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Research about Louisiana

Source-linked reports with geographic coverage including Louisiana.

At least 739 records · Page 41Linked to original sources
USGS1993

Body composition of wintering canvasbacks in Louisiana: Dominance and survival implications

I studied effects of sex, age, and month on body mass and composition of Canvasbacks ( Aythya valisineria ) at Catahoula Lake (CL) and the Mississippi River Delta (MRD), Louisiana, in winter 1987-1988. Size-adjusted body mass and fat varied by age, month, and site. Fat levels in immatures were greater at MRD than at CL, but changed similarly at both sites. Adults at MRD were also fatter than those at CL in early winter, especially in December, but fat levels of all birds increased from early to late winter and were equivalent by late winter. Body protein adjusted for structural size varied by age, month, and site, and sex, month, and site. Protein levels by site were higher in adults and males than in immatures and females, but sex- and age-related differences averaged <11 g (5%). Changes in size-adjusted leg muscle protein (index of feeding activity) and body fat were positively associated. This relation (my measure of feeding efficiency) was not affected by sex or age of Canvasbacks, implying that all birds at CL or MRD fed at similar efficiencies by month. At both sites, females were fatter than males; thus, although males were larger and potentially dominant to females, it appears that females were not disadvantaged in their acquisition of nutrients during the year of study. Body mass of CL and MRD birds in winter 1987-1988 was greater than that of Canvasbacks wintering elsewhere. If overwinter and annual survival of Canvasbacks are related to their relative body mass during winter, then survival probabilities of CL and MRD birds may be high compared to other wintering populations.

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USGS1993

Sex ratios of canvasbacks wintering in Louisiana

Disparate sex ratios in waterfowl are considered indicative of differential survival between the sexes and may limit reproductive potential. Because other studies have shown canvasbacks (Aythya valisineria) have highly skewed sex ratios, I examined aerial photographs from surveys flown monthly during winters 1987-88 and 1988-89 to determine sex ratios of canvasbacks in Louisiana where the wintering population is increasing. Estimated statewide sex ratios (proportion male) were balanced during the initial arrival period in November (1987: 0.505, 1988: 0.524), dominated by males during December-February (range = 0.600- 0.655), and then dominated by females as birds departed in March (1989: 0.419). Sex ratios varied geograph- ically with males being more prevalent in flocks at inland sites than in coastal areas. Canvasback sex ratios did not vary by flock size nor between major- and minor-use areas. Canvasback sex ratios in Louisiana appeared to be representative of the population wintering in the lower Mississippi Valley and Gulf Coast region and were less male dominated than the sex ratios projected for the population wintering in the Atlantic Flyway. Overall sex ratio characteristics imply that female canvasbacks in Louisiana may have higher annual survival or recruitment rates relative to males than occur in other wintering populations. I suggest that this may partially explain the observed increases in canvasbacks wintering in Louisiana.

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USGS1993

Survival of female canvasbacks wintering in coastal Louisiana

Annual survival probabilities of female canvasbacks ( Aythya valisineria ) are lower than those of males, but sources and timing of mortality are poorly understood. To further elucidate causes of reduced annual survival in female canvasbacks, we estimated survival rates for radio-tagged females in coastal Louisiana during winters 1988-91. Survival estimates for winters 1988-91 were 0.946 ± 0.072 (estimate ± 95% CI) for adults ( n = 82) and 0.952 ± 0.065 for immatures ( n = 51). High survival by females wintering in coastal Louisiana suggests that sex- and age-related differences in canvasback survival occur during other periods of the annual cycle or at other wintering or staging sites.

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USGS1993

Diet differences in Redheads from nearshore and offshore zones in Louisiana

Habitat management decisions for diving ducks in winter are limited by the lack of information concerning their use of nearshore and offshore zones. Therefore, we compared diets of redheads ( Aythya americana ) collected from nearshore (n = 206) and offshore (n = 72) zones during winters at the Chandeleur Islands, Louisiana, 1987-89. A greater (P < 0.05) proportion of redheads from nearshore had food in their esophagus and proventriculus than redheads from offshore. Feeding redheads in the offshore zone consumed more (P < 0.05) animal matter (42% in esophagus) and less plant material (58%) than conspecifics feeding nearshore (13% animal, 87% plant). Contents of proventriculi showed the same trend (P < 0.05). Zone-related diet differences occurred in both sexes and in early and late winter. Food availability and nutritional needs may affect these differences.

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USGS1993

Water resources data, Louisiana, water year 1992

Water resources data for the 1992 water year for Louisiana consists of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs: and water levels and water quality of ground water. This report contains records for water discharge at 60 gaging stations; stage only for 12 gaging stations and 6 lakes; water quality for 56 surface-water stations (including 12 gaging stations) and 121 wells; and water levels for 218 observation wells. Also included are data for 111 crest-stage and flood-profile partial-record stations. Additional water data were collected at various sites not involved in the systematic data-collection program, and are published as miscellaneous measurements. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in Louisiana.

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USGS1993

Production and decomposition of Spartina patens in a degrading coastal marsh

Production and decomposition rates were calculated for Spartina patens in a mesohaline coastal marsh in Louisiana. Production was estimated to be 800 g m 2 yr -1 during 1991 and 1,696 g m -1 yr -1 during 1992. The relative decomposition rate of S. patens stems was -0.001152 g g -1 d -1 which may be restated as a half life of 395 days. Both production and decomposition rates for this area are low relative to most other studies in coastal areas. These data contribute to our understanding of the dynamics of organic matter in degrading coastal wetlands.

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USGS1993

Time-activity budget of Northern Pintails using nonhunted rice fields in southwest Louisiana (Presupuesto de actividades cotidianas por parte de individuos de anas acuta en campos de arroz no utilizados para cazar en el suroeste de Louisiana)

Monthly behavioral observations of Northern Pintails ( Anas acuta ) were conducted on five leased tracts of nonhunted private land, each including 60 ha of flooded rice fields, in southwest Louisiana during November-February 1988-1989. Pintails spent 52% of diurnal time resting, 21% feeding, 16% in comfort activities, 6% in locomotion, 4% courting and 1% in other behaviors. Activities differed among months and periods of the day. Pintails used nonhunted rice fields only during the day, departing after sunset. Pintail time budgets in Louisiana approximated those reported in California. Pintails using rice fields during the day, however, fed more than did those roosting on open water pools at Lacassine National Wildlife Refuge (NWR), Louisiana. Small (60 ha), nonhunted rice fields provided wintering Northern Pintails security plus food during the day. Desde noviembre a febrero de 1988-1989 hicimos observaciones mensuales de la conducta de individuos de Anas acuta en cinco localidades privadas y libres de cacería, del suroeste de Lousiana. Cada área incluyó un campo de arroz inundado de 60 hectáreas. Los patos emplearon el 52% del tiempo diurno para descansar, 21% para alimentarse, 16% para actividades de confort, 6% para locomoción, 4% para cortejo y 1% para otras actividades. Hubo diferencias en las actividades a través de los meses de estudio y períodos del día. Los patos utilizaron las áreas libres de cacería durante el período diurno y partieron de las mismas con la puesta del sol. El presupuesto de tiempo de las aves de Louisiana se aproximó a los informados en California para la especie. Sin embargo, los patos que utilizaron los campos de arroz se alimentaron más que los que descansaron en pozas del Refugio Nacional de Vida Silvestre de Lacassine. Los pequeños campos de arroz, libres de cacería, proveyeron a los patos invernales de lugares seguros y de alimentación durante el período diurno.

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USGS1993

Marsh submergence vs. marsh accretion: Interpreting accretion deficit data in coastal Louisiana

The apparent imbalance between relative sea-level rise and vertical marsh accretion is frequently cited as a major factor in the problem of wetland loss in Louisiana. Rates of relative sea-level rise are high in Louisiana due to high rates of subsidence. Although marsh accretion rates are also high, they are usually insufficient to maintain the relative elevation of the marsh surface. This situation is commonly referred to as an accretion deficit. The interpretation of subsidence and accretion data, and therefrom accretion deficit data, is confounded by the numerous geologic, biologic, and sedimentologic processes influencing coastal marshes in Louisiana. Therefore, calculation of accretion deficits can be influenced by the techniques used to measure subsidence and accretion. The concept of accretion deficit is based on the assumption that accretion rates are equivalent to elevation change rates, but this assumption may not necessarily be correct. We suggest that direct measurements of elevation change in marsh surface can provide better indications of the status of the marsh surface with respect to subsidence and accretion.

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USGS1993

Spectral reflectance and canopy structure characteristics of gulf coast wetland vegetation types

Field measurements of canopy structure and species composition are related to spectral reflectance measurements taken with a radiometer over a number of marsh sites. Marsh vegetation types are discussed in terms of their characteristic canopy structure and phenology; the influence of these characteristics on spectral reflectance will be examined. Vegetation types that are discussed include Panicum hemitomon (fresh marsh) Spartina patens (brackish marsh), Spartina alterniflora and Juncus roemerianus (saline marsh). This work is part of the high resolution component of a study to develop methods to spectrally discriminate and monitor the wetlands of the gulf coast.

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USGS1992

Water resources data, Louisiana, water year 1991

Water resources data for the 1991 water year for Louisiana consist of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; and water levels and water quality of ground water. This report contains records for water discharge at 61 gaging stations; stage only for 12 gaging stations and 6 lakes; water quality for 43 surface-water stations (including 12 gaging stations), and 60 wells; and water levels for 206 observation wells. Also included are data for 116 crest-stage and flood-profile partial-record stations. Additional water data were collected at various sites not involved in the systematic data-collection program, and are published as miscellaneous measurements. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in Louisiana

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