FALL LOCAL MOVEMENTS,  HABITAT  USE,  AND  POPULATION  DYNAMICS  OF
TUNDRA SWANS ON THE UPPER MISSISSIPPI RIVER

Erik M. Thorson and James A. Cooper.
Department of Fisheries and Wildlife, University of Minnesota, St. Paul, MN  55108. 

Tundra Swan (Cygnus columbianus) use of the Upper Mississippi River (Pools 4-9) has 
increased dramatically over the past 10 years.  This reach of the river is a major fall 
stopover site hosting over 20% of the Eastern Population.  The main objectives of 
this study were to examine local movements, habitat use, and population dynamics of 
swans using this area in fall with telemetry and survey data.  A total of 43 adults 
were radio-marked in the fall of 1998 and 1999.  These swans were tracked with 
aircraft and telemetry vehicles.  Locations were used to describe daily and seasonal 
movements, as they relate to open and closed areas and the pools within the study 
area.  Estimated locations will be overlaid on land cover/use, bathymetry, and 
land/water GIS coverages to investigate differences in use and availability.  Weekly 
aerial survey flights were flown to estimate cygnet and total swan numbers through 
the use of ocular estimates and videography.  Survey data will be used to determine 
swan use-days, peak counts, cygnet:adult ratios, and population changes throughout 
the fall.  Preliminary analysis indicates a general movement out of the closed areas at 
night during the duck hunting season.  Radio-marked birds used a number of different 
sites, and many showed a southward movement within the study area throughout the 
fall.  The length of stay for these swans was roughly 30 days, indicating little 
turnover in this stopover site's population.  The cygnet:adult ratio within the study 
area was significantly higher than the ratio for the entire Eastern Population. 

Keywords:  Tundra Swan, Cygnus columbianus, telemetry, aerial surveys, GIS
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