more general observations. The actual popu- 
lations present during spring and fall probably 
were greater than the figures indicate, be- 
cause only tidewater habitats were covered 
during the surveys. 
During the 1958-59 season, most early 
fall migrants were concentrated on the Sus- 
quehanna Flats. In December, most birds 
were distributed over the Chester River, 
Central Western Shore, Central Potomac and 
Blackwater-Nanticoke sections. Most of the 
wintering population was concentrated on the 
Choptank River, with smaller numbers along 
the coast and in the Lower. Western Shore 
section. The majority of the spring migrants 
were distributed over the Upper Eastern Shore, 
Choptank River, Lower Eastern Shore, and 
Lower Potomac sections. 
Food Habits 
The gullet and gizzard food contents of 34 
Ring-necked Ducks were examined. Data for 27 
of these are shown in tables 104-105, In addi- 
tion to these, four birds were taken in the 
estuarine river marshes along the Patuxent 
River in March, two were taken on brackish 
estuarine bays of the Chester River~Eastern 
Bay area in winter (December 10, February 9), 
and one bird was collected in afreshestuarine 
bay marsh in the Blackwater-Nanticoke sec- 
tion on December 30. 
Leaves, stems, and rootstalks of submerged 
plants; and invertebrate animals were the 
principal foods eaten by the Ring-necked 
Ducks collected on fresh estuarine bays (table 
104), Commonest items were various pond- 
weeds and the gastropod mollusk (Orytrema 
virginica). On the interior impoundments (table 
105), the principal animal foods included 
midge larvae (Chironomidae), snout beetles 
(Curculionidae), and dragonfly nymphs (Li- 
belluloidea); various types of seeds also were 
eaten. The four Ring-necks from the Patuxent 
river marshes had fed almost entirely on 
various seeds; dotted smartweed and arrow- 
arum were commonest, then halberdleaf tear- 
thumb, common burreed, spatterdock, and 
corn (bait). The two birds shot in the Chester 
River-Eastern Bay area had fed chiefly on 
leaves, stems, and rootstalks of widgeongrass 
and claspingleaf pondweed; and various bivalve 
mollusks, including Mulinia lateralis, Mya arenarta, 
and Brachidontes recurvus. The Ring-necked Duck 
collected in the Blackwater-Nanticoke section 
had fed entirely on corn (bait), 
Local Distribution of Hunting Kill 
Information concerning local distribution of 
the hunting kill of Ringnecked Ducks within 
the Upper Chesapeake region was obtained 
through an analysis of the distribution of 
26 weighted recoveries of birds banded outside 
50 
Maryland and Virginia (table 106). These 
recoveries were reported from the Upper 
Chesapeake region during the following years: 
1926, 1940, 1943, 1945, 1946, 1947, 1948, 1949, 
1950, 1951, 1952, 1955, 1956 and 1958. The 
number per year ranged from one in 1926, 
1945, 1946, 1947, 1948, 1952, and 1955, to 
four in 1949 and 1950. 
Kill of Ring-necked Ducks differed from that 
of other waterfowl in being mainly in the 
western shore sections (including Susquehanna 
Flats, Potomac, and Patuxent sections), where 
more than two-thirds of the total kill was 
made. The distribution of the kill by habitat 
types was: brackish estuarine bays - 50%; 
fresh and slightly brackish estuarine bays - 
45%; salt estuarine bays - 3%; coastal bays - 
2%, 
Harvest Areas of Birds Banded in the Upper 
Chesapeake Region 
Data concerning harvest areas of Ring- 
necked Ducks banded in the Gibson Island, 
Chester River, and Blackwater River areas 
during the years 1952-57 came from 38 
indirect recoveries, all of birds banded be- 
tween December 23 and March 16 (table 107), 
A little more than three-fifths of the kill was 
in the Mid-Atlantic States. About one-third 
of the kill was in Maryland alone. Other im- 
portant harvest areas were in the eastern 
Great Lakes-St, Lawrence section and in the 
Southeastern States, 
CANVASBACK 
Aythya valisineria (Wilson) 
Migrant and wintering Canvasbacks usually 
are numerous and fairly well distributed over 
the greater part of the Upper Chesapeake 
region, Great local concentrations occasion-~ 
ally are found in a few choice areas, par- 
ticularly during the fall migration peak. Jan- 
uary inventories for 1953-58 show that the 
wintering population ranged from 44,000 in 
1958 to 351,400 in 1954, averaged approxi- 
mately 194,300, This average figure repre- 
sents about 40% of the continental wintering 
population and about 73% of the Atlantic 
population. The fall migration usually is during 
the period from October 15-25 to December 
15-25, with the peak between November 15 
and December 15. The normal spring migra- 
tion period extends from February 25 - March 
5 to May 1-10, with the peak between March 5 
and April 5. 
Habitats 
The optimum habitats for Canvasbacks are 
fresh and brackish estuarine bays that contain 
