Geology topics

C.A. Kelly

Publications and source records attributed to C.A. Kelly.

3 recordsLinked to original sources

USGS2016

Predictive habitat models derived from nest-box occupancy for the endangered Carolina northern flying squirrel in the southern Appalachians

In the southern Appalachians, artificial nest-boxes are used to survey for the endangered Carolina northern flying squirrel (CNFS; Glaucomys sabrinus coloratus ), a disjunct subspecies associated with high elevation (>1385 m) forests. Using environmental parameters diagnostic of squirrel habitat, we created 35 a priori occupancy models in the program PRESENCE for boxes surveyed in western North Carolina, 1996-2011. Our best approximating model showed CNFS denning associated with sheltered landforms and montane conifers, primarily red spruce Picea rubens . As sheltering decreased, decreasing distance to conifers was important. Area with a high probability (>0.5) of occupancy was distributed over 18662 ha of habitat, mostly across 10 mountain ranges. Because nest-box surveys underrepresented areas >1750 m and CNFS forage in conifers, we combined areas of high occupancy with conifer GIS coverages to create an additional distribution model of likely habitat. Regionally, above 1385 m, we determined that 31795 ha could be occupied by CNFS. Known occupied patches ranged from

North Carolina, Tennessee, Virginia↗

USGS2007

Whole-ecosystem study shows rapid fish-mercury response to changes in mercury deposition

Methylmercury contamination of fisheries from centuries of industrial atmospheric emissions negatively impacts humans and wild-life worldwide. The response of fish methylmercury concentrations to changes in mercury deposition has been difficult to establish because sediments/soils contain large pools of historical contamination, and many factors in addition to deposition affect fish mercury. To test directly the response of fish contamination to changing mercury deposition, we conducted a whole-ecosystem experiment, increasing the mercury load to a lake and its watershed by the addition of enriched stable mercury isotopes. The isotopes allowed us to distinguish between experimentally applied mercury and mercury already present in the ecosystem and to examine bioaccumulation of mercury deposited to different parts of the watershed. Fish methylmercury concentrations responded rapidly to changes in mercury deposition over the first 3 years of study. Essentially all of the increase in fish methylmercury concentrations came from mercury deposited directly to the lake surface. In contrast, <1% of the mercury isotope deposited to the watershed was exported to the lake. Steady state was not reached within 3 years. Lake mercury isotope concentrations were still rising in lake biota, and watershed mercury isotope exports to the lake were increasing slowly. Therefore, we predict that mercury emissions reductions will yield rapid (years) reductions in fish methylmercury concentrations and will yield concomitant reductions in risk. However, a full response will be delayed by the gradual export of mercury stored in watersheds. The rate of response will vary among lakes depending on the relative surface areas of water and watershed.

Proceedings of the National Academy of Sciences of↗

USGS2002

Accessible habitat for shorebirds: Factors influencing its availability and conservation implications

We examined the relationship between water levels and accessible habitat, and how accessible habitat influenced Dunlin (Calidris alpina) and Semipalmated Sandpiper (Calidris pusilla) numbers in managed wetlands at Pea Island (North Carolina) and Merritt Island (Florida) National Wildlife Refuges in 1998 and 1999. At Pea Island we experimentally manipulated water levels, which also allowed us to examine the effects of water level fluctuations on prey base. We examined these relationships because access to foraging habitat by shorebirds is positively related to the length of their tarsometatarsus, and in the southeastern United States, small calidrids are a numerically important component of the two million migrants using inland and managed wetlands. We confirmed the importance of shallow waters for Dunlin and Semipalmated Sandpiper-numbers increased with increasing availability of 0-4 cm habitat. At Merritt Island, Dunlin use was inversely related to variability in water depth of 0-4 cm. Minimizing the frequency and amplitude of water level fluctuations associated with single-capped culverts is necessary to improve habitat quality. After adjusting for accessibility, spring habitat requirements for Dunlin and Semipalmated Sandpiper at Pea Island were met under nearly all abundance scenarios. We identified water level targets that maximize accessible habitat at Pea Island. In contrast, winter habitat requirements for Dunlin at Merritt Island were not met except in one scenario. Seasonally low prey density contributed to the shortfall, suggesting that allocating more habitat is the primary management option. Manipulating water levels at Pea Island did not adversely affect the density of eight shorebird prey species. Estimates of accessible habitat and other parameters (e.g., turnover rates, prey biomass) are essential to set and implement realistic shorebird habitat conservation goals.

Waterbirds↗