Appendix 6.3(11) Continued 



duction; this region is commonly referred to as the "pothole country". This 

 region contains glacially-derived potholes, ponds and marsh regions with 

 abundant food supplies and protected habitat. Mallards outnumber other spe- 

 cies indigenous to the region (Hawkins 1964) . The Lower Mississippi River 

 Valley and the coastal marshes and prairies of Louisiana constitute primary 

 wintering grounds (Hawkins 1964). Mallards are present in large numbers in 

 the Chenier Plain from late September until March. 



The mallard is a dabbler, whose diet consists almost exclusively of 

 plant materials. Glasgow and Junca (1962) found 98% plant material in 226 

 mallard crops. However, the diversity of types and parts of plants utilized 

 shows great adaptability by the species to prevailing food supplies. Mal- 

 lards were among the first ducks to make use of domestic rice as a diet 

 staple. Like geese, they browse roots of marsh plants, and are well suited 

 to dabble for aquatic species, such as widgeongrass. Mallards appear to 

 prefer freshwater marsh vegetation and spend most of the winter in fresh 

 marshes adjacent to rice fields (Louisiana Wildlife and Fisheries Commission 

 1961). 



Mallards generally constitute around 20% of the total duck harvest in 

 Louisiana. For the parishes and counties of Calcasieu, Cameron, Vermilion, 

 Chambers, Jefferson and Orange, the figure is slightly lower (14.8%) be- 

 cause of the great diversity of duck species available to hunters in the 

 Chenier Plain. The point system has also reduced the harvest of mallards. 

 A high point value has been placed on mallards, because of a decline in over- 

 wintering numbers related to adverse conditions in their breeding grounds 

 (Louisiana Wildlife and Fisheries Commission 1961) . 



Mottled duck (Anas fulvigula) 



This mallard-like duck is the only year-long resident dabbler on the 

 western Gulf coast and the only abundant breeder in the Chenier Plain 

 marshes. Like the mallard, it is a favored game bird, although its contri- 

 bution to the harvest numbers is proportionately less. 



Mottled ducks are generally nonmigratory, and numbers remain constant 

 throughout the year, with the exception of a small percentage that irregu- 

 larly migrates to Texas and Mexico (Lowery 1974a) . This movement occurs in 

 response to periodic adverse climatic conditions. The northern limit of the 

 mottled duck's range is normally no farther than the coastal rice prairies 

 of the Chenier Plain (Lowery 1974a). Average peak population in the Chenier 

 Plain in spring and summer months numbers about 50,000 birds. 



Food habit studies have produced varying estimates of the relative 

 amounts of plant and animal materials eaten by mottled ducks. In an early 

 study, Bent (1923) found that mollusks, crustaceans and insects accounted 

 for 40% of the diet, while Smith (1973) found only 7.0% of their gizzard 

 contents to be of animal origin. Some of this difference may be explained 

 by the consumption of domestic rice by mottled ducks during the past 50 

 years . 



Nesting takes place in intermediate and brackish marshes, near open 

 water bodies, and in grass stands, where the nest is hidden from view of 



91 



