burreed, wildrice, Walter millet, common 
three-square, softstem bulrush, river bulrush, 
and halberdleaf tearthumb. Arrow-arum 
(seeds) was the all-important Wood Duck food 
and giant burreed (seeds) and halberdleaf 
tearthumb (seeds) were taken in fairly large 
quantities. 
WOODED BOTTOMLANDS 
Wooded bottomlands border the various 
streams of the coastal plain interior. The 
bottomlands along the Patuxent River were 
selected for study as a sample of the habitat. 
The area within the Patuxent Wildlife Re- 
search Center (between Bowie and Laurel, 
Maryland), was studied most intensively. Other 
observations were made along the Patuxent 
River from the fall line (natural boundary 
between Piedmont and Coastal Plain) down the 
river valley for approximately 23 miles, 
nearly to the upper limits of tidewater. A 
few general surveys were made along other 
streams within the Upper Chesapeake region, 
Vegetation 
The vegetation of the wooded bottomlands 
on the Patuxent Wildlife Research Center was 
described in detail by Hotchkiss and Stewart 
(1947), so only the aquatic plants will be 
discussed here. 
Aquatic plants that are fairly common in 
scattered patches in the river proper include 
ribbonleaf pondweed, riverweed, Nuttall water- 
weed, nitella, and filamentous green algae. 
Only shade-tolerant plants grow commonly 
in the shallow runs on the flood plain. These 
include a species of aquatic moss (Fontinalis 
sp.), quillwort, common burreed, ribbonleaf 
pondweed, broadleaf arrowhead, waterplantain, 
eastern mannagrass, goldenclub, swamp 
smartweed, spatterdock, Pennsylvania bitter- 
cress, water-starwort, and mermaidweed, 
Vertebrates Other Than Waterfowl 
Certain species of fish are fairly common 
in the river: the red-sided dace (Chnostomus 
vandoisulus), fallfish (Semotilus corporalis), com- 
mon shiner (Notropis comutus), Johnny darter 
(Etheostoma nigrum), and yellowbelly sunfish 
(Lepomis auritus). Eastern redhorse suckers 
\(Moxostoma macrolepidotum) migrate upstream in 
good-sized schools in late winter and early 
spring. Other species of fish characteristic 
of more sluggish waters live in the deeper 
pools in the runs back on the flood plain. 
These include the American eel (Anguilla rostrata), 
pirate-perch (Aphredoderus sayanus),.redfin picke- 
rel (Esoz americanus), chain pickerel (Esoz niger), 
pumpkinseed sunfish (Lepomis gibbosus), golden 
Shiner (Notemigonus crysoleucas), and. mud minnow 
20 
(Umbra pygmaea). Frogs and salamanders con- 
gregate in bottomland pools to breed. Several 
species of reptiles live in the wooded bottom~ 
lands, including the snapping turtle (Chelydra 
serpentina), which occasionally preys on water- 
fowl. The more important mammalian preda- 
tors that travel along the margins of the water 
courses are: the raccoon (Procyon lotor), mink 
(Mustela vison), and gray fox (Urocyon cinereoargen- 
teus). The common raptorial birds are the Red- 
shouldered Hawk and the Barred Owl. 
Invertebrates 
Many species of aquatic invertebrates in- 
habit the Patuxent River and the smaller runs 
of the flood plain. Pelycepod mollusks that are 
common include the river clam (Elliptic com- 
planatus) and two much smaller species, Pisidium 
atlanticum and Sphaerium sp. Small gastropod 
mollusks that occur regularly are: Amblozis 
decisum, Gyraulus sp., and Physa sp. Crayfish 
(Cambarus sp.) are fairly numerous. The lar- 
vae and adults of numerous species of aquatic 
insects are present. Principal insect groups 
include: Odonata (dragonflies and damselflies), 
Gerridae (water striders), Corixidae (water 
boatmen), Trichoptera (caddisflies), Dytiscidae 
(predaceous diving beetles), Gyrinidae (whirli- 
gig beetles), Curculionidae (snout beetles), 
Culicidae (mosquitoes), and Chironomidae 
(midges), 
Waterfowl 
The principal transient waterfowl include 
Wood Ducks (approximately 40% of the total), 
Mallards (30%), Black Ducks (20%), and Hooded 
Mergansers (5%). Waterfowl that make up the 
remaining 5% are: Pintails, Green-winged 
Teal, Blue-winged Teal, American Widgeons, 
Ring-necked Ducks, Common Goldeneyes, Buf- 
fleheads and Common Mergansers. 
In general, greater numbers of waterfowl 
frequent the wider sections of the river than 
the narrow branches or the flood-plain runs, 
Hooded Mergansers differ from other species 
in that they are restricted to the river, and 
seem to show little preference between wide 
portions and the more narrow branches, 
Numbers of transient waterfowl vary greatly 
from year to year. Numbers of migrating Mal- 
lards, Black Ducks and Wood Ducks seem to 
be correlated with the abundance of the local 
mast crop, particularly beechnuts and the 
acorns of pin oak and white oak. In years of 
low mast production, there seldom are more 
than 20 birds per square mile of flood-plain 
forest. During years with bumper mast crops, 
there may be 50 to 100 birds per square mile 
of habitat. Flock size also generally is larger 
during years when mast is abundant; many 
flocks will have 10 to 25 birds. Large numbers 
of ducks take refuge in the bottomlands during 
