estuarine bays of this section were among the 
last areas to freeze in the entire region. 
Fairly large populations also were present 
for short periods in the Choptank River, 
Central Western Shore, Lower Potomac, and 
Upper Potomac sections. 
Food Habits 
The gullet and gizzard food contents of 35 
Ruddy Ducks were examined. Data for 29 of 
these are shown in tables 144-146. Inaddition, 
four were taken on brackish estuarine bay 
marshes of the Blackwater-Nanticoke section 
during fall (September - November); one was 
collected in the estuarine river marsh of the 
Patuxent River during March; and another was 
collected on the coastal bays, near Ocean City, 
during December. 
The seeds, leaves, and stems of various 
submerged plants and certain small mollusks 
and crustaceans were the principal types of 
food. In the fresh estuarine bays (table 144), 
leaves, stems and rootstalks of wildcelery 
were the predominant food; other foods in- 
cluded sago pondweed and the seeds of grass- 
leaf pondweed; wheat (bait); and certain in- 
vertebrates. In the moderately clear, brackish 
estuarine bays of the Chester, Patuxent and 
Potomac Rivers (table 145), various mollusks 
and crustaceans, and particularly the small 
bivalve Macoma phenaz, small soft-shelled clams 
(Mya arenaria), and amphipod crustaceans (Gam- 
maridae) were eaten most commonly; seeds 
of southern naiad, claspingleaf pondweed, and 
other aquatic plants also were taken in fair 
amounts. The predominant foods eaten by the 
Ruddy Ducks collected on the turbid, brackish 
estuarine bays of Fishing Bay and the Nanticoke 
River (table 146) included the bivalve Baltic 
macoma (Macoma balthica), the little surf clam 
(Mulinia lateralis), the gastropod Acteocina canali- 
culate, and the isopod crustacean Chiridotea coeca. 
The four Ruddy Ducks collected in brackish 
estuarine bay marshes of the Blackwater- 
Nanticoke section had fed on seeds of Olney 
three-square and widgeongrass, the bivalve 
Macoma phenaz, minute shelled crustaceans (Os- 
tracoda) and fish eggs. The bird collected in 
the estuarine river marsh along the Patuxent 
River had fed chiefly on seeds of swamp 
smartweed and paspalum. The bird collected 
on the coastal bays near Ocean City had fed 
on undetermined pelecypod mollusks and seeds 
of widgeongrass and common three-square. 
HOODED MERGANSER 
Lophodytes cucullatus (Linnaeus) 
Hooded Mergansers are fairly common 
spring and fall transients in the Upper Chesa- 
peake region; they occur in scattered small 
59 
flocks wherever habitat conditions are appro- 
priate, Small numbers also are present reg- 
ularly during the winter. High local counts of 
Hooded Mergansers were as follows: 200 on 
Fishing Creek, Anne Arundel County, on April 
4, 1956; 100 on Potomac River, off Mount 
Vernon, Va., on February 8, 1920; 80 0n Black- 
water National Wildlife Refuge, Dorchester 
County, on March 21, 1946; 50 inPort Tobacco 
area, Charles County, on November 19, 1950, 
and on December 27, 1941. The fall migration 
usually is during the period from September 
25 - October 5 to December 5-15, with the 
peak between November 1 and November 30, 
The normal spring migration period extends 
from February 15-25 to May 5-15, with the 
peak between March 10 and April 20. 
Habitats 
A fairly large proportion of the Hooded 
Mergansers of the Upper Chesapeake region 
are found in the fresh and brackish estuarine 
bay marshes of the Blackwater-Nanticoke 
section. Scattered flocks also occur regularly 
in river bottomlands and on interior im- 
poundments and fresh estuarine bays through- 
out the region. Occasionally a few birds are 
present in estuarine river marshes, brackish 
estuarine bays, and other waterfowl habitats. 
Food Habits 
The gullet and gizzard food contents of 10 
Hooded Mergansers were examined (table 147), 
Various types of small fish were the pre- 
dominant food, Other foods included mud crabs 
(Xanthidae), crayfish (Cambarus sp.) dragonfly 
nymphs (Libelluloidea) and caddisfly larvae 
(Trichoptera), 
COMMON MERGANSER 
Mergus merganser Linnaeus 
Common Mergansers are common, although 
rather local, spring and fall transients and 
winter residents in the Upper Chesapeake 
region. They usually occur in scattered small 
flocks ‘of from 6 to 20 individuals. They oc- 
casionally may concentrate in much larger 
numbers on certain favored sites. High local 
counts are 1,171 on the Blackwater National 
Wildlife Refuge, Dorchester County, on Decem- 
ber 23, 1951; 438 on Susquehanna Flats on 
December 28, 1951; 400 on Potomac River 
near Accokeek, Prince Georges County, on 
December 29, 1944; 242 on Wicomico River, 
Charles County, on January 2, 1949; 195 0nthe 
Gunpowder River, Baltimore County, on March 
16, 1947; and 75 on interior impoundments on 
Patuxent Wildlife Research Center, Prince 
Georges County, on February 19, 1949. 
