Skip to main content
U.S. flag

An official website of the United States government

Publications

Explore WARC's science publications.

Filter Total Items: 3509

Survival of female canvasbacks wintering in coastal Louisiana 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 ±...
Authors
William L. Hohman, Ronald D. Pritchert, Joseph Moore, D.O. Schaeffer

Recent growth increases in old-growth longleaf pine Recent growth increases in old-growth longleaf pine

Longleaf pine (Pinuspalustris Mill.) tree-ring data were obtained from an old-growth stand located in Thomas County, Georgia. The tree-ring chronology from the pine stand is composed of a collection of cores extracted from 26 trees ranging in age from approximately 100 to 400 years. These cores were prepared, dated, and measured, and the resulting data were examined with...
Authors
D.C. West, T.W. Doyle, M.L. Tharp, J.J. Beauchamp, William J. Platt, D.J. Downing

Laguna madre: Seagrass changes continue decades after salinity reduction Laguna madre: Seagrass changes continue decades after salinity reduction

Vegetation maps of the lower Laguna Madre prepared from surveys conducted in 1965–1967, 1974–1976, and 1988 document a >330 km2 decrease in cover byHalodule wrightii, an increase of almost 190 km2 in other seagrass species, and an increase of 140 km2 in bare bottom. Loss in seagrass cover is confined to deeper parts of the laguna; turbidity caused by maintenance dredging is the suspected...
Authors
Millicent L. Quammen, Christopher P. Onuf

Body composition of wintering canvasbacks in Louisiana: Dominance and survival implications 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...
Authors
William L. Hohman

Relative effects of nutrient enrichment and grazing on epiphyte-macrophyte (Zostera marina L.) dynamics Relative effects of nutrient enrichment and grazing on epiphyte-macrophyte (Zostera marina L.) dynamics

The independent and interactive effects of nutrient concentration and epiphyte grazers on epiphyte biomass and macrophyte growth and production were examined in Zostera marina L. (eelgrass) microcosms. Experiments were conducted during early summer, late summer, fall, and spring in a greenhouse on the York River estuary of Chesapeake Bay. Nutrient treatments consisted of ambient or...
Authors
Hilary A. Neckles, R. L. Wetzel, R.J. Orth

Sex ratios of canvasbacks wintering in Louisiana 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...
Authors
Dennis W. Woolington
Was this page helpful?