Habitats 
Most transient and wintering Gadwalls occur 
in the slightly brackish estuarine bays of the 
Central Potomac section. The more common 
submerged plants in this area are widgeon- 
grass, claspingleaf pondweed, and the intro- 
duced Eurasian watermilfoil. Gadwalls in the 
Blackwater-Nanticoke, Lower Eastern Shore, 
and Coastal sections, usually frequent the 
natural "'stillwater'' ponds and impoundments 
of the larger marshes. Widgeongrass and 
muskgrass ordinarily are the most numerous 
submerged plants in these marshes, although 
sago pondweed and claspingleaf pondweed are 
common locally. 
Gadwalls breed locally in brackish and 
salt estuarine bay marshes of the Blackwater- 
Nanticoke and Lower Eastern Shore sections. 
We found four nests in this area. One was 
located at the edge of a thicket along a road- 
side ditch; one was in an unburned patch of 
saltmeadow cordgrass ina burnedover marsh- 
meadow; one was in abrushy margin of marsh- 
meadow composed of saltmeadow cordgrass; 
and one was on a marsh island in the Manokin 
River, where the vegetation was chiefly salt- 
meadow cordgrass and scattered hightide- 
bush, 
Biogeographic Sections 
The average distribution of Gadwalls during 
the January inventories of 1955-58 was: Central 
Potomac section, 73%; Lower Potomac section, 
11%; Chester River section, 9%; Blackwater- 
Nanticoke section, 7%; Upper Potomac section, 
+%; other sections 0. These figures show the 
importance of the central Potomac estuary. 
Seasonal changes in numbers during 1958- 
59 are shown in table 66. The Central Potomac 
section was the outstanding Gadwall area in 
the region. On at least one survey, fair num- 
bers of Gadwalls also were recorded in the 
Coastal, Lower Eastern Shore, and Lower 
Potomac sections. 
Food Habits 
The gullet and gizzard food contents of 29 
Gadwalls were examined. Data for 24 of these 
are shown in table 67. Five other birds were 
collected on fresh estuarine waters of the 
Upper Potomac section during November 
and December. 
The leaves, stems, and rootstalks of sub- 
merged plants were the predominent foods 
in both series. Widgeongrass was the principal 
food taken by the birds from the brackish 
estuarine bay marshes; eelgrass, muskgrass, 
and claspingleaf pondweed also were consumed 
in fair amounts. Various seeds, saltgrass 
rootstalks, and fish were taken in small 
amounts. Southern naiad was the commonest 
40 
food of the Gadwalls from fresh estuarine 
waters of the Upper Potomac section; small 
amounts of grassleaf pondweed and red algae 
also were taken. 
PINT AIL 
Anas acuta Linnaeus 
Pintails are fairly common local winter 
residents and spring and fall transients, par- 
ticularly in the areas along the eastern shore 
of Chesapeake Bay. There are smaller popula- 
tions in a few scattered locations elsewhere 
in the region. January inventories for 1953-58 
show that the wintering population ranged from 
13,900 in 1958 to 66,700 in 1953, averaged 
approximately 49,600. This average figure 
represents about 1% of the continental popula- 
tion and 15% of the Atlantic population. The 
fall migration usually is during the period of 
August 25 - September 5 to December 10-20, 
with the peak between October 25 and December 
5. The normal spring migration extends from 
January 15-25 to April 25 - May 5, with the 
peak between February 15 and March 20. 
Habitats 
The optimum combination of habitats for 
Pintails in the Upper Chesapeake region ap- 
pears to be the shallow, fresh or brackish 
estuarine waters and the adjacent agricultural 
areas with their scattered impoundments. 
These conditions are widespread along the 
eastern shore in the area extending from the 
Bohemia River to the Choptank River. Surveys 
of wintering populations during 1955-58 showed 
that, on the average, 50% of the Pintails of the 
Upper Chesapeake region occurred in this 
area. Periodic surveys during the 1958-59 
season indicated that from 44% to 90% of the 
total population was found here. The greatest 
concentrations were in the complex of brack- 
ish estuaries and agricultural fields of the 
Chester River section. 
Large numbers of Pintails also occur 
locally in the extensive estuarine bay marshes 
and adjoining estuarine river marshes of the 
Blackwater-Nanticoke and Lower Eastern 
Shore sections. The 1955-58 winter surveys 
showed that an average of 47% of the Upper 
Chesapeake population was in these areas 
(24% in the fresh and brackish estuarine bay 
marshes of the Blackwater-Nanticoke section 
and 23% in the salt estuarine bay marshes 
of the Lower Eastern Shore section). The 
periodic surveys in 1958-59 indicated that from 
12% to 27% of the Pintails were in these areas | 
during the period from October to January. 
Numbers were much lower during Marchafter 
the onset of spring migration. 
Pintails also frequent marshes of other 
sections. During the fall and spring, local 
