Geology topics

Research about Catahoula Lake, Mississippi River Delta

Source-linked reports with geographic coverage including Catahoula Lake, Mississippi River Delta.

4 recordsLinked 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.

Louisiana↗

USGS1990

Food habits of wintering canvasbacks in Louisiana

We studied the food habits of canvasbacks ( Aythya valisineria ) at Catahoula Lake (inland) and the Mississippi River Delta (coastal), Louisiana, from November 1987 to February 1988. Plant foods comprised >97 aggregate percent dry mass of the canvasback diet. The proportion of plant material eaten did not vary with sex, age, or month, or differ between study sites or nocturnal and diurnal collections. Tubers of chufa flatsedge ( Cyperus esculentus ) and common arrowhead ( Sagittaria latifolia ) made up 94% of the canvasback diet at Catahoula Lake. Common and grassy arrowhead ( Sagittaria graminea ) tubers and American bulrush ( Scirpus americanus ) rhizomes and seeds formed 94% of the canvasback diet at the Mississippi River Delta. Consumption of specific food taxa did not vary with sex, age, or month at either study site. Canvasbacks at the Mississippi River Delta preferred seeds of American bulrush over all other foods, but American bulrush rhizomes were underrepresented in the diet. Densities of subterranean plant foods at Catahoula Lake and the Mississippi River Delta are apparently higher than at other major canvasback concentration areas and enable canvasbacks wintering in Louisiana to improve their physical condition before spring migration.

Louisiana↗

USGS1990

Influence of ingested lead on body mass of wintering canvasbacks

We determined the prevalence of lead shotgun pellets in gizzards of canvasbacks ( Aythya valisineria ) collected at Catahoula Lake and the Mississippi River Delta, Louisiana, during winter 1987-88 to assess the influence of ingested lead shot on canvasback body mass. The prevalence of ingested lead shot was significantly higher at Catahoula Lake (27%) than at the Mississippi River Delta (4%). Canvasbacks collected at Catahoula Lake showed significant differences in prevalence of ingested lead shot by age and month. We attributed age-related and seasonal variations to differences in foraging effort and exposure time. Body mass of canvasbacks at Catahoula Lake, after accounting for age, monthly variation, and body size, was significantly reduced (120 g or 10%) in birds that had lead shot in their gizzards.

Louisiana↗

USGS1990

Diurnal time-activity budgets of wintering canvasbacks in Louisiana

We determined diurnal time-activity budgets of Canvasbacks ( Aythya valisineria ) at Catahoula Lake and at the Mississippi River Delta, Louisiana, from December 1987 to March 1988. Canvasback feeding, resting, locomotory, and comfort activities varied by month and location with a month-location interaction. Moreover, the percentage of time spent feeding varied by sex with a month-sex interaction. Study site differences in the time- activity budgets of wintering Canvasbacks may be related to characteristics of their foods, foraging mode, disturbance level, and physical features of habitats at the two study sites. Canvasbacks wintering in Louisiana generally spent less time feeding and more time resting during the day than they did in Mississippi or coastal South Carolina. Levels of agonistic behavior were lower than those observed in South Carolina. We found no evidence of male dominance of female Canvasbacks in Louisiana.

Louisiana↗