Vol. 24, No. 10 
Page 5 
Because this figure is considerably higher than the winter aerial census 
(MWRL 24(4):3), its accuracy may be questionable. Errors may have been made 
in estimating the number of marked deer or by double counting some animals, 
though every effort was made to count each deer only once. 
This population estimate is somewhat crude and more censuses are needed. 
We will record all known mortalities in and around the Park and will compare 
aerial counts made this winter with future spotlight censuses. 
Cooperative Waterfowl Research - V/-38-R F.C. Bellrose, S.P. Havera, 
G.A. Perkins, H.K. Archer 
The first sign in Illinois of the fall waterfowl migration is the arrival 
of small flocks of blue-winged teal, usually in late July. Bluewings leave their 
breeding grounds in south-central Canada and north-central U.S. and stop briefly 
in Illinois for food and rest. In the first aerial census this fall (conducted 
8 September by Robert Crompton), bluewings numbered 20,500 in the Illinois River 
valley and 10,000 in the Mississippi River valley. However, teal numbers 
declined in the 2 subsequent weekly censuses. In 1978 through 1980, bluewing 
numbers peaked in the first or second week of September; average peaks were 
42,600 and 16,300 birds in the Illinois and Mississippi valleys, respectively. 
High water in the Illinois Valley throughout summer 1931 inundated mudflats and 
prohibited the growth of moist-soil plants which produce seeds for blue-winged 
teal to feed upon. The lack of mudflats and associated food along the Illinois 
River is probably the primary reason for the large decrease in teal numbers 
observed during the recent aerial censuses. Many birds undoubtedly found food 
in flooded agricultural fields of the bottomlands where they were not censused. 
The fall migration of green-winged teal through Illinois is later and more 
protracted than that of blue-winged teal. In 1978-30, greenwing numbers peaked 
in October or early November; peak numbers averaged 17,600 birds in the Illinois 
Valley and 13,300 birds in the Mississippi Valley. On 14 September 1981, green¬ 
wing numbers totaled 6,300 in the Illinois River valley and 5,800 in the 
Mississippi River valley; 1978-80 averages for a similar date were 9,600 and 
4,100 for the Illinois and Mississippi River valleys, respectively. 
Both species of teal have preferred certain bottomland lakes and water areas 
in recent years. In the Illinois Valley, teal concentrate at Goose Pond (near 
Hennepin) and Rice Pond, as well as Pekin, Rice, Spring, Chautauqua, Anderson, 
Jack, Crane, Meredosia, Flat, and Swan lakes. In the Mississippi Valley, teal 
concentrate largely in the Dallas City to Fort Madison segment of the river and 
the Louisa and Batchtown refuges. 
High water during summer 1901 may have been favorable for some avian species, 
such as egrets. An unusually large number of 6,000 egrets was observed in the 
Illinois Valley. On 14 September, 3,600 egrets were seen in the Mississippi 
Valley. The abundance of egrets, however, does little to console waterfowl 
hunters for one of Illinois' poorest teal-hunting seasons. 
