Geology topics
Publications and source records attributed to P.H. Albers.
Effect on mallard embryos of eggshell applications of varying amounts of No. 2 fuel oil, South Louisiana crude oil, Kuwait crude oil, and a paraffin mixture. Measured survival and hatching weight.
Habitat preferences of breeding Red-winged Blackbirds in an agricultural area were determined by comparing population density, landscape characteristics, and vegetational descriptions. Observations were made throughout the breeding season. Preferred breeding habitats of Red-wings, in order of preference, were wetlands, hayfields, old fields, and pastures. Males and females occupied old fields and wetlands first, then hayfields, and finally, pastures. Cutting of hayfields caused territorial abandonment by both sexes within 48 h. The apparent movement of displaced females from cut hayfields to uncut hayfields suggests that habitat fidelity of females is strong after the breeding effort has begun. Breeding Red-wings exhibited general preferences for trees, large amounts of habitat edge, erect old vegetation, and sturdy, tall, and dense vegetation. Vegetative forms and species, such as upland grasses, broad- and narrow-leafed monocots in wetlands, and forbs were important to the Red-wing at various times during the breeding season. Landscape and vegetational preferences of breeding adults were easier to observe early in the breeding season (March through May) than later. Vegetational growth and increases in the size of the breeding population probably make these preferences more difficult to detect. Territory size was poorly correlated with landscape and vegetational characteristics in uplands but strongly correlated with broad- and narrow-leafed mono cots and vegetative height in wetlands. Wetland territories were smaller than upland territories. Territories increased in size during the middle and late portions of the breedi g season. Habitat selection by the Red-winged Blackbird can best be studied by evaluating vegetative preferences throughout the breeding season.
An experiment was performed to determine the toxicity of oil to incubating eggs. Number 2 fuel oil, a mixture of 9 paraffin compounds, and propylene glycol were applied to the surface of artificially incubated mallard ( Anas platyrhynchos ) eggs. Seven groups of 50 eggs each were treated with 1, 5, 10, 20, and 50 μl of fuel oil, 50 μ1 of the paraffin mixture, and 50 μl of propylene glycol. Fifty untreated eggs served as a control. Microliter syringes were used to apply the liquid around the air cell end of the egg on the 8th day of incubation. Embryonic mortality was significantly greater (P ≤ 0.01) in all oil treated groups and the paraffin mixture group than in the control group. Most of the embryonic mortality for the oiled eggs occurred within 72 hours of treatment. Hatching and post-hatching (4 weeks) weights of the ducklings in all treatment groups were not significantly different (P > 0.01) from the control. Thus, the transfer of even small quantities of oil to the egg surface is sufficient to reduce hatchability.
Because eggs of marine birds may be exposed to oil adhering to the feathers of adult birds, a study was undertaken to determine the effects of oil contamination. Two hundred common eider eggs were divided into four experimental sets of 50 each. Two sets were treated with No. 2 fuel oil in amounts of 5 microliters to 20 microliters; a third with 20 microliters of propylene glycol, a neutral blocking agent. The fourth set served as a control. Hatching success was 96 percent for the eggs treated with 20 microliters propylene glycol, 96 percent for the controls and 92 percent for the eggs treated with 5 microliters oil hatched. Only 69 percent of the eggs treated with 20 microliters of oil survived - a significant reduction in hatchability (P 0.05). Mean Hatching weights for all sets were statistically equal. Thus, oil pollution may significantly increase embryonic mortality in marine birds.
There is some evidence of the impact of direct mortality from oil spills on bird populations, but very little is known about the sublethal and indirect effects of oil on birds. Research at the Patuxent Wildlife Research Center, Laurel, Maryland, is directed at (1) determining the effects of petroleum on the physiology and reproductive success of birds, and (2) developing the analytical methodology necessary for detection of petroleum in avian tissues.
Population sizes of territorial male red-winged blackbirds ( Agelaius phoeniceus ) were determined with counts of territorial males (area count) and a Petersen-Lincoln Index method for roadsides (roadside estimate). Weather conditions and time of day did not influence either method. Combined roadside estimates had smaller error bounds than the individual transect estimates and were not hindered by the problem of zero recaptures. Roadside estimates were usually one-half as large as the area counts, presumably due to an observer bias for marked birds. The roadside estimate provides only an index of major changes in populations of territorial male redwings. When the roadside estimate is employed, the area count should be used to determine the amount and nature of observer bias. For small population surveys, the area count is probably more reliable and accurate than the roadside estimate.
Explore the source record for details and available documents.