatic plants consumed by waterfowl. Day-old mallard ( Anas platyrhynchos ) ducklings received an untreated diet (controls) or diets containing 100, 400 or 1,600 ppm B as boric acid. Survival, growth and food consumption were measured for 10 weeks. At termination, blood and tissue samples were collected for biochemical assays and histological examination. The highest dietary concentration of B caused 10% mortality, decreased overall growth and the rate of growth (sexes combined), whereas lower concentrations of B altered growth only in females. Food consumption was lower during the first 3 weeks in the 1,600-ppm group and during the second week in all B-treated groups compared to controls. Hematocrit and hemoglobin were lower and plasma calcium concentration higher in the 1,600-ppm group compared to controls. Plasma triglyceride concentration was elevated in all B-treated groups. Brain B concentration increased to 25 times that of controls in the 1,600-ppm group. Brain ATP decreased with increasing dietary B. Brain acetylcholinesterase activity and total ATPase activity (in males) were elevated and protein concentration lowered in the 1,600-ppm group. Boron accumulated less in the liver than in the brain but resulted in an initial elevation of hepatic glutathione. These findings, in combination with altered duckling behavior, suggest that concentrations of B occurring in aquatic plants could adversely affect normal duckling development.

Environmental Toxicology and Chemistry↗
USGS1990

Fat scoring: Sources of variability

Fat scoring is a widely used nondestructive method of assessing total body fat in birds. This method has not been rigorously investigated. We investigated inter- and intraobserver variability in scoring as well as the predictive ability of fat scoring using five species of passerines. Between-observer variation in scoring was variable and great at times. Observers did not consistently score species higher or lower relative to other observers nor did they always score birds with more total body fat higher. We found that within-observer variation was acceptable but was dependent on the species being scored. The precision of fat scoring was species-specific and for most species, fat scores accounted for less than 50% of the variation in true total body fat. Overall, we would describe fat scoring as a fairly precise method of indexing total body fat but with limited reliability among observers.

Condor↗
USGS1989

Statistical considerations in designing raptor surveys

Careful sampling design is required to obtain useful estimates of raptor abundance. Well-defined objectives, selection of appropriate sample units and sampling scheme, and attention to detail to reduce extraneous sources of variability and error are all important considerations in designing a raptor survey.

Book chapter↗
USGS1988

Multivariate curve-fitting in GAUSS

Multivariate curve-fitting techniques for repeated measures have been developed and an interactive program has been written in GAUSS. The program implements not only the one-factor design described in Morrison (1967) but also includes pairwise comparisons of curves and rates, a two-factor design, and other options. Strategies for selecting the appropriate degree for the polynomial are provided. The methods and program are illustrated with data from studies of the effects of environmental contaminants on ducklings, nesting kestrels and quail.

American Statistical Association, Proceedings of t↗