Robert H. Chabreck

Diel movement of muskrats (Ondatra zibethicus) in a Louisiana brackish, coastal marsh was determined using 37 radio-collared muskrats and a total of 2,046 radio fixes during a 13-month period. Monthly home range averaged 0.48 ha but varied considerably among animals; no differences in home ranges were detected among seasons or sex-age classes of muskrats. Also, no differences in hourly movements were found among sex-age classes during periods of day. During winter and spring, differences were detected among individual muskrats. Comparison of seasonal means for all times of day and for all...

Digestive tracts were examined from 115 lesser scaup (Aythya affinis) killed by hunters in impoundments managed for crayfish (Procambarus clarkii) production at Indigo Island, Iberville Parish, Louisiana. Plant material (seeds) comprised 99.7% (by dry weight) of the food material during the 1981-82 wintering season and 99.6% during the 1982-83 season. Twenty-three scaup were collected while they were actively feeding; animal material was present in 21 scaup esophagi and plant material was present in 22. Nevertheless, plant material was the major food and comprised 99.0% of the diet. Seeds...

Data from a trapper survey in Louisiana for the 1980-81 season were used to estimate river otter (Lutra canadensis) harvest for each parish, and the data were compared in a step-wise regression procedure in 53 noncoastal parishes with independent variables thought to affect otter harvest. Of the factors tested, those most responsible for variation in the number of otters harvested were the amount of forested and nonforested wetlands, number of trapping licenses sold, and acreage of cotton in 1980. Otter occurrence was indexed in 6 parishes by otter latrine sites in transects along selected...

Field studies of delta duckpotatoes (Sagittaria graminae var. platyphylla) disclosed that plant density was 1.5 times greater in wildlife exclosures than in control areas. Tuber production where nutrias (Myocastor coypus) and ducks were excluded was 652.3 g/m2• Tuber production was considerably less in plots subjected to foraging by wildlife (nutria foraging only: 104.7 g/m2, duck foraging only: 75.8 g/m2 , nutria and duck foraging: 64.8 g/m2 ). Tubers were found to a soil depth of 30 em but where animals were excluded greatest production (40.3%) was at the 10-15 cm depth. Nutrias foraged...

Winter foods of the river otter (Lutra canadensis) in southern Louisiana were determined to gain an understanding of prey eaten by otters. Otters were taken by trappers in the salt marsh in southeastern Louisiana and freshwater swamp in the Atchafalaya Basin in southcentral Louisiana. Fishes were found in 83.3% of the digestive tracts from salt marsh and 83.0% of the tracts from the swamp area. Blue crabs (Callinectes sapidus) occurred in 19.8% of the digestive tracts from salt marsh and 3.8% of the tracts from the swamp area. Crayfishes (Procambarus sp.) were found in 34.% of the swamp...

Scirpus olneyi and Spanina patens were grown in mixed stands in containers (surlace area: 900 cm2) and burned during the fall and winter on 6 dates (Burn 1, 8 October; Burn 2, 23 October; Burn 3, 8 December; Burn 4, 20 December; Burn 5, 6 February; and Burn 6, 20 February). Plants in 18 separate containers were burned on leach date and 18 containers were left unburned as a control. Biweekly counts were made of the number of culms of each species per container from 5 October to 18 April. A positive linear relationship (P < 0.05) was noted between culm production of both species and...

Nutria (Myocastor coypus) were collected monthly from June 1976 to December 1978 and examined for sores resulting from the awns of smooth beggartick (Bidens laevis). Nutria became infected in December and were heavily infected from January to March. Eleocharis spp. were the taxa most commonly found in association with Bidens laevis.

The abundance of various species of wildlife in marshes and ponds influenced by weirs was measured and compared to similar data collected on non-wetTed or control areas from January through December, 1974. Weirs were constructed in marsh drainage systems and held water levels in ponds and bayous several inches below the elevation of the adjacent marsh; however, control areas were subjected to natural tidal influences. Greater duck, coot, and non-game bird usage was found in ponds influenced by weirs, especially during low water periods occurring in the winter. Field data indicated that...

Rooted vegetation in lakes of the Atchafalaya River Basin was adversely affected by increasing water turbidities from rising flood waters. Duck food plants decreased 80 percent from October 1972 to October 1973 as a result of severe flooding. Different sections of the basin were affected more than others by high water levels. Pest plants were a problem throughout most of the basin but presented no great problem in the study areas. Lakes in the lower section ofthe swamp region and the marsh region had the highest occurrence of vegetation during the study period. The middle and lower...

From January 1973 to September 1974, a study was conducted at Rockefeller Rehlge, Grand Chenier, Louisiana to determine the effects of irrigating Scirpus olneyi with various concentrations of salt water during drought periods. Scirpus olneyi was established in 12 one-tenth-acre impoundments and subjected to 6 water level and salinity treatments. Drying ponds for 1 and 3 months before the treatments were initiated had no measurable effects on culm density. The 20 ppl salinity treatments reduced culm density, but the 10 ppt salinity treatments and wet and dry controls had little or no effect...