Relationships between Waterfowl and Macroinvertebrate Densities in a Northern Prairie Marsh

This study examined the relationships of waterfowl and American coot (Fulica americana) densities with macroinvertebrate levels in several diked ponds (cells) within the Delta Marsh, Manitoba. Following a year of normal water levels in 1980, the experimental cells were pumped to a depth of 1 m above normal for a period of 2 years (1981-82). Simple correlations between waterfowl and macroinvertebrate densities, coupled with behavioral observations, suggest that invertebrate densities may affect breeding waterfowl densities during springs with normal water depths. There were no significant correlations (P > 0.05) between waterfowl and macroinvertebrate densities during springs with above-normal water levels or during any of the fall periods. Coots showed no significant correlations (P > 0.05) with macroinvertebrate levels during any of the periods examined. This study suggests that future research on habitat selection by breeding waterfowl must address macroinvertebrates and/or factors affecting invertebrate distribution and abundance.