flooded areas. During the breeding season, fulvous tree- 

 ducks feed in rice fields, flooded rice stubble, wet pas- 

 tures, small inland marshes, fish ponds, and crayfish 

 ponds (Lynch 1943, McCartney 1963). 



The major food of the fulvous tree-duck is rice, 

 although they feed on various grass and sedge seeds 

 growing in association with rice. When feeding in 

 marshes, the birds also select seeds of grasses and 

 sedges such as wild millet, paspalum, and cyperus. 

 Animal material makes up only a small portion of the 

 bird's diet (Meanley and Meanley 1959, McCartney 

 1963). 



Fulvous tree-ducks usually form a pair bond when 

 one year old and, unlike most ducks, they remain 

 paired for life. Nesting begins in late May and ex- 

 tends to late August. On the Chenier Plain, the 

 species nests ahnost entirely in rice fields. Clutch size 

 averages between 12 and 15 eggs; both parents are 

 thought to incubate the eggs (McCartney 1963). 



5.3.40 MALLARD (Anas platyrhynchos) 



The maUard is widely distributed throughout 

 Texas and Louisiana in various habitats, and is the 

 major waterfowl of the Chenier Plain. The mallard is 

 considered a late migrant and, unlike many other 

 dabbhng ducks, few mallards pass through the Chenier 

 Plain enroute to other areas. Mallards begin arriving in 

 large numbers in mid-November, gradually increase in 

 abundance during eady winter, and reach a peak in 

 mid-January (Smith 1961). 



Winter abundance is influenced largely by the 

 severity of cold weather in the north. The winter of 

 1974-75 was considered mild, and the January 1975 

 mallard population in southwestern Louisiana was only 

 154,000 (Bateman and Linscombe 1975). On the other 

 extreme, the winter of 1976-77 was much colder and 

 the January 1977 maUard population numbered 

 787,000 in southwestern Louisiana (Bateman et al. 

 1977). 



The mallard is an adaptable species that is found in 

 coastal marshes, rice fields, flooded pastures, or flooded 

 bottomland hardwoods. The species will often use one 

 habitat as a feeding area and another as a rest area. 

 Dillon (1957) found that mallards fed in rice fields at 

 night in the Chenier Plain, then flew to marsh areas 8 

 to 16 km (5 to 10 mi) away to rest. 



Mallards typically eat seeds, and select feeding 

 areas where the seeds of wild plants or agricultural 

 crops are abundant and readily available. Mallards 

 prefer to feed in waters less than 50 cm (19.5 in) deep. 

 Resting areas may be deeper, but mallards are secretive 

 and prefer marshes with small ponds of less than 0.5 ha 

 (1.2 a) or flooded areas with abundant plant cover. 

 Although mallards are occasionally found in brackish 

 marshes, greatest concentrations occur in fresh and 

 intermediate marshes. Preferred mallard foods in rice 

 fields of the Chenier Plain are the seeds of rice, pas- 

 palum, and wild millet (Dillon 1957). Food in fresh 

 and intermediate marshes consists largely of grass and 



seeds of millet, panic grass, cyperus, spikerush, and 

 bulrush. Brackish marsh plants used most often are 

 saltgrass, spikerush and buhush (Chamberlain 1959). 



Courtship and pair formation take place during the 

 wintering season among mallards using the Chenier 

 Plain. However, the birds migrate northward for 

 nesting and brood rearing. 



5.3.41 MOTTLED DUCK (/l»as/«/r/g«/a) 



The mottled duck is a year-round resident of the 

 Chenier Plain and breeds and winters there. Large 

 coastal areas may be utilized by this species in and out 

 of the Chenier Plain area (Singleton 1953, Smith 

 1961). 



In a study by Weeks (1969), two male and two fe- 

 male mottled ducks were equipped with radio trans- 

 mitters over a period of 5 to 38 days. Their home ranges 

 were found to be between 42 and 132 ha (105 and 

 327 a). He felt that the home range was an under- 

 estimate because of the short time period involved. 



Although mottled ducks occupy a wide range of 

 habitats in the Chenier Plain, they prefer fresh and 

 slightly brackish marshes. Other favorite habitats are 

 shallow marshes along the margin of saline and brack- 

 ish bays and lagoons, and freshwater ponds and streams 

 in row-crop agricultural areas (Singleton 1953). 



Studies of mottled duck distribution (Singleton 

 1953) indicate that marshes of the Chenier Plain are 

 heavily used during the summer and fall, and rice fields 

 are heavily used during the winter and spring. Observa- 

 tions in the Louisiana portion of the Chenier Plain sug- 

 gest that habitat use varies only slightly during the an- 

 nual cycle. The use of brackish marshes increases 

 somewhat during late summer because they serve as 

 staging areas following the post-nuptial molt (Weeks 

 1969). Rice fields may be used during late summer as 

 the crop matures. Linscombe (1972) reported problems 

 with rice crop depredarion by mottled ducks. 



The food of mottled ducks in the Chenier Plain is 

 diverse. According to Singleton (1953), insects and 

 fishes were the main foods. Important plant foods were 

 wild millet and rice. Stomachs from ducks killed in salt 

 marshes in Aransas County, Texas, contained 90% wid- 

 geongrass. Bent (1923) found that mollusks, crustaceans 

 and insects accounted for 40% of the mottled ducks's 

 diet, while Smith (1973) found only 7% of the gizzard 

 contents to be of animal origin. Some of this difference 

 may be explained by the trend towards greater use of 

 domestic rice during the past 50 years. Bent did not 

 mention rice specifically as a food source, but Smith 

 found that rice was the major component of the gizzard 

 contents. 



Hatchlings feed mainly on insects (Singleton 1953). 

 Suitable feeding areas often include open water with 

 emergent and submergent aquatic vegetation. 



Mottled ducks usually select one of three types of 

 nesting areas (Singleton 1953). One type is a coastal 

 marsh containing dense stands of saltmeadow cordgrass 



243 



