in one, and molluscs In five. Harmon (1962) studied the food habits of Lesser 

 Scaup wintering off the Louisiana coast. He examined the gullets and gizzards 

 of 32 scaup collected from 100 yards (91 m) to 4 mi (6.4 km) south of Rockefel- 

 ler Refuge, and found that 99.8% of the food was surf clams ( Mulinia lateralis ). 



Rogers and Korschgen (1966) conducted an extensive study of the food habits 

 and reported the stomach contents of 37 Lesser Scaup. Twenty of these were col- 

 lected in December 1959 in marshes around Lake Borgne , near New Orleans; the 

 rest were taken from roadside ditches and ponds near Grand Chenier in late Feb- 

 ruary and early March 1960. These birds had subsisted largely on fish (41.8% 

 by volume) and crustaceans (16.6%); the only fish identified in the remains was 

 sheepshead minnow ( Cyprinodon variegatus ). The crustacean foods identified were 

 crayfish (Carabarinae - 7.0%), freshwater shrimp ( Palaemonetes sp. - 4.5%), side- 

 swimmers ( Hyalella sp. - 3.1%), and opossum shrimp (Mysidae - 1.3%). Small 

 amounts of insects (4.0%) and snails (1.0%) were also eaten. Vegetable matter 

 made up 37.3% of the diet. Identified plant foods were sawgrass ( Cladium jamai- 

 cense - 6.9%), bulrush ( Scirpus spp. - 3.8%), and widgeongrass (1.9%); the rest 

 of the food consisted of small spiral shells ( Nassarius acutus ). 



Texas Twenty wintering Lesser Scaup collected on the Laguna Madre 

 had eaten 22.1% plant food, all of which was shoalgrass - Diplanthera wrightii 

 (McMahan 1970). Of the rest, 39.1% was unidentified organic matter. Snails 

 (12.2%), clams (15.2%), and decapod crabs (10.8%) formed the bulk of the animal 

 foods, but fish fragments (0.2%) and shrimp (0.4%) had also been ingested. One 

 clam ( Anomalocardia cuneimeris = A. auberiana ) was eaten more than any other 

 animal (Emerson and Jacobson 1976). 



IMPORTANT BIOLOGICAL PARAMETERS 



Egg Laying The Lesser Scaup is a late-nesting duck. Nesting may begin 

 in some areas in mid-May, but the peak of nesting is generally in early June. 

 Some nests may not be started until July (studies summarized by Bellrose 1976). 



Mean Clutch Size The average clutch in 880 nests observed in studies in 

 10 breeding areas was 9.0 eggs (Bellrose 1976). Palmer (1976b) reported that 

 the clutch size was usually 9-11 eggs, and noted one study (Keith 1961) in 

 which mean clutch size declined during the laying period (from 10.6 for eggs 

 laid before 16 June to 8.5 for those laid after 30 June). 



Lesser Scaup sometimes lay eggs in the nests of other scaup or other spe- 

 cies of ducks (Palmer 1976b); one "dump nest" contained 26 eggs (Phillips 1925 

 in Palmer 1976b). This trait makes calculation of true clutch size difficult, 

 and several authors have assumed that all clutches containing more than 14 eggs 

 are the result of the efforts of more than one female. 



Incubation Period Palmer (1976b) reported the incubation period as 21-22 

 days and cited one study (Vermeer 1968) that gave a range of 21-27 days. Bell- 

 rose (1976) reported that the average incubation period was 25 days. 



Hatching Success In a series of studies involving more than 1,000 nests, 

 about 43% were successful (Bellrose 1976). The average number of hatched young 



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