severe stormy weather. At these times, many 
flocks will have from 50 to 100 ducks. 
The gullet and gizzard food contents of 101 
transient waterfowl collected in wooded bot- 
tomlands along the Patuxent River were ex- 
amined. Beechnuts and the acorns of pin oak 
and white oak are the preferred foods of Wood 
Ducks, Mallards, and Black Ducks. Other 
fruits and seeds that are important, par- 
ticularly during years of low mast production, 
include hornbeam, poison-ivy, grape, black- 
gum, sweetgum, halberdleaf tearthumb, and 
dotted smartweed. Fairly large quantities of 
leaves and stems of ribbonleaf pondweed and 
Nuttall waterweed occasionally are eaten, 
Small mollusks are a supplementary food for 
Black Ducks, and, to a lesser extent, for 
Mallards. Fish and crayfish (Cambarus sp.) ap- 
parently are the principal foods of Hooded 
Mergansers in this habitat. 
Wintering waterfowl usually are scarce in 
the wooded bottomlands. Breeding populations 
usually are composed of a few scattered pairs 
of Wood Ducks. 
INTERIOR IMPOUNDMENTS 
Artificial impoundments are _ scattered 
throughout the coastal plain interior of the 
Upper Chesapeake region. These were made 
by constructing dams or dikes to impound 
streams or the run-off waters of small water- 
sheds. Most of these ponds are rather small, 
usually from 1 to 30 acres. A few larger 
ones may cover as much as 100 acres, Most 
of the ponds are managed for fishing or are 
used as watering ponds for livestock. A few 
are managed specifically for waterfowl, These 
include several at the Patuxent Wildlife Re- 
search Center. Construction and management 
procedures are described by Uhler (1956), Ar- 
tificial impoundments in New Jersey were 
studied by McLain (1957), 
Vegetation 
The vegetation of interior impoundments 
usually includes a large number of species. 
The species can be grouped according to three 
major zones: open-water, shore-line and 
drawdown. Table 14 shows many of the charac- 
teristic plants of each of these zones as they 
occur in the impoundments at the Patuxent 
Wildlife Research Center. Waters of most 
artificial ponds are acid, sometimes strongly 
acid, and contain no choice submerged food 
plants. Plant foods of open-water and shore- 
line zones are used by waterfowl, but they 
are not first-rate waterfowl foods. The draw- 
down zone, which is produced by summer 
drainage to expose mud flats, results in the 
growth of a large number of important water- 
fowl food plants. Reflooding in October when 
thei seeds have matured makes food available 
21 
for waterfowl. Certain pest plants, including 
common beggartick and pilewort, are held in 
better check by a biennial drawdown. 
Vertebrates Other Than Waterfowl 
Numbers and kinds of vertebrates using 
artificial impoundments vary greatly because 
of variations in relative fertility of the waters, 
depth and size of the ponds, and the type of 
pond management. The more characteristic 
fish, including several species that often are 
stocked, are: the chain pickerel (Fsozr niger), 
largemouth black bass (Micropterus salmoides),' 
Pumpkinseed sunfish (Lepomis gibbosus), bluegill 
sunfish (Lepomis macrochirus), black crappie 
(Pomoxis nigromaculatus), golden shiner Notemigonus 
crysoleucas), and mud minnow (Umbra pygmaea). 
Invertebrates 
A great variety of invertebrates, particularly 
aquatic insects, occur insomeartificial ponds. 
The more numerous and widespread types are; 
Isopod Crustaceans (Asellus sp.) 
Amphipod Crustaceans (Gammaridae) 
Watermites (Hydrachnellae) 
Mayfly Nymphs (Ephemeroptera) 
Damselfly Nymphs (Zygoptera) 
Dragonfly Nymphs (Anisoptera) 
Water Striders (Gerridae) 
Water Scorpions (Nepidae) 
Giant Water Bugs (Belostomatidae) 
Back Swimmers (Notonectidae} 
Water Boatmen (Corixidae) 
Alderfly larvae (Sialidae) 
Caddisfly larvae (Trichoptera) 
Predaceous Diving Beetles (Dytiscidae) 
Whirligig Beetles (Gyrinidae) 
Water Scavenger Beetles (Hydrophilidae) 
Snout Beetles (Curculionidae) 
Mosquito larvae (Culicidae) 
Midge larvae (Chironomidae} 
Horsefly larvae (Tabanidae) 
Waterfowl 
The characteristic species of transient wa- 
terfowl of interior impoundments are: 
Primary Species 
Pintail (local) 
Ring-necked Duck 
Canada Goose 
Mallard 
Black Duck 
Secondary Species 
Green-winged Teal Common Goldeneye 
Blue-winged Teal Bufflehead 
American Widgeon Ruddy Duck 
Wood Duck Hooded Merganser 
Redhead Common Merganser 
Lesser Scaup American Coot 
