Table 63 
FOODS OF 17 BLACK DUCKS FROM PATUXENT RIVER BOTTOMLANDS+ 
Seeds 65% (38-86) 
Hornbeam . hi% (18-68) 
Poison-ivy 18% ( 3-4) 
Blackgum 12% ( 1-37) 
Grape 12% ( 1-37) 
Dotted Smartweed 12% ( 1-37) 
Common Burreed 6% ( +~29) 
Waterpepper 6% ( +-29) 
Rice Cutgrass 6% ( +-29) 
Sweetgum 6% ( +-29) 
Black Cherry 6% ( +29) 
Mast 53% (27-78) 
“a, Beech 35% (1h-62) 
Oak 2% ( 6-50) 
Roptstalks of Common Burreed _6% ( +-=29) 
Undetermined Herbaceous Leaf Fragments _6% ( +29) 
Animal Food 53% (27-78) 
Ambloxis decisum (Gastropoda) 41% (18-68) 
Sphaerium sp. (Pelecypoda) 12% ( 1-37) 
Physa sp. (Gastropoda) 6% ( +-29) 
Gyraulus sp. (Gastropoda) 6% ( +-29) 

1 Collected during fall winter and early spring. Percentage occurrence of 
foods that made up 5% or more of the volume in individual birds. Figures in 
parentheses show 95% confidence limits. 
129 
