USGS Home
Contact USGS
Search USGS

A study was initiated in 1969 to determine patterns and causes of local movements of diving ducks on the Keokuk Pool (Pool 19) of the Upper Mississippi River and to relate diurnal activity to hunter harvest and food availability. Within a week of arrival, diving ducks on the Keokuk Pool established a diurnal rhythm of movement with a morning flight at dawn from the highly disturbed middle and upper sections to the less disturbed lower section where birds loafed throughout the day. A return flight upstream to choice feeding areas in the middle and upper sections occurred at dusk. Over 60% of the population using the pool participated in this daily movement and human disturbance was the major factor inducing these mass movements. Hunting activity was most intense in the middle and upper sections and the initiation of mass movements to the lower segment was correlated with the opening of the hunting season. Minimal feeding occurred on the pool during the day and birds fed extensively at night in the middle and upper sections of the Pool. Middle and upper sections were more productive in bottom invertebrates than in the lower section. The distribution of diving ducks was generally correlated with the greatest abundance of benthic organisms.