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J. A. Johnson

Publications and source records attributed to J. A. Johnson.

13 recordsLinked to original sources
USGS2008

Long-term survival despite low genetic diversity in the critically endangered Madagascar fish-eagle

The critically endangered Madagascar fish-eagle (Haliaeetus vociferoides) is considered to be one of the rarest birds of prey globally and at significant risk of extinction. In the most recent census, only 222 adult individuals were recorded with an estimated total breeding population of no more than 100-120 pairs. Here, levels of Madagascar fish-eagle population genetic diversity based on 47 microsatellite loci were compared with its sister species, the African fish-eagle (Haliaeetus vocifer), and 16 of these loci were also characterized in the white-tailed eagle (Haliaeetus albicilla) and the bald eagle (Haliaeetus leucocephalus). Overall, extremely low genetic diversity was observed in the Madagascar fish-eagle compared to other surveyed Haliaeetus species. Determining whether this low diversity is the result of a recent bottleneck or a more historic event has important implications for their conservation. Using a Bayesian coalescent-based method, we show that Madagascar fish-eagles have maintained a small effective population size for hundreds to thousands of years and that its low level of neutral genetic diversity is not the result of a recent bottleneck. Therefore, efforts made to prevent Madagascar fish-eagle extinction should place high priority on maintenance of habitat requirements and reducing direct and indirect human persecution. Given the current rate of deforestation in Madagascar, we further recommend that the population be expanded to occupy a larger geographical distribution. This will help the population persist when exposed to stochastic factors (e.g. climate and disease) that may threaten a species consisting of only 200 adult individuals while inhabiting a rapidly changing landscape. ?? 2008 The Authors.

Molecular Ecology↗
USGS2007

Shorebird abundance and distribution on the coastal plain of the Arctic National Wildlife Refuge

The coastal plain of the Arctic National Wildlife Refuge hosts seven species of migratory shorebirds listed as highly imperiled or high priority by the U.S. Shorebird Conservation Plan and five species listed as Birds of Conservation Concern by the U.S. Fish and Wildlife Service. During the first comprehensive shorebird survey of the 674 000 ha "1002 Area" on the coastal plain, we recorded 14 species of breeding shorebirds at 197 rapidly surveyed plots during June 2002 and 2004. We also estimated detection ratios with a double counting technique, using data collected at 37 intensively studied plots located on the North Slope of Alaska and northern Canada. We stratified the study area by major habitat types, including wetlands, moist areas, uplands, and riparian areas, using previously classified Landsat imagery. We developed population estimates with confidence limits by species, and estimated the total number of shorebirds in the study area to be 230 000 (95% CI: 104 000-363 000), which exceeds the biological criterion for classification as both a Western Hemisphere Shorebird Reserve Network Site of International Importance (100 000 birds) and a Ramsar Wetland of International Importance (20 000 birds), even when conservatively estimated. Species richness and the density of many species were highest in wetland or riparian habitats, which are clustered along the coast. ?? The Cooper Ornithological Society 2007.

Condor↗
USGS1994

Water Resources Data, California, Water Year 1993. Volume 5. Ground-Water Data

Water resources data for the 1993 water year for California consist of records of stage, discharge, and water quality of streams; stage and contents in lakes and reservoirs; and water levels and water quality in wells. This volume of the report series includes records on ground water in California. Additional ground-water information for California is contained in the files, data bases, and other published reports of the U.S. Geological Survey.

California↗
USGS1993

Streamflow and selected precipitation data for Yucca Mountain and vicinity, Nye County, Nevada, water years 1983-85

Streamflow and precipitation data collected at and near Yucca Mountain, Nevada, during water years 1983-85, are presented. The data were collected and compiled as part of the studies the U.S. Geological Survey is making, in cooperation with the U.S. Department of Energy, to characterize surface water hydrology in the Yucca Mountain area. Streamflow data include daily mean discharges and peak discharges at 4 complete-record gaging stations and peak discharges at 10 crest-stage, partial-record stations and 12 miscellaneous sites. Precipitation data include cumulative totals at 12 stations maintained by the U.S. Geological Survey and daily totals at 17 stations maintained by the Weather Service Nuclear Support Office, National Oceanic and Atmospheric Administration.

Open-File Report↗
USGS1993

Water Resources Data, California, Water Year 1992. Volume 5. Ground-Water Data

Water resources data for the 1992 water year for California consist of records of stage, discharge, and water.quality of streams; stage and contents in lakes and reservoirs; and water levels and water quality in wells. This volume of the report series includes records on ground water in California. Additional ground-water information for California is contained in the files, data bases, and other published reports of the U.S. Geological Survey.

California↗
USGS1992

Water Resources Data, California, Water Year 1991. Volume 5. Ground-Water Data

Water resources data for the 1991 water year for California consist of records of stage, discharge, and water quality of streams; stage and contents in lakes and reservoirs; and water levels and water quality in wells. Volume 5 contains water levels for 1,069 observation wells and water-quality data for 276 monitoring wells and 2 springs. These data represent that part of the National Water Data System opera?ted by the U.S. Geological Survey and cooperating State and Federal agencies in California.

California↗
USGS1991

Water Resources Data, California, Water Year 1990. Volume 5. Ground-Water Data

Water resources data for the 1990 water year for California consist of records of stage, discharge, and water quality of streams; stage and contents in lakes and reservoirs; and water levels and water quality in wells. Volume 5 contains water levels for 989 observation wells and water-quality data for 204 monitoring wells and 2 springs. These data represent that part of the National lvater Data System operated by the u.s. Geological Survey and cooperating State and Federal agencies in California.

California↗
USGS1990

Water Resources Data, California, Water Year 1989. Volume 5. Ground-Water Data

Water resources data for the 1989 water year for California consist of records of stage, discharge, and water quality of streams; stage and contents in lakes and reservoirs; and water levels and water quality in weils. Volume 5 contains water levels for 1,037 observation wells and water-quality data for 254 monitoring wells. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperatine State and Federal agencies in California.

California↗