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Water resources of Richland Parish, Louisiana

Information concerning the availability, use, and quality of water in Richland Parish, Louisiana, is critical for proper water-supply management. The purpose of this fact sheet is to present information that can be used by water managers, parish residents, and others for stewardship of this vital resource. In 2014, about 41.73 million gallons per day (Mgal/d) of water were withdrawn in Richland Parish, including about 28.57 Mgal/d from groundwater sources and 13.17 Mgal/d from surface-water sources. Withdrawals for agricultural use, composed of general irrigation, rice irrigation, aquaculture, and livestock uses, accounted for about 88 percent (36.88 Mgal/d) of the total water withdrawn. Other categories of use included public supply, which accounted for about 10 percent (4.38 Mgal/d) of the total water withdrawn and rural domestic which accounted for about 1 percent (0.48 Mgal/d). Water-use data collected at 5-year intervals from 1960 to 2010 and again in 2014 indicate that water withdrawals peaked in 1980 at more than 60 Mgal/d.

Louisiana

Water resources of Avoyelles Parish, Louisiana

Information concerning the availability, use, and quality of water in Avoyelles Parish, Louisiana, is critical for proper water-supply management. The purpose of this fact sheet is to present information that can be used by water managers, parish residents, and others for stewardship of this vital resource. In 2014, about 70 million gallons per day (Mgal/d) of water were withdrawn in Avoyelles Parish, including about 59.27 Mgal/d from groundwater sources and 10.95 Mgal/d from surface-water sources. Withdrawals for agricultural use—composed of aquaculture, general irrigation, livestock, and rice irrigation—accounted for 93 percent (65.59 Mgal/d) of the total water withdrawn. Other categories of use included public supply and rural domestic. Water-use data collected at 5-year intervals from 1960 to 2010 and again in 2014 indicated that water withdrawals peaked in 2014.

Louisiana

Water resources of Evangeline Parish, Louisiana

Information concerning the availability, use, and quality of water in Evangeline Parish, Louisiana, is critical for proper water-supply management. The purpose of this fact sheet is to present information that can be used by water managers, parish residents, and others for stewardship of this vital resource. In 2014, about 282.66 million gallons per day (Mgal/d) of water were withdrawn in Evangeline Parish, including about 122.05 Mgal/d from groundwater sources and 160.61 Mgal/d from surface-water sources. Withdrawals for agricultural use, composed of aquaculture, general irrigation, livestock, and rice irrigation, accounted for 45 percent (126.86 Mgal/d) of the total water withdrawn. Withdrawals for power-generation use accounted for about 52 percent (146.33 Mgal/d) of the total water withdrawn. Other categories of use included public supply, industry, and rural domestic. Water-use data collected at 5-year intervals from 1960 to 2010 and again in 2014 indicated that water withdrawals peaked in 1980.

Louisiana

Water resources of Red River Parish, Louisiana

Information concerning the availability, use, and quality of water in Red River Parish, Louisiana, is critical for proper water-supply management. The purpose of this fact sheet is to present information that can be used by water managers, parish residents, and others for stewardship of this vital resource. In 2014, about 5.76 million gallons per day (Mgal/d) of water were withdrawn in Red River Parish: about 4.23 Mgal/d from groundwater sources and 1.54 Mgal/d from surface-water sources. Withdrawals for agricultural use, composed of general irrigation, rice irrigation, and livestock uses, accounted for about 72 percent (4.15 Mgal/d) of the total water withdrawn. Other categories of use included public supply (about 18 percent of the total water withdrawn, or 1.03 Mgal/d), industry (about 7 percent, or 0.39 Mgal/d), and rural domestic (about 4 percent, or 0.20 Mgal/d). Water-use data collected at 5-year intervals from 1960 to 2010 and again in 2014 indicated that water withdrawals peaked in 1975 at more than 7.3 Mgal/d.

Louisiana

Water resources of St. Landry Parish, Louisiana

Information concerning the availability, use, and quality of water in St. Landry Parish, Louisiana, is critical for proper water-supply management. The purpose of this fact sheet is to present information that can be used by water managers, parish residents, and others for stewardship of this vital resource. In 2014, about 116.75 million gallons per day (Mgal/d) of water were withdrawn in St. Landry Parish: about 98.13 Mgal/d from groundwater sources and 18.62 Mgal/d from surface-water sources. Withdrawals for agricultural use, composed of general irrigation, rice irrigation, aquaculture, and livestock uses, accounted for about 90 percent (105.31 Mgal/d) of the total water withdrawn. Other categories of use included public supply, which accounted for about 8 percent of the total water withdrawn (9.77 Mgal/d), industry which accounted for about 1 percent (1.03 Mgal/d), and rural domestic which accounted for about 1 percent (0.65 Mgal/d). Water-use data collected at 5-year intervals from 1960 to 2010 and again in 2014 indicated that water withdrawals peaked in 1965 at 194.57 Mgal/d due to a large reported surface-water withdrawal of 144.00 Mgal/d for power generation that was not reported for other years.

Louisiana

Water resources of St. Martin Parish, Louisiana

Information concerning the availability, use, and quality of water in St. Martin Parish, Louisiana, is critical for proper water-supply management. The purpose of this fact sheet is to present information that can be used by water managers, parish residents, and others for stewardship of this vital resource. In 2014, about 46.99 million gallons per day (Mgal/d) of water were withdrawn in St. Martin Parish, including about 35.91 Mgal/d from groundwater sources and 11.08 Mgal/d from surface-water sources. Withdrawals for agricultural use, composed of aquaculture (32.28 Mgal/d), rice irrigation (6.44 Mgal/d), general irrigation (2.38 Mgal/d), and livestock uses (0.06 Mgal/d), accounted for about 88 percent (41.16 Mgal/d) of the total water withdrawn. Other categories of use included public supply, which accounted for about 10 percent (4.83 Mgal/d), rural domestic, which accounted for about 2 percent (0.81 Mgal/d), and industry, which accounted for less than 1 percent (0.18 Mgal/d). Water-use data collected at 5-year intervals from 1960 to 2010 and again in 2014 indicate that water withdrawals in St. Martin Parish peaked in 1985 at more than 68 Mgal/d.

Louisiana

Delineation of marsh types and marsh-type change in coastal Louisiana for 2007 and 2013

The Bureau of Ocean Energy Management researchers often require detailed information regarding emergent marsh vegetation types (such as fresh, intermediate, brackish, and saline) for modeling habitat capacities and mitigation. In response, the U.S. Geological Survey in cooperation with the Bureau of Ocean Energy Management produced a detailed change classification of emergent marsh vegetation types in coastal Louisiana from 2007 and 2013. This study incorporates two existing vegetation surveys and independent variables such as Landsat Thematic Mapper multispectral satellite imagery, high-resolution airborne imagery from 2007 and 2013, bare-earth digital elevation models based on airborne light detection and ranging, alternative contemporary land-cover classifications, and other spatially explicit variables. An image classification based on image objects was created from 2007 and 2013 National Agriculture Imagery Program color-infrared aerial photography. The final products consisted of two 10-meter raster datasets. Each image object from the 2007 and 2013 spatial datasets was assigned a vegetation classification by using a simple majority filter. In addition to those spatial datasets, we also conducted a change analysis between the datasets to produce a 10-meter change raster product. This analysis identified how much change has taken place and where change has occurred. The spatial data products show dynamic areas where marsh loss is occurring or where marsh type is changing. This information can be used to assist and advance conservation efforts for priority natural resources.

Louisiana

The ecological condition of estuaries in the Gulf of Mexico

The Gulf of Mexico is a vast natural resource encompassing the coastal areas of western Florida, Alabama, Mississippi, Louisiana, and Texas, as well as a portion of Mexico. Many estuaries flow into the Gulf of Mexico and serve as nursery grounds for fish, habitat for a wide variety of wildlife, shipping routes, and a source of recreation. Estuarine-dependent species constitute more than 95 percent of the commercial fishery harvests from the Gulf of Mexico, and many important recreational fishery species depend on estuaries during some part of their life cycle. Gulf estuaries are diverse and productive ecosystems that provide a variety of valuable resources, including fish and shellfish, recreation, transportation, and water supply. Assessing the overall condition of Gulf of Mexico estuaries required incorporating data from other federal, state, and local monitoring programs to augment the information on ecological indicators collected by the U.S. Environmental Protection Agency’s (USEPA) Environmental Monitoring and Assessment Program (EMAP). The resulting document would provide a synthesis of the available knowledge about the condition of Gulf of Mexico estuaries. This document is intended for use by scientists and other citizens concerned with the ecological condition of estuaries, as well as by managers and lawmakers interested in the sustained use of estuaries for commercial and recreational purposes. It also addresses public concerns about the aesthetic quality of coastal areas vital to tourism and recreation. By producing this report on the ecological condition of estuaries in the Gulf of Mexico, we have taken one step in assessing the health of this environmental resource. We have produced an environmental “report card” to be used as a guide in the evaluation of management decisions and research directions. This report is organized in three parts: (1) an introduction that gives background information on the Gulf of Mexico, estuarine ecology, and the factors that impact estuaries in the gulf, (2) the main section on priority ecological indicators used to measure the condition of estuaries in the gulf and (3) an ecological report card that summarizes the data on ecological indicators and provides a rating of the condition of estuaries in each gulf state and for gulf estuaries overall. Many of the ratings were based on the percent area of estuaries in each state exhibiting degraded or adverse levels of an indicator. Eutrophication, a condition of high nutrients often resulting in low oxygen levels and other adverse effects, is an important water quality concern for estuaries along the gulf coast. The National Oceanic and Atmospheric Administration (NOAA) has compared the Gulf of Mexico to other coastal regions like the middle Atlantic and has ranked the Gulf of Mexico as having the highest number of point sources of nutrients and the highest percentage of land use devoted to agriculture. We evaluated monitoring data for nitrogen, chlorophyll, and dissolved oxygen as indicators of eutrophication. Although most of the estuaries exhibited high nitrogen or chlorophyll or low dissolved oxygen concentrations at least once during a survey, many times these conditions were observed in small rivers or bayous rather than in the entire estuary. Often, the percent area affected was low. The gulf estuaries had moderate conditions overall for nutrients and dissolved oxygen. Definite nutrient problems were observed in >25% of the estuarine area in Louisiana and Texas and definite dissolved oxygen problems were observed in Alabama. Contaminants in estuarine sediments provide evidence of the accumulation of chemicals from anthropogenic sources. We compared the concentrations of sediment contaminants to established guideline values to determine the proportion of estuarine area that could have potential adverse effects on living organisms. Although detectable levels of contaminants were measured in almost every estuary in the Gulf of Mexico, <25% of the estuarine area in all states had contaminant concentrations that exceeded these guidelines. Wetlands are integral parts of estuarine systems. Declining acreage means habitat loss that may be the result of commercial and residential development, hydrologic alterations, or dredge and fill operations. The Gulf of Mexico region contains more than 50% of the coastal wetland acreage in the U.S. and yet it also has the highest rate of coastal wetland loss. Nine of the top ten estuarine drainage areas ranked by total wetland area are in the Gulf of Mexico region. The most current estimates of total wetland loss over the past 200 years range from 41% to 54% for the gulf states. Although coastal wetlands continue to be altered or destroyed, some estimates indicate that the rate of loss has slowed. All gulf states were rated as having severe problems with wetland loss. The condition of benthic (bottom-dwelling) invertebrates, fish and shellfish, birds, and threatened and endangered species was used to evaluate the health of estuarine fauna. Degraded benthic communities inhabited <25% of the estuarine area in all gulf states except for Texas. Commercial fish and shellfish landings may be used as an indicator of population stability while fish biomarkers are used to measure the health of individuals in the population. Commercial landings of the top four fisheries (shrimp, menhaden, blue crab, and oyster) are stable in the gulf states while fish biomarkers indicate fair to poor fish health in Alabama and Texas and good fish health elsewhere. Coastal and marine bird populations appear to be in good condition throughout the gulf. Four threatened or endangered species inhabit coastal areas in the Gulf of Mexico: brown pelican, Gulf sturgeon, manatee, and Kemp’s ridley sea turtle. In general, populations of these species are in good to fair condition in the gulf states. Public health indicators include shellfish bed closures and chemicals found in edible fish tissue. Harvest of shellfish (primarily oyster in the Gulf of Mexico) is restricted or prohibited when concentrations of bacteria or other pathogens reach levels that could impair human health. The gulf states contain the most acreage of shellfish-growing waters in the U.S. but also have the most acreage restricted for harvest. All gulf states except Mississippi have >25% of their shellfish-growing waters restricted for harvest, mostly due to pollution from wastewater treatment plants or other upstream sources. Advisories may be issued that limit consumption when the concentrations of chemicals in fish tissue exceed levels known to be harmful to humans. Although seafood consumption advisories have been issued in all gulf states, the percent of the fish population with high concentrations of contaminants is relatively low in the gulf overall.

Alabama, Florida, Louisiana, Mississippi, Texas

Spatial models of Northern Bobwhite populations for conservation planning

Since 1980, northern bobwhite (Colinus virginianus) range-wide populations declined 3.9% annually. Within the West Gulf Coastal Plain Bird Conservation Region in the south-central United States, populations of this quail species have declined 6.8% annually. These declines sparked calls for land use change and prompted implementation of various conservation practices. However, to effectively reverse these declines and restore northern bobwhite to their former population levels, habitat conservation and management efforts must target establishment and maintenance of sustainable populations. To provide guidance for conservation and restoration of habitat capable of supporting sustainable northern bobwhite populations in the West Gulf Coastal Plain, we modeled their spatial distribution using landscape characteristics derived from 1992 National Land Cover Data and bird detections, from 1990 to 1994, along 10-stop Breeding Bird Survey route segments. Four landscape metrics influenced detections of northern bobwhite: detections were greater in areas with more grassland and increased aggregation of agricultural lands, but detections were reduced in areas with increased density of land cover edge and grassland edge. Using these landscape metrics, we projected the abundance and spatial distribution of northern bobwhite populations across the entire West Gulf Coastal Plain. Predicted populations closely approximated abundance estimates from a different cadre of concurrently collected data but model predictions did not accurately reflect bobwhite detections along species-specific call-count routes in Arkansas and Louisiana. Using similar methods, we also projected northern bobwhite population distribution circa 1980 based on Land Use Land Cover data and bird survey data from 1976 to 1984. We compared our 1980 spatial projections with our spatial estimate of 1992 populations to identify areas of population change. Additionally, we used our projection of the spatial distribution and abundance of bobwhite to predict areas of population sustainability. Our projections of population change and sustainability provide guidance for targeting habitat conservation and rehabilitation efforts for restoration of northern bobwhite populations in the West Gulf Coastal Plain.

Journal of Wildlife Management

A new tool to assess groundwater resources in the Mississippi embayment

What is the Mississippi Embayment? The Mississippi embayment study area encompasses approximately 78,000 square miles in eight States and includes large parts of Arkansas, Louisiana, Mississippi, and Tennessee, and smaller areas of Alabama, Illinois, Kentucky, and Missouri (fig. 1). The Mississippi embayment is essentially a basin that slopes toward the Gulf of Mexico and is filled with sediments of alternating sand, silt, and clay layers. There are two principal aquifers in the embayment-the Mississippi River Valley alluvial aquifer (alluvial aquifer) and the middle Claiborne aquifer (fig. 1). The shallow alluvial aquifer is the primary source of groundwater for irrigation in the largely agricultural region, while the deeper middle Claiborne aquifer is a primary source of drinking water for many of the 5.2 million people living in the embayment. The U.S. Geological Survey (USGS) is conducting large-scale multidisciplinary regional studies of groundwater availability for the Nation. Studies comprise individual assessments of regional groundwater-flow systems that encompass varied terrains and document a comprehensive regional and national perspective of groundwater resources. Collectively, these studies are the foundation for the national assessment of groundwater availability and are conducted in cooperation with other Federal, State, local governments, and the private sector. Numerical groundwater-flow models are used in these studies to document effects of human activities and climate variability on groundwater levels, changes in aquifer storage, and flow between groundwater and surface-water bodies. As part of the Mississippi Embayment Regional Aquifer Study (MERAS), a numerical model was constructed of 13 layers over 78,000 square miles representing multiple aquifers and confining units for the period of 1870 to 2007. The model is a tool that was used to assess and better understand groundwater resources.

Mississippi

Environmental setting, water quality, and ecological indicators of surface-water quality in the Mermentau River Basin, southwestern Louisiana, 1998-2001

The U.S. Geological Survey collected data from 29 wells and 24 surface-water sites in the Mermentau River Basin, 1998-2001, to better understand ground-water and surface-water quality; aquatic invertebrate communities; and habitat conditions, in relation to land use. This study was apart of the National Water-Quality Assessment Program, which was designed to assess water quality as it relates to various land uses. Water-quality data were evaluated with criteria established for the protection of drinking water and aquatic life, and bed-sediment data were compared to aquatic life criteria. Water-quality and ecological data were analyzed statistically in relation to drainage area and agricultural land-use integrity. Concentrations of nutrients and major inorganic ions in ground water and surface water generally were highest in the southeastern part of the study area where soils contain thick loess deposits. Peak concentrations of nutrients in surface water occurred March-may at two sites with high agricultural intensity; the lowest concentrations occurred August-January. The greatest potential for eutrophic conditions in surface water, based on nutrient concentrations, existed March-May, at about the same time or shortly after ricefields were drained. Secondary Maximum Contaminant Levels established by the U.S. Environmental Protection Agency (USEPA) were exceeded for sulfate, chloride, iron, or manganese in samples from 20 wells, and for iron or manganese in samples from all surface-water sites. Fewer pesticides were detected in ground water than in surface water. In 11 of of the 29 wells sampled, at least one pesticide or pesticide degradation product was detected. The most frequently detected pesticides or pesticide degradation products in ground water were the herbicides benzaton and atrazine. Concentrations of 47 pesticides and degradation products were detected in surface water. At least 3 pesticides were detected in all surface-water samples. In 72 percent of the samples at least 5 hydrophilic pesticides were detected, and in more than 70 percent of the samples at least 3 hydrophobic pesticides were detected. Although atrazine concentrations in three samples collected in the spring exceeded 3 micrograms per liter, the USEPA Maximum Contaminant Level of 3 micrograms per liter was not exceeded because it is based on an annual average of quarterly samples. Concentrations larger than 3.0 micrograms per liter were not detected in samples collected during other times of the year. Tebuthiuron was detected at all surface-water sites; the largest concentration (6.33 micrograms per liter) was detected at a site on Bayou des Cannes, and was the only detection that exceeded the criterion (1.6 micrograms per liter) for the protection of aquatic life. Malathion was detected at 16 surface-water sites; the largest concentration (0.113 micrograms per liter) was detected at a site on Bayou Lacassine and was the only detection that exceeded the criterion (0.1 micrograms per liter) for the protection of aquatic life. Concentrations of fipronil exceeded numeric targets for acute total maximum daily loads (2.3 micrograms per liter) at 3 sites and chronic total maximum daily loads (4.6 micrograms per liter) at 14 sites. Maximum pesticide concentrations in surface water usually occurred in the spring at about the same time or shortly after ricefields were drained. Concentrations of DDE in bed sediment at two sites exceeded interim freshwater sediment quality guidelines for the protection of aquatic life. Fipronil sulfide and desulfinylpronil were detected at all 17 sites from which bed-sediment samples were collected, but there are no current (2002) guidelines with which to evaluate the environmental effects of fipronil and degradation products. Two methods were used to group the ecological data-collection sites: (1) Sites were grouped before data collection (according to the study design) using drainage area

Water-Resources Investigations Report

Results of a workshop concerning ecological zonation in bottomland hardwoods

Under Section 404 of the Clean Water Act, the U.S. Environmental Protection Agency (EPA) has regulatory responsibilities concerning the discharge of dredged or fill material into the Nation's waters. In addition to its advisory role in the U.S. Army Corps of Engineers' permit program, EPA has a number of specific authorities, including formulation of the Section 404(b)(1) Guidelines, use of Section 404(c) to prohibit disposal at particular sites, and enforcement actions for unauthorized discharges. A number of recent court cases focus on the geographic scope of Section 404 jurisdiction in potential bottomland hardwood (BLH) wetlands and the nature of landclearing activities in these areas that require a permit under Section 404. Accordingly, EPA needs to establish the scientific basis for implementing its responsibilities under Section 404 in bottomland hardwoods. EPA is approaching this task through a series of workshops designed to provide current scientific information on bottomland hardwoods and to organize that information in a manner pertinent to key questions, including the following. What are the characteristics of bottomland hardwoods (in terms of hydrology, soils, vegetation, fish, wildlife, agricultural potential, and the like) and how can the functions (e.g., flood storage, water quality maintenance, detrital export) that they perform best be quantified? How do perturbations like landclearing, levee construction, and drainage impact the functions that bottomland hardwoods perform and how can these effects best be quantified? And finally, how significant are the impacts and how is their significance likely to change under various management scenarios? The first workshop in this series was held December 3-7, 1984, in St. Francisville, Louisiana. The workshop was attended by over 40 scientists and regulators (see ACKNOWLEDGMENTS section) and facilitated by the editors of this report under an Interagency Agreement between EPA and the U.S. Fish and Wildlife Service. The general objective of the workshop was to examine ways in which the structure and function of BLH ecosystems can be characterized and, in particular, to investigate the utility of a conceptual framework developed at a workshop held in Lake Lanier, Georgia, in 1980. In this framework, the transition from aquatic habitats to upland habitats through a BLH ecosystem is divided into six zones based on concomitant variation in the soil moisture regime and associated vegetation (Table 1). The zonation concept is of particular interest to EPA from at least two perspectives. The first is simply as a framework for organizing information. If the zones are discernible in the field, have recognizable characteristics, and perform identifiable functions, they might form a useful basis for tasks such as assessing the impacts of a particular site-specific activity. The second is the potential utility of the zonation concept in identifying the wetland portions of BLH communities. If the zones can be recognized in the field, and if one or more of them can be shown consistently to have wetland characteristics (i.e., perform functions, such as detrital export, often attributed to wetlands), while others do not, then the zones might have utility in identifying areas that fall under the jurisdiction of Section 404. The workshop itself was divided into two parts. The first was a series of papers in which authors described current research and data-synthesis activities in the context of the zonation concept. The second was a series of six workgroups in which participants discussed the zonation concept from the perspective of hydrology, soils, vegetation, fish, wildlife, and ecosystem processes. This report is a compilation of the written material from those workgroups, much of which was produced at the workshop. The formal papers presented in the first part of the workshop have been distributed to participants under separate cover, but are referenced in this report by citations such as: (Jones, workshop presentation).

Report

Water resources of Pointe Coupee Parish, Louisiana

Information concerning the availability, use, and quality of water in Pointe Coupee Parish, Louisiana, is critical for proper water-supply management. The purpose of this fact sheet is to present information that can be used by water managers, parish residents, and others for stewardship of this vital resource. In 2014, 364 million gallons per day (Mgal/d) of water were withdrawn in Pointe Coupee Parish, including about 39.87 Mgal/d from groundwater sources and 323.72 Mgal/d from surface-water sources. Withdrawals for power generation accounted for 89 percent (323.98 Mgal/d) of the total water withdrawn. Withdrawals for agricultural use, composed of aquaculture, general irrigation, livestock, and rice irrigation, accounted for 8 percent (29.29 Mgal/d) of the total water withdrawn. Other categories of use included public supply, industrial, and rural domestic. Water-use data collected at 5-year intervals from 1960 to 2010 and again in 2014 indicated that water withdrawals peaked in 2014. The large increase in surface-water withdrawals from 1980 to 1985 is attributable to an increase of 262 Mgal/d for power-generation use.

Louisiana

Water resources of Grant Parish, Louisiana

Information concerning the availability, use, and quality of water in Grant Parish, Louisiana, is critical for proper water-supply management. The purpose of this fact sheet is to present information that can be used by water managers, parish residents, and others for stewardship of this vital resource. In 2014, about 5.43 million gallons per day (Mgal/d) of water were withdrawn in Grant Parish, including about 2.39 Mgal/d from groundwater sources and 3.03 Mgal/d from surface-water sources. Withdrawals for public-supply use accounted for 71 percent (3.84 Mgal/d) of the total water withdrawn. Withdrawals for agricultural use, composed of general irrigation and livestock uses, accounted for 24 percent (1.28 Mgal/d) of the total water withdrawn. Other categories of use included industrial and rural domestic. Water-use data collected at 5-year intervals from 1960 to 2010 and again in 2014 indicated that water withdrawals peaked in 1960.

Louisiana

Feeding ecology of mallards wintering in Nebraska

Food use by mallards ( Anas platyrhynchos ) wintering on the Platte River in south central Nebraska was determined from mid-December to early March 1978-80. Mallards foraged in river channels, irrigation drainage canals, and agricultural areas. Plant matter formed 97% of the diet (dry weight) and diets did not vary between sexes (P > 0.05). Waste corn was the principal food consumed and formed 46 and 62% of the diets of males and females, respectively. Milo, common duckweed ( Lemna minor ), smartweed ( Polygonum spp.), and barnyardgrass ( Echinochloa muricata ) composed most of the remaining plant matter ingested. Mallards fed intensively in riparian wetland habitat to obtain invertebrates, but few were consumed because of limited abundance. Dietary protein was lower than reported among mallards wintering in Louisiana. Field feeding occurred primarily in grazed corn stubble and cattle feedlots. The distances traveled to feed, and the duration and timing of feeding varied with snow cover and season phenology. Competition for food was markedly higher during the cold winter of 1979 when heavy snow cover was present.

Nebraska

Quantifying hydrologic alteration in an area lacking current reference conditions—The Mississippi Alluvial Plain of the South-Central U.S.

To better understand the effects of hydrologic alteration as they relate to human and biological needs within the Mississippi Alluvial Plain of the south-central United States, the quantification of hydrologic alteration is required. Quantifying hydrologic alteration in the Mississippi Alluvial Plain is particularly difficult because of the lack of current reference, or even relatively undisturbed, U.S. Geological Survey (USGS) streamflow-gaging stations. Water withdrawals for agriculture in the form of weirs, dams, channelization and other forms of regulation within the Mississippi Alluvial Plain increased substantially beginning around 1960 suggesting that streamflow is substantially altered after this time period. To overcome the lack of stations that exist in the present that are unaffected by anthropogenic activities (or current reference stations), historical streamflow data were used to estimate what streamflow would be in the present without anthropogenic influence (or current reference conditions). These data, when combined with current streamflow information collected by the USGS in south and eastern Arkansas, southwest corner Kentucky, Louisiana, western Mississippi, southeastern corner Missouri, extreme western Tennessee, and extreme southeastern Texas were used to assess the level of hydrologic alteration within the study area.

Arkansas, Kentucky, Louisiana, Mississippi, Missou

Predictable interregional movements by female northern pintails during winter

Factors influencing initiation of regional and interregional movements by nonbreeding ducks are poorly understood, especially during winter. During winters 1990-1991 through 1992-1993, we radiotagged 347 female Northern Pintails (Anas acuta) in southwestern Louisiana and monitored their movements to three regions: (1) the Gulf Coast Region of Louisiana and Texas (outside of southwestern Louisiana), (2) the Rice Prairie Region of Texas, and (3) the Mississippi Alluvial Valley. We found that adult females were 1.9 times more likely than were immatures to emigrate from southwestern Louisiana during winter. During winters 1990-1991 and 1991-1992, females were more likely to emigrate during stormy than during fair weather, whereas they were more likely to emigrate during fair weather in 1992-1993. Females were more likely to emigrate during duck-hunting seasons than during nonhunting seasons, regardless of weather. Daily emigration probabilities did not differ in relation to body condition when released (body mass adjusted for body size) or to number of previous emigration events. Each winter, large numbers of females consistently moved from the Gulf Coast Region to areas with abundant rice (Oryza sativa) agriculture within the Mississippi Alluvial Valley. We conclude that destination of interregional movements by this population of Northern Pintails is highly predictable, and that initiation of such movements is influenced by female age and long-term winter precipitation patterns in the Mississippi Alluvial Valley. Furthermore, timing of these movements is predictable, based not on calendar date, but rather on duck-hunting seasons and, usually, the environmental cues to habitat availability provided by stormy weather.

Waterbirds

Occupancy and abundance of wintering birds in a dynamic agricultural landscape

Assessing wildlife management action requires monitoring populations, and abundance often is the parameter monitored. Recent methodological advances have enabled estimation of mean abundance within a habitat using presence–absence or count data obtained via repeated visits to a sample of sites. These methods assume populations are closed and intuitively assume habitats within sites change little during a field season. However, many habitats are highly variable over short periods. We developed a variation of existing occupancy and abundance models that allows for extreme spatio‐temporal differences in habitat, and resulting changes in wildlife abundance, among sites and among visits to a site within a field season. We conducted our study in sugarcane habitat within the Everglades Agricultural Area southeast of Lake Okeechobee in south Florida. We counted wintering birds, primarily passerines, within 245 sites usually 5 times at each site during December 2006–March 2007. We estimated occupancy and mean abundance of birds in 6 vegetation states during the sugarcane harvest and allowed these parameters to vary temporally or spatially within a vegetation state. Occupancy and mean abundance of the common yellowthroat ( Geothlypis trichas ) was affected by structure of sugarcane and uncultivated edge vegetation (occupancy = 1.00 [ = 0.96–1.00] and mean abundance = 7.9 [ = 3.2–19.5] in tall sugarcane with tall edge vegetation versus 0.20 [ = 0.04–0.71] and 0.22 [ = 0.04–1.2], respectively, in short sugarcane with short edge vegetation in one half of the study area). Occupancy and mean abundance of palm warblers ( Dendroica palmarum ) were constant (occupancy = 1.00, = 0.69–1.00; mean abundance = 18, = 1–270). Our model may enable wildlife managers to assess rigorously effects of future edge habitat management on avian distribution and abundance within agricultural landscapes during winter or the breeding season. The model may also help wildlife managers make similar management decisions involving other dynamic habitats such as wetlands, prairies, and even forested areas if forest management or fires occur during the field season.

Florida