Illinois Natural History Survey - University of Illinois

Waterfowl Aerial Inventories


Aerial InventoryIn the fall of 1938 and in subsequent years, Dr. Frank C. Bellrose traveled by car and boat with binoculars and a spotting scope to record waterfowl abundance from various vantage points in the Illinois River valley. When Bellrose initiated experimental aerial inventories in the fall of 1946, he noted that the time required to inventory the Illinois Valley was reduced from a week to a day and that a large part of the Mississippi Valley could be included in the one-day flight. Since 1948, waterfowl aerial inventories have been conducted by the INHS.

Approximately 214 miles of the Illinois River, from Spring Valley to Grafton, and 272 miles of the central Mississippi River, from Alton to Moline, are aerially inventoried for waterfowl weekly from September through early January.

The purpose of these aerial inventories is not to acquire complete counts of waterfowl numbers within specific geographic areas but to estimate the number of each species in order to provide an index of temporal changes within and among years and to document the distribution of the species throughout the monitored regions. Because of the efforts of the INHS with the long-term support of the Illinois Department of Natural Resources, the annual inventory data on numbers and distribution of migratory waterfowl in Illinois is unequaled.

We aerially inventory 23 locations on the Illinois River and 18 locations on the central Mississippi River weekly. Flights are generally scheduled for each Monday beginning in early September and once a flight is completed, results are posted as soon as possible.

Click here to view a map of locations.

INHS Aerial Inventory Observers

Dr. Frank C. BellroseRobert Chuck Holzwarth and Michelle HorathAaron Yetter

Frank Bellrose                Robert "Tud" Crompton               Michelle Horath                          Aaron Yetter




Illinois River
Central Mississippi River
09/21/2015   09/21/2015
09/16/2015 09/16/2015  weathered out
09/09/2015 09/09/2015 09/09/2015
08/31/2015 08/31/2015
12/29/2014   12/29/2014
12/17/2014   12/17/2014
12/09/2014  12/09/2014 12/09/2014
12/03/2014  12/03/2014 12/03/2014
11/25/2014  11/25/2014 11/25/2014
11/20/2014  11/20/2014 11/20/2014
11/12/2014 11/12/2014 11/12/2014
11/05/2014 11/05/2104 11/05/2014
10/29/2014  10/29/2014 10/29/2014
10/20/2014  10/20/2014 10/20/2014
10/16/2014  10/16/2014 10/16/2014
09/23/2014   09/23/2014
09/16/2014  09/16/2014 09/16/2014
09/11/2014 09/11/2014 09/11/2014
09/03/2014 09/03/2014 09/03/2014
01/08/2014   01/08/2014
12/30/2013   12/30/2013
weathered out
weathered out
weathered out


Click here to view Aerial Inventory Data archived by IDNR
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Illinois Natural History Survey

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