SIZE AND COMPOSITION OF THE POPULATION 
Annual changes 
The approximate numbers of waterfowl win- 
tering in the Upper Chesapeake region are 
shown in table 1. The Upper Chesapeake popu- 
lation averaged about 4% of the entire con- 
tinental population and about 23% of the Atlantic 
population. Waterfowl gradually increased in 
the Upper Chesapeake region from 1953 to 
1955, then decreased drastically from 1956 to 
1958. This reduction probably was the result 
of increased hunting pressure along the mi- 
gration routes and on the wintering areas, 
plus drouth in an increasingly greater part 
of the breeding grounds of the 'prairie- 
provinces" of Canada. 
Numbers of waterfowl in each of the groups 
varied considerably from year to year, but 
numbers of diving ducks and dabbling ducks 
varied most and influenced the overall totals 
most strongly. The numbers of geese varied 
least, indicating that the goose populations 
were more stable than the other waterfowl 
populations. Diving ducks reached maximum 
numbers in 1954, but all other groups, and the 
waterfowl population as a whole, reached 
greatest numbers in 1955. Waterfowl of all 
groups were at their lowest point in 1958, 
except for the sea ducks and mergansers, 
which were scarcer in 1956 and 1957, Since 
Upper Chesapeake waterfowl breed in many 
different areas, it is not surprising that 
changes in the numbers of different kinds of 
waterfowl are not always parallel. 
Despite the general trends in numbers from 
year to year, there was enough variation that 
the different species and groups of species 
made up somewhat different proportions of the 
total population each winter. The Mallard, 
scaup, and Ruddy Duck varied more than the 
other species. Species composition of the 
wintering population in the different years is 
shown in table 2. 
In the average for all years, diving ducks 
were most numerous, making up 42% of the 
population. Others, in order, were dabbling 
ducks (29%), geese (18%), swans (4%), coots 
(3%), sea ducks (Oldsquaws and scoters) and 
mergansers (2%), and unidentified ducks (2%). 
Considered by species, the Canvasback, Canada 
Goose, Black Duck, and scaup made up more 
than half the average winter population. Other 
important species included the Whistling Swan, 
Mallard, Pintail, American Widgeon, Redhead, 
and Ruddy Duck. 
Seasonal Changes 
Seasonal changes in numbers of waterfowl 
are shown in table 3. The combined numbers of 
all species increase rather abruptly during late 
October and November and reach a peak in 
early December as large populations of both 
transient and wintering waterfowl concentrate 
in the Upper Chesapeake region. Numbers 
decline gradually during the winter as tran- 
sient populations continue to move southward, 
Numbers continue to decline in early spring 
(March) as departures of wintering birds 
outweigh arrivals of spring transients from 
the south. Numbers decline more conspicu- 
ously in April when most of the remaining 
transient and wintering birds leave for the 
breeding grounds to the far north and north- 
west, Only the local breeding birds remain 
during late spring and summer. Numbers 
increase again when fall migration begins 
in September. 
Pronounced seasonal changes in populations 
of each major group of waterfowl also occur 
throughout the year (table 3), The populations 
of dabbling ducks and geese steadily build up 
during the fall, reaching a peak in late Novem- 
ber and early December followed by a moderate 
decline in winter and a gradual movement out 
of the region in early spring (March and early 
April), Comparatively small breeding popula- 
tions of dabbling ducks (chiefly Black Ducks) 
remain in the region during late spring and 
summer. Diving ducks arrive in large numbers 
in late fall (November and early December), 
reach their peak in winter, maintain their 
numbers fairly well in early spring (March) 
and then depart rather abruptly for the breeding 
grounds during April. Minor groups such as 
swans and coots reach their population peak 
in late fall, whereas sea ducks and mergansers 
ordinarily are most numerous in winter. The 
greatest concentrations of all major waterfowl 
groups occur during the late fall, winter, and 
early spring (November-March). Seasonal 
changes in populations of each species of 
waterfowl are described in detail inthe species 
accounts. 
Because of the population changes in various 
groups of waterfowl, the composition of the 
total waterfowl population varies considerably 
from one season to another. Major changes 
in composition that took place during the 1958- 
59 season (table 4) may be summarized as 
follows: 
October 2-10.--Dabbling ducks were most 
numerous (87%), with American Widgeons 
alone making up 58% of the population. 
Black Ducks (18%) also were fairly nu- 
merous. Canada Geese were present in 
fair numbers (11%), but diving ducks 
were almost entirely lacking. 
November 3-12.--Dabbling ducks (41%) were 
the predominant group, but diving ducks 
(27%) and geese (27%) also were important 
components of the total population. Canada 
Geese alone made up over one-fourth of 
the total population. American Widgeons, 
Ruddy Ducks, Black Ducks, and Canvas- 
backs constituted over one-half of the total. 
