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Research about Maryland, Virginia

Source-linked reports with geographic coverage including Maryland, Virginia.

117 records · Page 7Linked to original sources
USGS1978

An evaluation of errors in mapping land use changes for the Central Atlantic Regional Ecological Test Site

Land use change maps prepared from high-resolution, high-altitude aerial photographs for the period 1970 to 1972 of the CARETS (Central Atlantic Regional Ecological Test Site) project were analyzed for accuracy. To test for errors of commission, all outlined areas (polygons) of land use change on five l:100000-scale maps were examined for accuracy. An estimate of the errors of omission was obtained by comparing the land use change polygons mapped for the Norfolk SMSA (Norfolk and Virginia Beach Standard Metropolitan Statistical Area) with the changes mapped in a more detailed study of the same area. The results of these studies showed that the largest number of errors was caused by misregistration of the land use change map to the 1970 land use map; however, only a very small percentage of the total land area of the land use change was affected by misregistration. In the Norfolk SMSA, which is an area of rapid urban growth, many of the land use changes had not been mapped. The conclusion is that quality control checks are necessary both during and after map compilation. The experience of the CARETS and other land use mapping experiments conducted in the early 1970's has resulted in the development of carefully designed quality-control procedures implemented in the nationwide mapping of land use and land cover currently being carried out by the U.S. Geological Survey.

Maryland, Virginia↗
USGS1976

Infection and mortality in captive wild-trapped canvasback ducks

Fungal, bacterial and malarial infections, as well as malnutrition caused heavy mortality in a group of wild-trapped canvasbacks ( Aythya valisineria ) held in 10 × 3 × 2 m open water pens. Deaths occurred between 21 and 158 days after confinement and were associated with infections of Aspergillus fumigatus , Escherichia coli , Staphylococcus sp., Streptococcus sp., Klebsiella sp., Enterobacter sp., and Plasmodium sp. Infection and mortality was believed to result from reduced resistance associated with confinement. Fourteen canvasbacks released onto large ponds survived throughout the period during which the penned birds died.

Maryland, Virginia↗
USGS1976

Sediment-filled pots in upland gravels of Maryland and Virginia

Pot-shaped depressions filled with sandy clayey silt are found in "Upland" gravels (previously termed Brandywine) of probable Miocene age, in northeastern Maryland and in Virginia near Washington, D.C. The pots are about 7 ft (2m) deep and commonly are about as wide. In plan, many are strongly elliptical. Sides are steep or even bulbous, and the filling in some pots shows faint stratification paralleling the sides. Strata in the enclosing gravel commonly bend downward and are thinner beside and below the pots. The gravel deposits are remnants of alluvial deposits of the ancestral Susquehanna and Potomac Rivers. All the pots are at the present gravel surface. We suggest that the pots originated when seasonal frost in an overlying layer of sandy clayey silt provided a confining upper layer. The freezing plane in the silt moved downward, reaching the gravel at some points before others. Water in the gravel moved toward the freezing plane by capillarity or by cryostatic head, forming ice lenses in the silt. Each winter, ice growth forced unfrozen clayey silt a short distance downward and outward into the gravel, increasing the irregularity of the silt-gravel contact and promoting more rapid movement. The pots probably reflect some centuries of growth, probably during the Illinoian Glaciation.

Maryland, Virginia↗
USGS1974

The 1973 distribution and abundance of breeding ospreys in the Chesapeake Bay

An aerial survey in association with several intensive ground surveys yielded the first estimate of the size of the osprey ( Pandion haliaetus carolinensis ) nesting population in Chesapeake Bay. The 1973 population was estimated at 1,450 ± 30 pairs, of which 713 were on the western shore and 737 on the eastern shore. A small percentage of nonbreeders (possibly 2-5 percent) may be included in this estimate. Only 31.7 percent of the population was nesting in trees; the remaining birds utilized duck blinds (28.7 percent), channel markers (21.8 percent), and miscellaneous man-made structures (17.8 percent). The geographical distribution of nesting ospreys has quite likely changed during the last several decades as suitable artificial nesting sites have become more available. Furthermore, limited evidence suggests that birds nesting on the man-made sites were more successful than those nesting in trees. This study provides a basis for monitoring future changes in numbers and distribution.

Maryland, Virginia↗
USGS1973

Salmonellosis in passerine birds in Maryland and West Virginia

Salmonella typhimurium was responsible for a die-off of evening grosbeaks ( Hesperiphona vespertina ) at Elkins, West Virginia, and was isolated from a pine siskin ( Spinus pinus ) collected at the site of a die-off near Baltimore, Maryland.

Maryland, Virginia↗