Waterfowl Distribution Relative to Wetland Acidity

We measured the influence of water acidity on the presence of fish and abundance of aquatic invertebrates to better understand how those variables influence the distribution of waterfowl broods on unmanaged freshwater wetlands in southern New Brunswick. Broods of piscivorous waterfowl were most common on wetlands with pH≥5.5; whereas wetland selection by broods of insectivores was unaffected by acidity. Wetlands with the most invertebrates and most broods and ducklings of insectivores contained no fish. Abundance of aquatic invertebrates was most important in influencing use of wetlands by insectivorous wartefowl, especially American black duck (Anas rubripes). Biomass (dried mass) and diversity of aquatic invertebrates were greater (P<0.005) on wetlands where black duck broods 1-36 days old were observed than on wetlands where broods of those ages were not seen