Local Distribution of Hunting Kill 
Information concerning local distribution of 
the hunting kill of Canvasbacks within the Upper 
Chesapeake region was obtained through an 
analysis of the distribution of 370 weighted 
recoveries of birds banded outside Mary- 
land and Virginia (table 115), These recoveries 
were reported during the years 1954-58. The 
number per year ranged from 40 in 1954 to 
97 in 1958. 
The Chester River section is the most im- 
portant harvest area. Approximately 38% of 
the kill occurred in the central eastern shore 
area (Chester River, Eastern Bay, and Chop- 
tank River sections); 21% in the north Chesa- 
peake area (Upper Western Shore, Susquehanna 
Flats, and Upper Eastern Shore sections); 
16% in the Potomac River sections; 12% in the 
Blackwater-Nanticoke and Lower Eastern 
Shore sections; 10% in the Patuxent River and 
Central and Lower Western Shore sections; 
and 3% in the Coastal section. The distribution 
of the kill by habitat was: brackish estuarine 
bays - 53%; fresh and slightly brackish es- 
tuarine bays - 33%; salt estuarine bays - 11%; 
and coastal bay and impoundment complex - 3%, 
Kill data arranged by months showed that 
14% of the kill was in November, 54% in 
December, and 32% in January. 
Harvest Areas of Birds Banded in Upper 
Chesapeake Region 
Data concerning harvest areas of Canvas- 
backs banded in the Chester River, Eastern 
Bay, Choptank River, Hooper Island, Solomons, 
Sandy Point (Anne Arundel Co.), and Gibson 
Island areas during the years 1955-58 came 
from 338 indirect recoveries (table 116), Re- 
coveries included 132 birds banded in winter 
and 206 banded in spring. A little more than 
half of the kill of winter-banded birds and 
about two-thirds of the kill of spring-banded 
birds was in the Mid-Atlantic States. Nearly 
half of the recoveries of winter-banded birds 
and nearly three-fifths of the recoveries of 
spring-banded birds were from Maryland alone, 
Other important harvest areas were in the 
North Central States, with the greatest (local) 
concentrations of kill in Minnesota. Fairly 
large numbers also were taken in the eastern 
Great Lakes area and in the prairie provinces. 
A separate study of the breeding-ground 
derivation of Canvasbacks killed in the mid- 
Atlantic states (chiefly Maryland, Virginia, 
and North Carolina) indicated that about 49% 
were produced in Saskatchewan, 18% in Mani- 
toba, 16% in Alberta, 11% in North Dakota, 
and 6% in miscellaneous areas (Stewart, Geis, 
and Evans, 1958), A fairly comprehensive 
analysis of recovery data of Canvasbacks 
banded in Maryland, including studies of the 
chronology of the migration, sex and age 
ratios, and mortality rates, was reported by 
Longwell and Stotts (1958). 
52 
GREATER SCAUP 
Aythya marila (Linnaeus) 
Numbers of Greater Scaup in the Upper 
Chesapeake region vary greatly from year 
to year. Fairly large numbers ordinarily are 
present during severe winters, when Greater 
Scaup may outnumber Lesser Scaup. During 
moderate or mild winters, Greater Scaup are 
much scarcer and are usually outnumbered 
by Lesser Scaup. The migration periods of the 
two species seem to be similar (see Lesser 
Scaup). 
Because of the difficulty in distinguishing 
Greater Scaup from Lesser Scaup in aerial 
surveys, the counts of the two species were 
combined, and are presented in the account 
of the Lesser Scaup. 
Habitats 
Greater Scaup ordinarily are largely re- 
stricted to brackish and salt estuarine bays 
and to the coastal bays. Occasionally, during 
migration, fairly large numbers also occur 
in fresh and slightly brackish estuarine bays 
for brief periods. In general, Greater Scaup 
seem to prefer the coastal bays, Chesapeake 
Bay proper, and broad expanses of adjoining 
sounds, bays and estuaries; Lesser Scaup 
tend to range farther toward the upper limits 
of the adjoining estuaries. 
Biogeographic Sections 
General observations indicate that the prin- 
cipal areas inhabited by Greater Scaup are 
the Central Western Shore, Chester River, 
Eastern Bay, Choptank River, Lower Eastern 
Shore, and Coastal sections. 
Food Habits 
The gullet and gizzard food contents of 
44 Greater Scaup were examined. Data for 
43 of these are shown in tables 117-119. In 
addition, one bird was collected on Chin- 
coteague Bay during March. 
Various small mollusks, including both uni- 
valve and bivalve types, the leaves, stems, 
rootstalks, and seeds of submerged plants, 
and bait corn, were the principal foods con- 
sumed by Greater Scaup in the Upper Chesa- 
peake region. In the salt estuarine bays (table 
117), various mollusks predominated in the 
diet, the more important species including 
the gastropods Bittium varium, Mitrella lunata, and 
Nassarius trivittatus; eelgrass and bait corn were 
the chief vegetable foods. Mollusks, and par- 
ticularly the little surf clam (Mulinia lateralis), 
the bent mussel (Brachidontes recurvus) and the 
gastropod Bittium varium, also were the 
