Geology topics

Thomas C. Michot

Publications and source records attributed to Thomas C. Michot.

22 records · Page 2Linked to original sources

USGS1995

Survey for blood parasites in redheads (Aythya americana) wintering at the Chandeleur Islands, Louisiana

We detected no infections with species of Plasmodium , Haemoproteus , Leucocytozoon , Sarcocystis or Trypanosoma in blood smears, liver and spleen impressions, and muscle tissue from 136 redheads ( Aythya americana ) collected or captured at the Chandeleur Islands, Louisiana (USA), during three winters (1987 to 1990). One bird, a juvenile male, was infected with an unidentified species of microfilaria. Thus, we found no evidence that hematozoa had an effect on redheads during the course of the study.

Louisiana↗

USGS1994

Effects of weather and tides on feeding and flock positions of wintering redheads in the Chandeleur Sound, Louisiana

We studied the effects of weather and tides on percent feeding and flock positions of wintering redheads ( Aythya americana Eyton) in the Chandeleur Sound, Louisiana, USA. Flock scans ( n = 750) were made on 55 flocks from November through March of 1988–1989. The percent of the flock that was feeding was negatively correlated with time of day, temperature, water level, and distance of the flock from shore, and was positively correlated with wind velocity, flock size, fetch, and wave height; birds also fed more in early winter and during northerly winds. Flocks were closer to land earlier in the winter on cloudy, rainy, and windy days when waves were high, and those flocks were smaller than flocks farther from shore. Conditions associated with reduced fetch by flocks included later time of day, smaller waves, warmer air temperatures, northerly wind shifts, stronger winds, increasing cloud cover, and rain. Redheads minimized energy expenditure by foraging during low tides and in shallow water closer to shore; they increased feeding and reduced fetch during times of high thermoregulatory demands.

Louisiana↗

USGS1994

Winter biomass and nutrient values of three seagrass species as potential foods for redheads (Aythya americana eyton) in Chandeleur Sound, Louisiana

We studied biomass and macronutrient content of Halodule wrightii (shoalgrass) throughout the winter and of Thalassia testudinum (turtlegrass) and Syringodium filiforme (manateegrass) in January in Chandeleur Sound, Louisiana Halodule , the primary fcod of wintering redheads, had the lowest biomass of the three species on the study area in mid-winter. Macronutrient content of Halodule did not change during the winter, but aboveground and belowground biomass showed a 90 and 49% ( P <0.0001) decrease from October to March. Macronutrient content seems not to be the basis for selection by redheads of Halodule over the other two seagrass species or of selection of belowground over aboveground parts.

Louisiana↗

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.

Louisiana↗