Publications

Under the pressure of increasing human populations and expanding demands for food and fiber, native tropical and temperate habitats are becoming more restricted, and populations of many resident and migratory birds are declining. Mist net surveys of 111 forest and agricultural sites in Mexico, Belize, and Guatemala show that some migratory species use a wide variety of habitats during...

Faced with the problem of habitat loss and with the need to preserve the remaining components of the original avian biodiversity in neotropical regions such as Los Tuxtlas, it is imperative to determine how the neotropical migrant bird species have responded to the anthropogenic alterations of their natural habitats. To provide data in this direction, we censused neotropical migrant...

The study investigated the utility of Landsat TM data applied to produce geo-referenced habitat maps for two study areas (Toledo and Stann Creek). Locational and non-site-specific map accuracy was evaluated by stratified random sampling and statistical analysis of satellite classification (SCR) versus air photo interpretation results (PIR) for the overall classification and individual...

The use of the Cormack- Jolly-Seber model under a standard sampling scheme of one sample per time period, when the Jolly-Seber assumption that all emigration is permanent does not hold, leads to the confounding of temporary emigration probabilities with capture probabilities. This biases the estimates of capture probability when temporary emigration is a completely random process, and...

The patterns of selection by wolves (Canis lupus) preying on moose (Alces alces), caribou (Rangifer tarandus), and Dall sheep (Ovis dalli) in Denali National Park and Preserve, Alaska were studied from 1986 through early 1992. Wolves and their prey are legally protected or relatively unharvested in most of the area, and wolf numbers doubled during the study. Based on remains of 294 moose...

To examine sample size requirements and optimum allocation of effort in point count sampling of bottomland hardwood forests, we computed minimum sample sizes from variation recorded during 82 point counts (May 7-May 16, 1992) from three localities containing three habitat types across three regions of the Mississippi Alluvial Valley (MAV). Also, we estimated the effect of increasing the...

No abstract available at this time

High-TiO2, quartz-normative (HTQ) tholeiite sheets of Early Jurassic age have intruded mainly Late Triassic sedimentary rocks in several early Mesozoic basins in the eastern US. Field observations, petrographic study, geochemical analyses and stable isotope data from three HTQ sheet systems were used to develop a general model of magmatic differentiation and magmatic-hydrothermal...

This fraction, which is enriched in heavy minerals relative to the sand fraction, is mainly detrital but contains a strong authigenic component. The authigenic silt heavy-mineral fraction is largely a product of the lateritic weathering and dominated by iron oxides and alterites. Grains of bladed rutile and leached ilmenite are common. Spatial variability in silt-fraction mineralogy is

The Fischer and Porter Company Superfund Site is underlain by sedimentary rocks of the Upper Triassic Stockton Formation, which consists of interbedded siltstone, very-fine grained to coarse-grained sandstone, and conglomerate in crudely defined, upward fining cycles. These rocks form a complex, heterogeneous, leaky, multiaquifer system comprised of a series of gently dipping lithologic...

An analysis of historical pesticide data (1972-92) for the White River was conducted as part of the U.S. Geological Survey National Water-Quality Assessment Program. Data on the presence of pesticides in streams, bottom sediments, fish, and ground waters were examined. Results are interpreted with respect to spatial, seasonal, and streamflow effects. Concentrations of water-soluble...

Streambed-scour was assessed at 1,338 federal-aid bridges in southwestern Indiana during 1991. The assessments were conducted as part of a 7-year study by the U.S. Geological Survey in cooperation with the Indiana Department of Transportation (INDOT) that will evaluate 5,600 bridge sites throughout the State. Measurements and observations of remnant scour made during low-flow discharges...